I have a question.
What was there first when designing hookless wheels.
The design and they, the manufacturers, found that the limit a tire stayed on safely was 5 bar max.
Or was the limit 5 bar rule already there and the design based on this existing rule of 5 bar?

I mean, is it technically not possible to create a hookless wheel that can hold a tire on at, lets say, 6 bar?
Why was it set on 5 bar at some point? Was this the result of testing after the design was finished and they found it couldn’t hold a tire safely beyond that pressure.
And started calculating optimal pressure to weight with that as a starting point?

Jeroen

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Owner at TRIPRO, The Netherlands

I'm guessing the process was "we can manufacture wheels quicker and cheaper by eliminating the hook". And then they probably determined 5 bar was the safe max PSI. Zipp and Enve seem all in on hookless, and it does seem like the "technology" is safer at lower pressure's, which wider tires will allow.

There are some ways you could increase the pressure but they all have trade offs, mostly about mounting the tire. A tire bead with less stretch would be one way to do that. You could also increase the actual diameter or the wheel, specifically the edge of the rim, or decrease the diameter of the bead. A potential way around this is to increase the diameter of the rim and increase the depth of the rim channel, which would give more slack for mounting. You can only go so far with this until the rim edge/tire interface is happening up the sidewall at a section of rubber not designed for that.

There's also the added complication that the tire and rim manufacturers are usually different, so the margin for error needs to be greater. In theory if Zipp made hookless rims only for specific Zipp (or similarly known QC controlled) tires then the error margin could be lessened.

My guess is that a limitation of design was the ability to mount by hand, or at least with common plastic tire levers. That will fundamentally limit the psi unless there is something positively engaging the tire to provide extra holding force. Aka a hooked rim.

I've been avoiding tubeless (and disk brakes) because I just didn't didn't want the hassles. I was quite content with my HED wheels and 25mm tires with latex. But that all changed when I rode a bike with ENVE's latest 3.4 wheels and 28mm tubeless tires at 60 PSI. No loss of speed and a limo-like ride.

I bought a new road bike almost on the spot because of how good the system felt.

My triathlon bike is a Felt IA with rim brakes and latex tubes. To make a meaningful upgrade, I would have to jump to a modern TT bike with disc brakes. I am not there yet, but I cannot deny the dramatically superior ride I would get with 28mm tubeless on the latest carbon wheels.

1. One thing is what the industry offers to buy and the other thing is what people ride nowadays. There’ll always be a lag of a couple of years, simply due to limited riders’ budgets (there’re other reasons like buyers’ hesitation / negative sentiment, that you seem to exaggerate). If only any new beautiful disc wasn’t costing us over 2’000 USD…

2. Preferred wheel and tire choice for road cycling isn’t the same as for triathlon nor TT. Triathlons & TTs are faster, often non-drafting and usually on better closed roads chosen specifically for a race. This makes the aerodynamic properties more important than rolling resistance, even more than in the same comparison for road cycling. Your preferred tire width for road bike might be 28/28 or 30/30 nowadays, but it’s probably 25/28 for a triathlon bike. Most triathlons are on the roads, so I don’t think 25mm is entirely dead, as it’s the most aerodynamic choice for 19-21 inner width wheel.

3. Would you care to share some bike count data from the last Kona and/or Nice? Or at least the pro bikes, please. We would clearly see how few of those pro riders rode anything more than 25mm in the front.

I am no Marcag, but I think most of us already agree that 28mm is the sweet spot for the rear tire - my issue is the front wheel on a Tri, or even more specifically, a TT bike.

For example, the GCN video comparing tire width vs speed that concluded there is statistically no difference, but they had a max speed of 23.6mph - pretty slow even by my 77 year old standards. "https://www.youtube.com/watch?v=AK5KLvrzrb4"

Again, I remain unconvinced for the front wheel.

"Road" is a wide range of terrain. Consider IM New Zealand's rough chipseal, versus some other courses with smooth asphalt. There are plenty of courses where I'd happily go with the wider / lower pressure tires.

Yeah, I resisted for a long time. Until I tried 30mm tires on my road bike in my mountain-y terrain. The difference is not subtle.

It's a problem for me. I used to spend around 50% of my time on my TT bike - which benefited me immensely when racing other roadies in TT. I could beat people with superior physiology simply by being trained for the TT position.

Now when I walk into my garage for a "TT bike day" I often cringe inwardly looking at the 23mm tires, and then grab my road bike instead.

I make up the difference by spending 100% of my Zwift time in the TT extensions.

It seems that Zipp is saying that a glass smooth wood floor is the cut-off between hooked and hookless with respect to optimal presure for the majority of riders. At this point, that is a very helpful exclusion - for them.

Almost an indoor / outdoor “determination” by Zipp.

However, outdoor testing shows a whole lot of conditions (road surfaces) where pressures over 5 bar is faster. As the article points out most TT and triathlons are held on normal road surfaces as opposed to chipseal or cobbles.

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Dan Kennison

facebook: @triPremierBike
http://www.PremierBike.com
http://www.PositionOneSports.com

I think it is JP Ballard of SwissSide who likes to remind people that the Laws of Physics haven’t changed. So you can’t ignore the A in CdA. Now it would take a real aerodynamicist to tell you if widening the entire tire/wheel system can change the overall shape in a way that Cd is reduced and if that change can offset the 12% increase in A of going from a 25 to a 28.

As mentioned before, reliable test data finds real world situations where the fastest pressures exceed the 5 bar limit, so I think it is incumbent on companies like Zipp to demonstrate that their pressure calculations are correct and that Silca, SwissSide, Marc Graveline, Premier, AeroCoach,… are wrong (as an example, Marc found that Sylvan Adams was fastest on a 23mm front tire during their testing for Master’s Worlds).

I think the real solution to the hookless issue is to reduce the stretch in the tire bead. If hookless tires stayed on at 7 bar there would be no debate that it was the way to go. Maybe we will see wire beads come back in style.

In a previous Post I had suggested (tongue in cheek) that they should use a titanium wire bead, and eliminate the pressure issue.

Quote Ronan McLaughlin @ Escape Collective - "The dimensional conversation highlights one inherent design challenge with hookless road systems. For all the talk of the missing hook, rarely mentioned is the dimensional and customer-expectation hurdles manufacturers must scale in producing hookless road system that is both safe and easy to use from a tyre installation standpoint.


One could argue a truly safe hookless road system should consist of a steel-bead, stiff-walled, non-folding tyre. That tyre should be mounted on a rim with a BSD, flange height, and rim well depth all exactly to standard.

The only issue with such a system is that it would prove all but impossible to install a tyre at home, let alone do any roadside repair that required more than a plug, some sealant, and air. The claimed and debated benefits of hookless road system may exist, but if they do, they do not come for free. The cost is either a thumb-busting process for changing tyres, or a system that allows for easier tyre mounting but is perhaps more prone to tyre dismounts." unquote

...and since moving away from tubular tires, when was the last time you had to change the whole tire while out on the road?

We are in agreement.

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Dan Kennison

facebook: @triPremierBike
http://www.PremierBike.com
http://www.PositionOneSports.com

X2!

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Kiwami Racing Team

Are there issues with pressure for hookless and mid-race flats? Seems like they have a fairly narrow pressure window (high enough to ride, low enough to not have blowoff risk), and inflating with a CO2 isn't exactly science.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

Is the rim brake track still in tact on the new super 9 like it was on the older version even for the disc brake version? It’s had to discern from the pictures.

I think this version is a little more expensive than its predecessor. Maybe $100-200 more.

Is there any aero data that can show the delta between the older (25mm optimized) vs newer (28mm optimized)?

Edit: Is this the first hookless disc? I’m a little surprised zipp came out with one before enve.

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blog

I’m far more offended by the $3,000 price tag than hookless. 😁

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Favorite Gear: Dimond | Cadex | Desoto Sport | Hoka One One

i think what you might find in the future is that max pressures for hookless will scale with tire size. the 5 bar max was pretty arbitrary. i think that'll get tuned. however, what i think you're likely to find is that 5 bar for tires 28c and larger is plenty enough for almost all people in almost all use cases.

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Dan Empfield
aka Slowman

i will share any data i have. i wasn't in kona or nice last year; i think i might be able to help get tire size counted. just, it's hard to count. you have to almost just ask those taking their bikes in what tires they're riding. or, if it's just the pros ask them prior to or after their races via some other contact method.

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Dan Empfield
aka Slowman

i'm not convinced of this. if you're talking about 28c and up. i don't think we've yet had that much testing on a 28c tire for TT applications. for Crr, that 28c tire in, for example, silca's calculator swells to 30mm when you put it on a hookless road wheel, because those wheels have such wide bead widths and silca specifies measured width. you have to get to a very smooth road before you exceed 5 bar on a 30mm measured wheel. and that's silca, which is going to yield higher pressures than what the manufacturers say their pro teams are using. i think this is one of those areas where we must agree to disagree pending some moment where those testing generate more agreement in their results.

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Dan Empfield
aka Slowman

I am no marketing guru - but why the heck did they not give it a new name. Now, trying to buy this online, people will struggle to figure out if this is the new or the old Super 9. Shoudda called it Sub-8 :)

I find it interesting that with NO DATA, we are claiming what is better/faster........and "I told you so".

"i don't think we've yet had that much testing on a 28c tire for TT applications", yet we're talking about a $3000 disc wheel for Tri and $2000 NSW wheels for Tri. Are we not ?

"pending some moment where those testing generate more agreement". If nobody shows their data, we will never get agreement. We have no data.

I have not seen any data on roads that resemble those used for TT and Tri. I have asked, nothing, nada.

I cannot release all my data. It belongs to the teams and the athletes and I know the team will not release it and I don't plan to ask the athletes. I can gladly talk about protocols to feel comfortable they make somewhat sense.

What I can release are "aggregated" results: very simply a 28mm tire (size on label), on a hookless rim, on a typical AGer, on a good bike path has an optimal tire pressure above 5 bar. This according to my results, which could be completely flawed. I don't pretend to have "the answer". But I do think what I am finding needs to be confirmed. I have also spoken to WT guys and they go "ya, that makes sense".

Speaking of WT experience, yesterday at breakfast a bunch of mechanics at the hotel were sharing their stories on hookless, tire recalls, disc brake specs, how they see things at 1000x the speed consumers do. That is worth an article all by itself.

I have quantified it for several riders, it's in single digit watts, but it's waaaaay more than the marginal aero benefit of a hookless interface.

The protocol could be optimized, how much you're leaving on the table should be better quantified.....there is definitely more work to do here, but it doesn''t seem anyone is interested on hard data.

We can do all kinds of mental gymnastics to get Silca to spit out a number below 5 bar. I never said Silca was right, I said my results are more like Silca than Zipp that chooses to ignore road conditions.

Dan, have Zipp send a wheel to Ronan. He is aware of the protocols, he has the equipment. Heck, send him the wheel and I am sure he'd come to Girona and we can find some interesting riders to test.

I did order myself a disk brake bike, just for hoots, to do more testing. There are things I've wanted to test as an AGer for a long time so I talked my Plasma 3 TT rim brake bike to share the garage. The tests are targeted to AGers wanting to quantify the BS level of some of the claims being made by manufacturers. Interesting enough, I was speaking to one manufacturer about something else, stumbled on my little project and he said "here, make these part of your experiment, no strings attached". That was cool.

i guess you must agree that it is likely that the companies you talk to are not 100 percent transparent as they dont want to throw their product under their bus
it sounds to me zipp told you 25 mm was fine, now it sounds they dont say this to you anymore so we cant deny that they where likely not too upfront with you or had mistakes in their protocol .
its a bit like how enve said a rear disc is not faster until they produced one and suddenly it was faster...

btw what is the accuracy of the inbuild pressure gauge , ie i see this as something potentially very useful. how easy can it be replaced and at what cost.

so i think you would be wise to take your claims a bit back until you have really solid data that backs up your claims. if you are interested in a evidence based approach and not just your gut feeling.
just to be sure i am not saying you or the companies are wrong far from it .iam saying at this stage the only solid answer is further research is needed. and till then i guess only people that have done proper research should share their experiences and a maracg does still with the cavet that this is not the conclusion yet... which is good science i would think .

A $3000 disc wheel that isn't lenticular and requires a 60psi 28c (or wider) tire. That's a bold move Cotton. I'll bet they sell tens and tens of these.

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Dimond Bikes Superfan

At least they have finally got rid of that terrible sticker cover and copied DT Swiss' removable hard cover.

On this same vein, how much is it actually cheaper to manufacture these hookless rims, compared to the same model hooked? I have to guess based on wholesale/direct sellers that the cost to manufacture a single rim ends up at less than $100 (not counting any R&D, QC, shipping, anything like that). Removing the hook isn't going to remove material cost, but could reduce tool and labor cost. I have a hard time seeing the total savings at more than ~10%, but I really have no idea about such specifics.

The point is the manufacturing cost savings surely must be significant for these companies to take on such a risk and continue to push the product in the face of majority opposition. Like, why would Zipp continue to push the narrative by making a $3000 disc wheel with an 80psi limit if they only save $15 in cost? Seems like surely a hooked rim would capture a greater market share.

from inside the asylum i can report that zipp's 303 S is really causing havoc among premium wheel makers. it's just impossible to compete with this wheel if you're a premium wheel brand trying to get OE spec. so, yes, the cost/benefit of hookless is evident in this wheel. but there's a limit to this. the cost of materials, mold making, labor dwarfs the savings you get by getting rid of the bead hook.

as to why zipp feels that it's worth the risk to cheese off 75 percent of its skeptical customer base, you're right. it's not because it's trying to save a few bucks.

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Dan Empfield
aka Slowman

Do you have a feeling how much of the hookless premium wheels are about differentiating oneself from many other manufacturers doing hooked? (I find it very hard to differentiate marketing vs truly believing in this tech as better for tri/TT with the limited available data.)

And whether the 303s should be seen as a loss-leader from zipp, getting more people used to and trusting wide hookless rims? (it has great value for price compared to other hookless offerings which are very premium)

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https://besse.info/
https://www.strava.com/athletes/2012033

Yeah a $600 wheelset is in line with what direct to consumer Chinese brands are charging. It's puzzling tho because other Zipp wheels don't have such a markdown. The economics just don't make sense to me here. The only way I can wrap my head around it is if Zipp already had long term contracts in place with bike brands to supply wheels for their builds. In such a case with guaranteed sales then cutting costs starts making sense.

To the later point, if it's not trying to save a few bucks then what's their actual motivation? Do they truly believe that hookless is faster than hooked? Surely such a stance would be backed up by robust data. Data which hasn't been corroborated by independent testing. The whole situation is just weird.

TL;DR - It looks like hookless for road and TT bikes is likely inferior to hooked and is a solution in search of a performance problem.

I just read many of Dan's & Ryan's hookless commentaries and interviews on the home page. I was this many days old when I learned that the hookless controversies and objections may have some meat on them. It seems like it is more difficult to get a setup system that complies to the "Rule of 105." And experts that do testing for athletes and teams are still leaning toward hooked setups for the fastest solutions. Further, it seems like the manufacturers, standard makers, and marketing messages did not keep pace with the exuberance of saving a few bucks.

Ultimately, I do not care, since the hookless and tubeless setup on my road bike is for comfort, not speed. And I am unlikely to have a blowout at 60 PSI. But, I am now less likely to consider hookless on a TT bike until this all coalesces a bit more.

I've seen testing between a HED Jet+ disc and a Zipper Super9. Let's just say, I'd save your money and get the Jet...

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Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook

I think you are right, it will be plenty enough for almost all people in almost all cases except……for tri and tt.
At least as for now.

The testing we did on several riders on hookless wheels, agreed, on a pretty good riding road surface, showed with no exception that 28 mm gp5000 tubeless set up on cadex 4-spoke and/or cadex disc wheel they were fastest at 5.5 bar, second fastest was 5.0, third fastest was 4.5 and slowest was 4.0 bar. The 28 mm tire measures a little over 30 mm on the wheels.

And we knew the 5.5 bar was out of the limit but we took the risk just for comparison sake.

Within a couple of weeks I will do some more testing most likely also with the Zipps incl. this new disc wheel

Jeroen

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Owner at TRIPRO, The Netherlands

Just like the new super shoe market with shoes costing more than $250, I can't believe there is ANY market for a $3000 wheel. The cost/benefit analysis of this breaks my head.

I guess that is why I still race duathlon/tri on a Flashpoint 60 with a 20mm Supersonic tire with a rear, spoked Powertap wheel and a cover. The pain in my legs always makes me forget the road is occasionally rough.

And that is from a guy who is all in on big tires for ever other application. My road bike uses a 38mm Challenge Strada Bianca at 30 psi and I would never go back to skinny.

i can only tell you how i decide on the wheels and tires i choose. my imperatives are these:

1. my very first decision is tire width. this drives so many of my bike and component decisions. this is irrespective of who makes the wheel or tire. i choose my desired tire width and for performance (racing) it's 28c blown up to a 30mm measured width (and that's whether road, tri, tt). for everyday riding (on a road bike) i'm riding at least 30c, usually 32c, which blow up another 2mm or 3mm in width when inflated on the wheel i'll choose.
2. this informs my pressure choice. 60psi on the 28c and 50psi on the 32c (42 to 45psi in that tire if i'm riding light gravel).
3. this informs my wheel style, which is going to be hookless because the pressures i'll ride don't come close to exceeding the 5 bar hookless limit so i may as well take advantage of the advantages in a hookless wheel. it also informs my rim width because i feel the sweet spot for road is a tire with a rim width about 5 to 7mm narrower than the nominal tire size. this means 23mm more/less for performance wheels and 25mm (this is inner bead width) for everyday wheels.
4. then it goes to brand. i'm picky about choosing a brand that doesn't just make a hookless wheel to be new or cool or because it's the trend, but makes a hookless wheel because it recognizes the benefits of hookless and manufactures to those benefits (stronger rim, better resin penetration and so on). and, i want a manufacturer that's done a spitload of blowoff tests so that it knows that its rims can comfortably hold a tire (enve's rims have to hold a tire up to 165% of its max pressure, cadex to 200%).
5. then, in tires, i pick a tire that i'm comfortable with. for me, it's vittoria, cadex, goodyear and a few other brands that i personally use, have confidence in, and that i know has good manufacturing control of its tire bead (specifically, that the bead is not stretchy). you're fooling yourself if you think a tire with an overly stretchy bead will come off a hookless wheel but remain on a hooked bead. it'll come off both. the bead hook will give you an extra 20psi or so if safety. that's it.

i don't think the 303 S is a loss leader and i'll tell you why: i've begged SRAM for years to loss lead on some of its products. for example, wireless blips. i think they should darned near give those away to OEs, because they're a great bar-end shifter and they open the door to the same of the entire groupset. but they resist this every time. it's just not something they do. i think they just make a lot of those wheels, and they design and manufacture them as a high-end OE wheel, with economies of scale, and can deliver them at that price. SRAM and daughter company zipp have OE dialed. it's a core part of their business. premium wheel makers have a hard time just logistically competing (e.g., getting their wheels over to taiwan or china for complete bike assembly).

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Dan Empfield
aka Slowman

thanks for engaging. i just got back from sea otter last night. i don't know why SRAM wanted to launch its disc during sea otter. this makes it kind of hard to pay enough attention to this if you're writing this up for an audience because you're... busy with sea otter. so, i omitted the data part of this in my writeup of zipp's new disc. now that i'm back i'll present what i have and i'll tell you what i do NOT have that i wish i had and that i will try to get from zipp. give me a day or two.


i don't think my presentation of silca's results are contorting the numbers to fit a narrative. i've just been looking at why there is a disparity between various recommendations, and in my attempt to reconcile them i felt that the big delta is that many people - i, for one, and suspect i'm not the only - see "measured tire width" and think screw it, there can't be that much difference between named and measured, i'll just go with named and call it good.

but in fact the tire makers name their widths based on a 19mm inner bead width and that's on NEW tires recently introduced (any tire in a mold a couple of years old or older probably measures true to a named size on a rim with a 15mm internal width). all the hookless makers are using 23mm and 25mm internal bead widths. this grows the tire in width by 2mm at least beyond its named size. that's a pretty big difference and just right there you drop 10psi from the silca recommended pressure (if you use measured instead of nominal). at this point the silca recommended pressures and the pressures the manufacturers recommend are pretty close. silca is still higher, but by maybe 5psi or less.

then you have this other thing - which you test - and when i imagine how you test i believe i can see how your testing would exceed the chung method in accuracy and utility, because silca used a freshly paved road for its testing. so freshly paved it was still closed to traffic. for a discrete stretch of road, a few hundred yards maybe, just paved, there are no imperfections. then you move this all to a race course - and IM let us say - and you have some really great roads. but then there are stretches when the roads aren't so great. but you can't change tires or tire pressures during the race. the manufacturers - and their world tour cyclists, they say - err on the side of the imperfect sections of perfect courses because what they lose through overinflation during those stretches dwarfs the very small gains extra pressure gives them on the glass smooth road surfaces elsewhere on the course.

i'm relating. not advocating. in my own riding, i'm in an area that freezes. we get freeze cracks on our asphalt and at its worst it's like riding over railroad tracks. we have quite good roads in general. but the freeze cracks, and these sections occur here and there, with transverse cracks in the asphalt maybe 20 yards apart for stretches, are really not worth trying to get the extra pressure in there to deliver the extra watt on a smooth road. if i knew a road was perfectly smooth the whole way yes, i'd throw more air in there. i just don't have much experience riding a course that is uniformly paved that way. kona surely isn't. nor is oceanside, arizona, texas, placid, penticton, nice and so on. for sure, i understand that your reality is different. discrete TT roads in europe, closed to traffic, in countries that care enough about their pavement to put the good stuff down. not so where i live ;-/

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Dan Empfield
aka Slowman

You lost me at 30mm wide (actual measured width @ 60psi) front tire for TT.

Look at the HED Vanquish 28 v. 25mm data from the other thread, the difference in drag for the V84 at 0 degrees looks to be less than 10grams at 30MPH. That's probably less than 1W. And 30MPH is faster than the average speed of most of us in almost any TT/tri. And once rolling resistance is factored in, might be a wash. That's before comfort is even considered.

That's just 0 deg. Didn't have the patience to look angle-by-angle. Also tough to read the graphs with less than ~5g accuracy. Also, just the new HED Vanquish, obviously. I do inherently trust that HED's graphs are based on real data, though. I don't know what the data is, e.g. what pressures the tires were, what the WAMs were or casing tensions were. But nevertheless real....

So, um, how does it ride for guys over 200lbs? Does it blow out immediately? Read the article, did they actually do rider tests with the rider at 230lbs?

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Washed up footy player turned Triathlete.

I’m trying to bring the topic back to the use of the new Zipp wheel, a disc wheel, built to ride with speed and for races. I have never raced in the US so can’t comment on the road surface there. It might be as bad / worse as you say, I don’t know. Let me take this wheel to where I live and we have very good roads for cycling and for sure on most race courses for 90-95% of the course.

So for us the use of this wheel is speed. Using Silca’s calculator it still spits out pressures thar are either out of limit of hookless or barely within the limit. When I choose rider and bike at my 87-88 kg, choose a top tubeless tire in 30 mm width and new pavement it gives me 5.15 bar and 4.85 bar when it is worn pavement with some cracks. Only really bad pavement gives a value that comes close to the pressure that is actually the normal value advised by either Zipp, Enve or Cadex.
The 28 mm width tire on a Cadex disc wheel or their 4-spoke wheels measure 30 mm, but even choosing 31 mm makes little to no difference.

The use of a disc is to gain speed, nothing less or more, just speed is the main goal. The question is is hookless then the right choice to built a disc wheel on if it limits it range to 5 bar pressure. Am I willing to sacrifice 3-5 watts, maybe 6, on a wheel that sets me back $3000.

The thing I find really interesting is that their also brand new disc wheel for track with 21 internal rim width is built hooked so it can be used with 23 mm tires at 8.6 bars.
What data of testing could they have that they still decided to make the road disc wheel with 23 mm internal width hookless but being limited to 5 bar pressure.

And if they have data that proofs that this wheel tests faster with 28 or 30 mm tires at 4, 4.3 or 4.5 bar then on a hooked version with the same built dimension, same tires in type and width but at higher pressure why don’t they provide it?

I’m not buying a disc wheel because I want a comfortable wheel, at $3000 I want the fastest that is possible, agreed?

Jeroen

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Owner at TRIPRO, The Netherlands

yes, you want the fastest wheel. bearing in mind that, over 56 or 112 miles, comfort is a component of speed. but yeah, what you want is the fastest time.

i don't stipulate to the silca calculator for these wheels we're talking about. i stipulate to that calculator for a tubed wheel, not a tubeless, hookless wheel. but i think the silca values are instructive. even tho the silca values are slightly (not much) higher than the wheelmakers themselves recommend and their pros ride, if you take my own edge case and i'm 77kg, if every single choice i can make in the silca calculator is geared toward a higher pressure - new, smooth road throughout, highest speed tires, choosing a talent option that's above what i actually am, i still end up right at 5 bar exactly. what the wheelmakers argue is that in fact ideal (for speed) pressures on their systems don't even approach 5 bar. i think this might be why marcag's testing differs, because he's not testing his riders on these systems. but i don't know.

i think this is going to be a pivotal year in cycling. if you see a lot of results on these wheels/tires it becomes harder to argue that you're giving up speed if you ride them. you can't argue that chloe dygert can ride this system because she's a woman. she's probably the size of the average world tour man (or larger). there's nobody riding faster than she is in timed racing and she's riding a tire that measures 30mm front and rear on these *slow* systems.

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Dan Empfield
aka Slowman

First of all, we should stop with the Silca calculator, it is a guideline. I have simply said my data is more in line with Silca than other calculators. We should rely on test data.

Second, "marcag" data does not differ because he's testing rider on different systems. I have tested on hookless 22mm internal rim with and hooked 23mm internal rim width. Both busted the 5Bar limits.

As for what the WT riders are riding, yes, absolutely they are going wider. A lot are on 28. The wheels are being optimized for 28. But I spoke to a senior technical person on a WT team riding hookless. He acknowledges the majority of the peloton is riding higher than 5bar in TT. His words : they are riding between 5 and 5.8. We both acknowledged that teams are often willing to make compromises to satisfy sponsorship needs.

A person forking out $3000 for one wheel does not need to compromise.

Speaking as someone that was in the market for a new disc, I agree. Flat sides with a dimpled pattern (without any data) at 3 grand is woefully out of touch in my view. Their brand name is no longer strong enough in my view to take what is essentially a 15+ year design, make it wider and suddenly expect to be seen as leading edge.

Maybe Dan can clarify, but by "different systems", I thought he might be referring to SRAM's "rolling road" test, or similar.

thank you for the clarification. and for your participation in this thread. you're a good sport to indulge me.

you're absolutely right and i'll go further: whether i'm forking out $3000 or $300 i don't want to have to compromise. i'm glad you brought up optimization. i am routinely disappointed when i go to industry events and it's clear by the display that the brand folks in charge don't understand the features of the product(s) they make. i was heartened by the display in zipp's booth, where they're showing this new disc, because this BMC tri/TT bike is one case where the entire bike, from the frame to the wheel to the tire, is an optimized and fairly mature system. i think you can see how that is.



from disc brakes to tubeless to the whole wider tire thing i've always been at a disadvantage because i'm arguing in favor of the system when the system doesn't yet exist. disc brakes in tri bikes. questionable idea in 2016. until the system emerges that absorbs that tech.

so, i think we'll see a lot of 28c, which measure 30mm on average, on TT and tri bikes and they'll work now because all the new road bikes and most of the new tri bikes are optimized for this size, as are the wheels. this is why a tire of that size doesn't give up much if anything in aero, and wins big in Crr, handling, comfort. as for road, 25c is gone, even if some people don't know it yet. i think you see this in your own work with pro teams, yes? the working size in mass start racing is from 28c to 32c depending on road condition. this was inconceivable 2 years ago.

as to pressure what i'm hearing is that pro riders keep asking for wider rims, lower pressures, wider rims, lower pressures. but that's for this time of year. spring races. on the TT side, you would know more than i do. i don't find 5.8 bar scary or risky because i ride mostly zipp, cadex, enve and vittoria, schwalbe, cadex tires, goodyear, i trust all those combos to be safe at any pressure up to 85psi (notwithstanding the ETRTO's guidance of 72.5psi). if i was riding a different wheel or tire i might conclude differently. i personally don't ever feel a need in any of my riding, any use case, to exceed 65psi but it would be silly for me, where i sit, to lecture you on your business with your teams.

but there is one thing i would like to be clear on. there are tire brands i'm not listing above and i don't only avoid some of these brands for hookless, i avoid them for hooked. the safety issue isn't hooked or hookless. the safety issue is just the tire itself, regardless of the rim type.

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Dan Empfield
aka Slowman

   





And I thank you for not banning me for being a dick at times. The Canadian side of me is nice. The Frenchman side is argumentative.

Talking to the guy that was on hookless and believed he was leaving a bit on the table, they have been told, very clearly, 4.9max. Period, end of story. Now, will they bend the rules if they are off the podium by 10seconds on the last stage Monaco to Nice ?

You mentioned a bunch of brands there. One mechanic of a hookless team I was speaking to was responsible for making sure the pressure in the tires that go on the roof racks had .5 bar less in them because they were popping in the sun. His completely unscientific opinion was that it was tire related not wheel. He explained why, I can't disclose, but he really put suspicion in my head.

Here's a tough question : tomorrow morning I have to buy a disc. I will go 28, fine. I am a billionaire, money is not object (this is an imaginary situation). Why do I go with the hookless Zipp wheel where I may be borderline vs the HED hooked wheel where I have 0 to worry about ? If it was gravel, I don't care. Cobbles or casual road riding, I don't care. But I have a TT or Tri to do, why do I take the hookless wheel ? Maybe I'm too fixated on the 72.5. Which is strange because I always considered speed limits on the road as recommendations rather than rules.

Been lurking on these threads. Dan you have shared your imperatives, and your preferred set up, several times.
Would you mind sharing your weight, kitted up, bike and bottles, heading out of the garage?
For the euro folks, who do indeed have better roads, a few photos of your typical riding surfaces, and a few of the more impressive frost heaves, might prove interesting.

Here is one of the great European silky smooth roads we test on

There are many here who have far more industry insight than me - my opinions are largely based on what I see happening in the real world.

There are two Time Trials in this year's TDF - neither having an uphill cobblestone finish :-). We won't really know how much pressure is in the tires. We won't really know if they are riding special one-off tires not available to the public.

None the less, if anyone gets on the Podium with a 30mm wide (or wider) front tire in those TT's, in ST's spirit of putting your money where your mouse is, I will send Slowman a crisp $20 bill.

Totally true, comfort, this is the variable on 56 or 112 miles that is very hard to quantify in how much it is going to cost -or not- in time / speed.
And as said before, I own a Cadex equiped with the hookless 4-spoke wheels and also a Cadex hookless disc wheel. The one thing I don’t get, still don’t get, is why would a manufacturer choose hookless over hooked as a way to built their wheels when hookless is limited at pressure and hooked is not. Well, not at 5 bar. Although the new HED new hooked wheels are also limited in pressure pretty low.

I’m completely on your side for normal road riding, gravel etc lower bar pressure is very comfy and nice. For tri / tt it would be great if brands could deliver hard data that shows that hookless built delivers a speed performance factor that could not be meet with hooked built.
They could even specify it by the use of different tires, the main used by either pro’s or what a majority of AG use.
If I want to pop out € 2750 for a Zipp disc wheel or even more for the new HED wheel I would like to see ‘hard evidence’ that I’m buying the fastest available. And not the fastest within the limit of what the rule is due to the way the wheel is built but ‘could’ have been faster if the wheel was built differently.

And the new track disc wheel by Zipp with a 21 internal width and hooked to withstand higher pressure/smaller tire at 8.6 bar. I would not say a good road pavement is the same as a super smooth wooden track but it seems like there is some middle ground left in between those two.

Jeroen

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Owner at TRIPRO, The Netherlands

You keep mentioning the pressure calculators but they are all just starting points or recommendations. And only one of them has multiple road conditions for tt/tri riding. I don’t think any of the calculators, including silca, are 100% correct. Theres too many variables from rider to rider and road to road for any of those calculators to be 100% correct 100% of the time. So I think we need to put them aside as they are a tool and not the end all be all.

Also, I don’t really buy that WT teams are riding exactly what zipp, enve, cadex calculators say. Are they close, probably. But it’s going to vary based on the day, road conditions, weather, etc. I’d also say that we need to put aside what they do during road stages and instead look at what they are doing during TT stages.

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blog

Please correct any of this

The guys on Enve (UAE) end up using non Enve wheels for their top guys. They use hooked
The Cadex guys (Jayco) are still on rim brakes, They use hooked.
One of the Zipp teams claim they run at 4.9. The UCI said they have to, so I bet they have to say that.

As for the claim Movistar rode them to 2nd in the TTT last year, it was pooring rain.

I’m potentially in the market for a disc with exactly these specs, but I’d still like to see some solid data on how much faster this would be than my current gen 808 rear wheel .

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"When the going gets weird, the weird turn pro."
Hunter S. Thompson

on the tires: i am quite confident that none of the hookless wheels i ride for the road would lose a tire at anything remotely close to 5 bar. 7 bar then i'd begin to be concerned. otoh, a tire that would blow off at 6 bar on a zipp or cadex wheel, you're dreaming if you think that tire is safe on a hooked wheel. there are just unreliable tires, in my opinion, and i suspect this began with the move to road tubeless. the issue is the bead. bead stretch. but i'm not going to name specific tires or brands because it's just my opinion and i don't think it's fair to throw a brand under the bus without the kind of evidence i don't have.

on the disc wheel i'd buy tomorrow morning: i'm going to ride tubeless. so, discs that aren't tubeless optimized are disqualified. second thing, 28c tire. third, at least a 22mm inner bead width. i'm not riding 5 bar so zipp is not disqualified. whether i buy a zipp or a HED now falls to other considerations. is it aero? does it fit my budget? i would just go down the list of imperatives, disqualify discs that don't hit my thresholds, see what remains, probably buy the cheapest one.

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Dan Empfield
aka Slowman

i'm 170lb, the road bikes are around 16lb so that plus bottles and so on.

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Dan Empfield
aka Slowman

why don't you send me a 20 peso bill now, since at least 2 of the 4 marquis winners in last year's UCI world TT championships (overall and U23 mens and womens) were on that tire width front and rear.

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Dan Empfield
aka Slowman

 
And none of the top 10 in last years TDF TT

I thought someone posted on another thread that these were Enve prototypes:

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blog

I believe they are Aerocoach AEOX

Ah. Maybe I misread that thread/post or imagined that for some reason. Looks exactly like you said. Thanks

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blog

yes, they didn't use enve wheels.
however enve's disc and deepest front (7.8) specs:

• Inner rim width: 18.5mm / 19mm
• Aero Optimized Tire Size: 25c
• Hooked

so the reason they choose non-sponsor wheels has nothing to do with hookless, tire pressure or tire width.
UAE chose enve as their wheel brand for road stages (where they do ride hookless etc) before arranging sponsorship.
for TT they choose aerocoach but none of that is relevant to the current discussion either way aside from Dan's potential $20

This is about 10 steps more than anyone thinks about when buying a set of wheels to race on.

In a 2500 person triathlon < 1% of people have a decision tree like you do.

maybe 1 in 500 think about inner bead width but probably more like 1 in 1500. 1 in 200 think about tire width, probably more like 1 in 1000. almost everyone is going to buy because they recognize the name, then they are going to slap the tire on there that their bike shop tells them to or they can get on sale.

Why do you think you see so many gatorskins on a set of 808's?

I've aero tested pros, pros who have won more than 1 race last year and people in the top 5% of triathletes thinking about their equipment. They didn't know they were on hookless wheels.

You are the 1% of 1% of triathletes. Let's talk about the other 99+% and how they actually buy wheels to race on.

That's why hookless is a dumb fucking idea

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

No. You read it correctly. It confused me too as those are clearly Aerocoach wheels. The poster reps Enve for marketing and is tight with their team. Maybe he received some incorrect info on what was available to the team vs. what was used that day?

I’d guess your personal hookless TLR list is similar to the list Enve posts for their wheels. Their list is from testing the tires on their wheels. They even recommend pressures higher than the new standards for some of the rim and tire combos. I assume these came from straight up testing.

The aspect of their list that stands out to me is how short it is. The other concerning aspect is the lack of the fastest rolling tires on their list.

Personally, I’m all in on tubeless for all my bikes besides the TT/Tri. I’m mostly all in on hookless for these bikes too, just because I’ve historically used Zipp and Enve brands due to warrranty and customer service. Some of this tubeless transition also came due to lack of recent racing for me. Like Trail posted previously, after years of balanced riding between TT and road/gravel bikes, I now find myself picking the road/gravel options due to the more comfortable TLR tires.

At the same time, I’ve had to keep my wife’s equipment updated for tri racing as she’s never stopped competing. When we updated her to a new bike, it was disc brake. So, new training and race wheels. She uses Zipp and all they offered last year for deep wheels was hookless. A lot of the concerns expressed in this thread aren’t an issue for her cuz she’s small and prolly lighter than all but the tiniest of Marcag’s UCI WT tested riders. Zipp is at 23mm internal for their deep race wheels (last year’s disc is 19mm internal).

The biggest bummer I noted when setting her up, was that Conti’s newest hookless compatible GP5000S TR and GP5000 TT tires in the 25mm width are not compatible with an internal rim width over 21mm. So, a 23mm internal width Zipp rim requires a 28mm or larger Conti tire. All of Conti’s tires larger than 25mm work with 25mm internal rim widths. This was a surprise to me. They skip over Zipp’s racing wheel standard of 23mm internal completely. Schwalbe is less conservative and does list their 25mm race rubber as 23mm internal rim width compatible. We’ve used these and in addition to rolling a little slower they proved less puncture resistant and don’t seal well so they are no longer an option.

That shouldn't be a bummer. She should be on 28 because of the 5 bar limit.

We tested a 59kg woman on hookless 22mm internal.

She was running Conti 25. Her optimal tire pressure on a good surface (Kona like) was over 5 bar. We only tested to 5.5 bar for safety reasons. At 5 she was giving up 4watts. She was a Kona AG winner. I suspect on a 28 tire optimal would have been a hair under 5 bar. Still borderline IMO for a light female.

It's a data point of n=1. Finding the heavy folks for testing is easy. Next session needs to be all ladies. Anyone have Chloe Dygert's number ?

Paging Jim.

Are lenticular discs more desirable for some reason? I've never read on the topic of lenticular vs flat. Got any resources/links?

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Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

That doesn't happen on race day for real... right?

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Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

didn't your daughter just start racing ? She's light....perfect for CRR testing

it does the most famous would be andy potts

I used to love walking the racks the day before a major race. I used to make fun of bad decisions aka people's bikes on my IG account. There was just too much content.

The average triathlete who is showing up to challenge themselves, wants to finish yet isn't there to crush the dreams and hopes of others often makes a lot of less than ideal decisions about their bike set up. Yet this isn't exclusive to that group. It happens from the pro racks down. Some people, a lot of people actually, just make the race harder for themselves.

I'd say at any 70.3 < 50% of the field has actually optimized their setups even if >50% of the field thinks they have

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

She's in the U-5 category on an optimized Woom bike setup. Aero AF!

Andy Potts is nervously lurking here eyeing up the Gatorskins comment.

I was going to comment I've never seen Gatorskins on a set of 808s *except* Potts. In like 20 years.

Generally slightly more aero. Though some knowledable people here have said that flat tests better with some frames/body positions.

if i'm asked about how others decide on which wheels they'll buy i'll answer that. i was asked how *i* would choose a wheel and i answered it that way. i don't think my imperatives are that obscure. tubeless. is that obscure? selecting a wheel that accommodates the tire i intend to ride? if that's way beyond the scope of the typical disc wheel purchase okay. i just am surprised by that.

as to what are dumb fucking ideas, based on the views voiced here on this forum from leading industry influencers just think how much faster some of these guys today could go if they went back to latex tubes in 23c tires on rim brake bikes.

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Dan Empfield
aka Slowman

"latex tubes in 23c tires on rim brake bikes."
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hey - hey - hey!! You are getting personal now (Although I have evolved a bit) . . . session w/ Desert dude this afternoon :-)!

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David
* Ironman for Life! (Blog) * IM Everyday Hero Video * Daggett Shuler Law *
Disclaimer: I have personal and professional relationships with many athletes, vendors, and organizations in the triathlon world.

I think about inner bead width a lot when looking at wheels. But where I'm significantly different from Dan is that I'm racing at 205-215lbs. Maybe one day I can get back to 190lbs, but sitting at a whopping 230lbs right now I don't know where that is. I think I've had only one person actually reply to me about hookless with a real answer. (larger inner bead width allows me to use a bigger tire at good pressures, take HED Ardennes, 90ish PSI, the only time I'm running less pressure than that is what going full gravel and 32mm tire?) Either Fredly or Rappstar, and their answer was...yeah you're pretty much effed. This might be the first wheel that is rated for big guys in the hookless development. Think about how many wheels have hit the market that will effectively explode if the rider is 185lbs? And not so much as a reply to this concern when I've asked Dan. I'm not being a dick, but I am trying to make a point. We have wheel companies trying to mass market, through Dan and other reviewers, wheels with limited markets and use cases. Unlike super shoes, the market for this wheel is like two people at IMAZ. And both of those dudes are brain surgeons and weight 165lbs.

But hey, let's keep pumping out the orthodoxy that hookless is somehow better and cheaper...when in fact all we've done here is toss millions(?) in RND costs that could have gone to making better hooked wheels? Hooked wheels that would obviously still work for the 195-215lbers?

Thanks for the post, it made a significant point for me.

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Washed up footy player turned Triathlete.

You know, if you're going to do something, do it right -

"Let's go back to 23c Tubular Tires with Latex tubes, and disc brakes."

Tubs were wonderful! Track, Road, TT, Cross - all great! I had always hoped the early switch to disc brakes would have caused a resurgence in their popularity by removing the rim heating/glue melting issue of rim brakes, but clinchers were already too entrenched. That, plus they have always been (for all practical purposes) unrepairable - somebody should have figured out how to put a zipper in them! I sure do miss them.

Let's all remember Management 101 - NO personal attacks. This is not brain surgery, and ultimately the success or failure of hookless will be determined by the marketplace. What we discuss here will have very little (or no) effect on that outcome vs. (for example) a YouTube video that will have thousands and thousands of views in as little as 24 hrs.. My $20.

if you look at the discs people are riding these days i'd say it's the toroidal ones are better than either. this is - again - something that HED pioneered.

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Dan Empfield
aka Slowman

<<"Let's go back to 23c Tubular Tires with Latex tubes, and disc brakes.">>

this!
I love having disc brakes and wider tires on my road bike, haven't and don't plan anytime soon jumping to tubeless on it.
My Tri bike is a different story, 2nd Gen Trek Speed Concept. Too much invested in wheels to change there. Race set up is a HED Stinger 6 on front, and choice of HED Stinger 9 or Zipp Sub 9 disc both with Powertap hub, all sew ups (tubulars), then training is a set of HED Ardennes with a Powertap hub that are clinchers.


Interesting note, at Toughman LC a couple of years ago in NY, I hit a pot hole so hard that I got a front flat, surprised it didn't kill the rim. It would have also surely flattened a tubeless as well. In comparing my bike computer time (that stopped when I stopped to fix the flat) to the official results, I was down for 2 minutes even changing the tubular. Doubt I could changed a clincher or fixed a tubeless in that time.

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Mike Plumb, TriPower MultiSports
Professional Running, Cycling and Multisport Coaching, F.I.S.T. Certified
http://www.tripower.org

completely understandable. but i don't think that's the point. the truck i'm driving is 6 years old and i have no plans to buy a new one any time in the future. my wife and i are celebrating 18 years of marriage today and i don't think she intends to upgrade to new tech. but that doesn't mean i would prefer that my next truck and my wife's next husband (if it came to that) wouldn't benefit from technical upgrades. the question is: if you bought a new bike now would you buy it with rim or disc brakes? tubed or tubeless? electric or mechanical shifting?


perhaps. i still ride quite a few miles. i haven't gotten a flat, road or offroad, since 2019. that is coincidentally when i move to tubeless across every platform (road and gravel).

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Dan Empfield
aka Slowman

<<my wife and i are celebrating 18 years of marriage today>>

congrats! I still remember being there on day one in the compound amphi-theater

<<if you bought a new bike now would you buy it with rim or disc brakes? tubed or tubeless? electric or mechanical shifting?

good question and I think about it often after we upgraded my wife's bike to a new SC.
Definitely would go with disc brakes and electronic shifting (both my bikes have Campy SR 12 EPS), not sure if I would go tubeless though. Getting ready to build a new road bike once I decide on a frame and might try tubeless on that first. BTW new road bike will be hydraulics in lol

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Mike Plumb, TriPower MultiSports
Professional Running, Cycling and Multisport Coaching, F.I.S.T. Certified
http://www.tripower.org

IIRC the toroidal ones were meant to mimic the trailing edge effects of lenticular discs that weren't possible because of the width of the cassette.

Jumping down a light conspiracy theory hole here. Are we convinced that teams are actually running hookless, and not just running hooked versions with stickers put on to match the consumer facing hookless pairs? Less out there, are we convinced that teams are actually abiding by pressure limits? It wouldn't take them more than 10 tires and an hour of time to do blow-off tests with a specific tire and get their own data set. Maybe 28mm GP5000's are actually safe on certain Zipp wheels up to 100psi.

TBH if I was Dygert (or anyone in that position) and a 5-10w loss is the difference between winning Worlds or finishing off the podium I'd be taking the risk 100% of the time. The difference between finishing 12th because of inefficient tires and 12th because of a blow-out induced bike change is immaterial. Bike racers aren't known for being risk-averse.

We know very few teams are using them for TT at the WT.

I know one team for sure is using Zipp and does acknowledge 5 bar is low. Lots of teams make compromises. It's part of the sponsorship game.

As for Chloe at Worlds. Sure. It was a pretty bad road. I was there doing tests a few days earlier and we dropped pressure on a hooked wheel.

I am sure her weight, that road, she left nothing running those wheels.

Does that one team using Zipp acknowledge and adhere to the 5 bar limit though? I didn't see the details of the road for WCTT but that makes sense. Not a use case I'd design a race wheel for tho.

It's ironic that the fastest riders are the only ones without the true freedom of choice to pick the fastest equipment. It's why the argument "WT Pros run hookless so they must be fast" is such hogwash.

I'm curious if you've ever done testing between wider/thinner tires at the same casing tension (lower pressures with wider tires) or more simply the optimal pressures for that width to see if wider tires are actually any faster. I'm curious as I've never seen that data, and all the data people cite for wider tires being faster is with the same pressure used for both the narrower and wider tires.

For all this move to larger tyres, one naturally thinks you are increasing A in CdA but with an improved tyre/rim interface, does anyone try and calculate the potential aero benefits of a deeper wheel due to increased tyre size. The radius of the wheel is bigger and adds to the wheel depth. I don't know how many mm a 28mm tyre would add to the wheel radius compared to a 23mm tyre, but wondering if this would have much of an impact?

We were more interested in optimal pressure for a given wheel/tire/ride/surface. Each test set was 10 runs at 5 different pressures. The only thing that varied run to run was pressure. Each test set (10 runs) was a different combination of tire width/inner width, rider weight, surface.

There were two test sets where the only thing that changed was tire width. Optimal for 28 was slightly different than optimal for 30 but they tested very close at their optimal pressure. This is a combination of rr and aero. I am not sure just those 2 tests (of 10 runs each) is enough to make a conclusion

GCN did this, although I am not sure how precise it is. They corrected pressure for different widths using Silca.

In theory we could take our "optimal" tire pressure results and use them to feed a fastest tire width test.

i've been digging in the new vanquishes and have been spending some time in a back-and-forth with the designers of those wheels. there are 4 depths, from shallow to full disc. HED has generated data in the tunnel on them all, with 25mm and 28mm tires. this is the takeaway. the aero penalty is so small, and in some cases no penalty and even with 28mm better in some runs, that Crr gains appear to me to overwhelm the very slight aero penalty.

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Dan Empfield
aka Slowman

Where does the "Crr gains" data come from ?

I don't know the specifics but I doubt it has a large impact. You're basically noticing that the chord length of the tire/rim increases with tire size. If it increased linearly you'd see a 60rim +25mm tire / 25mm (3.4x deeper) go to 60+28 /28 (3.14x deeper). Keep in mind also that the tire height does no scale linearly with the the tire width. It's constrained at the bottom by the internal rim width. It's ~75% of width increase goes to height.

Intuitively I doubt that extra height is enough to make a difference. There is probably some speed/depth/width/shape combos where the airflow stalls out or has some weird vortex shedding that is obviated by changing tire size, but this is likely a special case that is unlikely to show differences outside specific wind tunnel tests.

Yes the chord length is what I was trying to get at (just didn't know the term) and if it was making much of a difference. Thanks for your reply.

HED didn't test Crr. don't you think it's generally accepted that wider tires offer less rolling resistance than narrower tires - up to a certain width, with that width being probably 30mm to 32mm - and the limiting factor is aero? that is, at the high end of Crr gains you get diminishing returns, as in, 32mm isn't much if any faster than 30mm, but 30mm is faster than 28mm, and 28mm is faster than 25mm by a yet larger margin. and the smaller the tire the greater the incremental Crr penalty. i take it you don't stipulate to this. i know how it feels to be at odds with the bulk of the illuminati ;-)

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Dan Empfield
aka Slowman

While it does seem there's truth to larger tires being faster, I think the biggest issue is that the effect is extremely surface/pressure dependent, and therefore it's very hard to quantify the actual rolling resistance benefit.

why do you think the world tour pros are switching to 28c for road stages? why are the manufacturers now making their bikes optimized for the 28c size? what's your theory?

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Dan Empfield
aka Slowman

I really don't know.

One one hand, it's a common belief.

On the other, why do they not go wider than 25 when they do the hour record ? They certainly could have.

I have seen data that shows a 30 faster than a 28 both at the same tire pressure. But never a 28 vs 30 at the optimal tire pressure for each on real roads ? Never

BRR showed on their test drums, which are real road that the delta between a 32 and a 23 (huge difference in width) went down significantly as pressure increased.

I believe that if a road is bad enough, even at optimal pressure for each the 30 will be faster. Between the track and the bad road there is a spectrum and I haven't seen anyone show what happens in between.

I do believe you can make a wider wheel as fast as a narrower wheel. But faster ? I'd love to see data.

I don't have enough of my own data (yet) but it certainly isn't obvious, so before I fork out lots of money for a new wheel and a new fork to accomodate my new wheel, I'd love to see some data other than manufacturers claims with no data to back it up. Right now those performance gains are theoretical.

Of all the people in the world that should be able to get such data, you're the man and you don't seem to be able to get it. This puzzles me. The manufacturers certainly have the means to get that data.

I guess I am not a member of the "illuminati" nor a member of the "because the marketing dept told me so". I am more on team "doubting Thomas".....show me the data.

It's obviously because the roads are in worse shape now than they were 20 years ago. Only like 90% joking

With how hard companies are pushing for hookless you have to believe they'd be shouting this data from the rooftops if they had it. Every company tweaks wind tunnel tests to find the one yaw angle and speed where their product is fastest. But on their 'game changing' hookless tech there is nothing. The silence speaks louder than data.

i can only speculate, but i think it's 2 reasons: first, 25 is as good as 28 on glass-smooth resin-covered wood and it's marginally more aero. second, that marginal aero difference at, say, 28mph becomes not so marginal at 35mph.

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Dan Empfield
aka Slowman

It seems to be generally accepted but I don't know why. I personally don't subscribe to it as I don't think we have definitive data on it. We have sites like BRR that show a 28mm rolling faster than a 25mm at the same pressure but that doesn't translate to the real world. I think this confuses many and it leads to a false narrative. Lets assume 80 psi is the break point pressure for the 25mm tire, you wouldn't run the 28mm at 80psi. You would run it at say 75psi. What is the crr at the breakpoint pressure of the 28mm tire vs the 25mm tire at 80psi? This has been discussed several times on here and I forget who it was but someone mentioned that the crr would be roughly the same.

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I agree. And I also believe in between that resin covered wood and Paris Roubaix there is a spectrum. I don't believe you will see a huge difference in RR on a 28 and 25 tire at optimal pressure on many roads used in tri and TT.

It's interesting "oh, the aero penalty is measured and so small it can be ignored". "We didn't measure the RR gain, but trust us, it's worth it"

Measure the whole thing, then we can talk.

Summer projects.....:-)

I wasn't disagreeing with you. When casing tension is normalized, on a roller 23, 25, 28 all seem to roll the same. The higher volume tires seem to lose less energy from rolling over rough roads though. However, this is super specific to your road and tire pressure, which makes it hard to make a nice chart showing this. My point was that its very difficult to visualize this data in a way that allows for easy comparisons.

Also, cornering on 28mm tires feels much better IMO than 25mm tires, which is very important for them.

I have a mad scientist type question... Is it true that rolling resistance generally decreases as tire width increases, assuming we set each tire at its optimal pressure? And this depends on the road surface. But, there must be a point at which rolling resistance starts to increase again as width increases. So, do you think that there is some normal-like curve that illustrates the fastest width tire for a given surface, like this? Or, do you think rolling resistance does decrease indefinitely as width increases? If the former is true, then we will eventually arrive on an ideal tire width for various surface types. Then it is merely a matter of optimizing the wheel for max aero at that optimal width and pressure.

Certainly there is going to be a point where rolling resistance increases with additional width. The biggest toroidal tire that you can fit is ~350mm wide. It would literally be the shape of a donut with a tiny little hub through the middle. I don't see any reason to suggest that such a large amount of flexible casing would produce lower resistance on anything but the harshest of surfaces. Remember on a theoretical perfectly smooth surface the fastest theoretical tire is completely rigid. Of course this provides no grip and isn't a real world case, but it's a good spot to ground your thinking. Everything past that is a balance of absorbing surface imperfections with minimal flexing losses in the casing.

It needs to be tested, but anyone who's ridden a MTB or fat-tire bike on a road can feel the difference in rolling resistance between those tires and any normal road tire. I'm sure the knobs have an impact on that.

PS - Did you make that graph? I'd be curious to see the article it came from if you found it online.

I made it in Excel to illustrate my question. The data are nonsense - just illustrative to fall in the shape of an inverse bell curve.

if you lowered the pressure, going from 25c to 28c, by only 5psi then the 28c would well outperform 25c on a drum roller. it's more like 10 psi or more.

here's why i think teams are moving to 28c with the proviso that some of this is a guess and some is what i've actually heard.

1. handles better, corners better.
2. more comfortable.
3. less chance of puncture.
4. is faster for this reason: the wider tire with lesser pressure, while rolling equally well as or slightly better than the thinner, higher pressured tire, does much better at sucking up bad or irregular patches of asphalt, and the speed delta between 25c and 28c is much bigger over those bad patches, ruts, jumps, curbs, etc.

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Dan Empfield
aka Slowman

years back, when everyone was running 23mm tires, the enve 7.8 front was found to magically become a fast wheel when fitted with a 25mm tire which was considered wide at the time. i think it was Jim@ERO that identified this. so there is certainly precedent for wider tires reducing aero drag with the right rim shape.

as for RR, it was even longer ago determined that for a given casing tension and load, a wider tire has the same contact patch as a narrower one but it is a short, wide contact patch rather than a long narrow one. as well as giving better grip, this rolls better as there is less deformation in the direction of movement.

of course most things improve until they reach a threshold point and then start going the other way. where that point lies is dependant on many things and currently unclear

Thanks for the answer. To close the loop on if wider is at all better on decent roads. It would be really interesting to see the optimal setup for the same model of 25/28/30mm tires on the same wheel compared (combination of rr and aero) on decent road surfaces with pictures of the road surface. I'm very skeptical that 28mm is going to be faster than 25mm, and I assume 30mm will be the slowest.

Then add an accelerometer glued to the seat post also, and we can get data on comfort and hysteresis loss in the rider to some extent. If you need help analyzing the vibration data, I can help as I do some of that at work.




I think this is the crux of the matter, the manufactures claim that wider is faster but refuse to share any data making their claims look suspicious. If they had the data and it was as clear cut as they make it seem, why don't they release it. It would help to convince everyone especially hold outs like me to switch to wider tires/wheels. The fact that they haven't implies: the data isn't as clear cut as they make it seem, they haven't collected any or it's very noisy, or they've tested it and wider isn't faster so it's just marketing speak to convince people to buy new equipment. I hope it's not the last scenario. But with their handling of hookless to help their bottom line, I wouldn't be suprised.

I was using 5 psi delta as an example. Whether it’s 5, 8, 10, or 12 psi delta, the question still remains.

What are teams doing during TT’s? Are they running 25s or 28s? This seems to be a better comparison for tri. I’m not sure the criteria for selecting tire size is the same for a typical road stage (assume no cobbles and relatively smooth surface) vs a TT stage. It seems to me based on pictures I’ve seen that the top guys are running 25mm tires during TT stages but maybe I missed something. Perhaps Marc can chime in here.

I agree with #1 and #2 above. Not sure I understand #3. Could you elaborate?

#4 - so do 28mm tires roll equally as well as 25mm or do the 28mm tires roll faster? Marketing speak says they roll faster but then you just said something different and different from the original post I quoted.

Disclaimer: I run 28mm tires on my road bike on 19mm internal width wheels. I like them and will continue to ride them on my road bike. I run 25mm tires on my tri bike on 23mm internal width rims (Aeolus rsl 75s) as my training setup. I can see/understand the hype with 28mm tires and feel my tri bike setup could really use them for training purposes. What I don’t know is if I go to 28mm tires, am I gaining or giving up something? If so, how much? I don’t care about giving up something for training purposes So 28mm is a no brainer for my next set of tires on my training setup. But for racing purposes and getting every last .1 watts that I can, I’m not sure yet.

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blog

I am going to try and make this happen. I have a trip scheduled and I can easily get 3 identical sets of wheels setup with 25, 28 and 30.

The riders have blacklisted me since i made them do 3 days of 100km/day of CRR testing at pretty hefty pace on crappy roads. I may have to do the tests myself :-)

If I can make it work out, we can align on how to collect the accelerometer data.

If it's at all near San Francisco. I'll be happy to do some of the test haha

Indeed! Faster is Faster, after all. ;-)

It's been a while since I've tried to measure these sorts of things, but something I always thought wasn't discussed much back in the day in terms of wheel/tire stuff was weight distribution front/rear.

"Fastest" just might be rider positioning such that more weight is on the rear wheel and dialed in aerodynamics/rolling resistance on the front wheel. Looking at the recent trends in the industry, though, we might not be able to test this until the pendulum swings the other way.

...me and my wired SRM Pro/PCV will be waiting... ;-)

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Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
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Agreed, the whole thing is extremely complicated, which is why I prefer "real world testing", i.e., seeing what equipment the winners are using.

Another limiting factor to tire size, besides aerodynamics, is probably the mass of the tire. You can make the carcass only so thin, so as it's size increases, so does it's mass - rotating mass - which is not good.

I have owned at least 3 possibly 4 Zipp Disks over the years and still own a 900 now the main attraction for me was allways the ability to swap out the axle and use for either TT or Track.
The one I own now is tubular and doubles as my Track Disk and Spare wheel if required for TTs as I use a Tubeless ready disk for TTs these days with a Latex tube.
I’m considering replacing the 900 with a Super 9 Clincher that could also be used for TTs and Track.
As I’m never going to use hookless at low PSI on the track and I’m not likely to use hookless on the road either as I don’t really want to have to consult some sort of safety spreadsheet every time I pump up my tyres I will definitely be passing on the latest Zipp Disk.

Your spreadsheet consists of one cell and that cell contains the number 72.5. If that’s too much to remember then yes, you should not have a product like this.

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Dan Empfield
aka Slowman

I’m sure you found your attempt to belittle amusing but there is far more to it than just tyre pressure!
Tyres that supposedly worked 12 months ago on hookless rims now don’t or do with some internal widths but not others. I cannot just walk into a shop and buy a tyre and throw it on the rim like I can with the wheels I own now I have to consult the wheel manufacturer data and the tyre manufacturer data and adjust pressure not for road conditions but to stop the tyre unseating. If I fix a flat with Co2 out on the road how do I know I haven’t exceeded the safe limit for pressure?
It’s almost a bike tyre version of the Manchester Triage System when something goes wrong the system is amended.
If the pro Peleton are having problems with their average weight being less than <70kg and their bikes set up by professional mechanics perhaps hookless rims are not a very good idea for the mass market?
Or maybe they are just not there yet?
Either way I think I will pass for now as I’m not currently being forced by the industry to buy them.

A CO2 cartridge is ~800psi and ~16g and 0.16L. The volume of a 700x28 tire is roughly 3.14*(2.8/2)^2*(67.8*3.14)=1,310cc=1.31L, actually a bit more because of the rim beyond a circular tube. Remembering high school chem PV=nRT, nRT is all going to be equal to we get PcVc=PtVt and know 3 of the 4. -> 800*0.16L/(1.31+0.16)=87psi. .

The margins of error on inflating a tire a skewed to one side -- there's lots of ways to get less than the theoretical total amount of air into the tire, the only way to get more is if the CO2 factory inflated to a MUCH higher pressure. Considering the significant variation in floor pump gauges and the physical limitations of CO2 inflation, I'd say that inflating with CO2 is actually a safer bet than inflating with a floor pump.

(attn nerds: I know the ideal gas law is starting to break down at these pressures, but pvnrt is going to overestimate the pressure in the tire when going from a small volume to a big volume as the intermolecular forces become less)

if you don't want to buy the wheels don't buy the wheels. the number of companies making hookless road rims is still in the vast minority. just, based on my experience the issue you describe isn't an issue. i've been riding these wheel and tire systems for 4 years, many different combos, and i haven't faced any issues you describe. there isn't anything anybody really describes here that we didn't face with road tubeless.

in the very beginning of this i established 3 rules for myself: 1) i will not ride this kind of system with any tire narrower than 28c; 2) i will maintain a delta between inner bead width and nominal tire size of between 5mm and 7mm; 3) i will stick to tire and wheel brands i trust.

now, in point of fact, these aren't my private rules i've established for hookless systems; they're for all road tubeless systems i ride, hooked or hookless. so for me no problem. in the beginning of all of this people complained that hookless are not safely usable with 25c tires. fine (i said), i'm not inconvenienced, i only run 28c and up. "but then you can't run them on the fastest tire width!" to which i said, "let's see if 25c remains the chosen tire width." so i'm happy as a clam because the world has turned toward my preferences, techwise.

fortunately for you, you have plenty of hooked rim options. but you are still the beneficiary of hookless i think, because certain tire brands that made beads too stretchable for hookless are having to pay a lot of attention to their beads, and that makes their tires better for your use (their beads too stretchable for safe use on hooked rims as well).

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Dan Empfield
aka Slowman