You missed this??

https://forum.slowtwitch.com/.../?page=unread#unread

Jeroen

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Owner at TRIPRO, The Netherlands

Yes. Sorry. Scanned it now.

Is the answer that all evidence behind wider rims is anecdotal?

There's no good data showing that if you keep casing tension constant between wider/narrower rim/tires that wider rims/tires are actually faster. Barring super bad roads.

If anything wider rim means you need to use a wider tire. Which then causes more drag, even in the rear (just reduced).

wider tire, lower pressure, less contact resistance? so faster...
of course, the tire needs to be a good fit onto the wide rim...so a wide tire smashed on a tiny rim, will always be bad for airflow?
that is what i have heard?

I think it is the other way around. Wider tire means one should mount it on a wider rim for acceptable aerodynamics. In addition, with wider tire the rim should become deeper in order to realize a reasonable aspect ratio. Which in turn however, increases the cross wind sensitivity.

On wide hooked clincher rims one can (safely) mount relatively narrow tires. At least in our velodrome tests such setups often turned out fastest.

Think this is wrong.
The contact area only reduces if tire pressure stays the same when going to wider tire.
But most peaple run lower pressure with wider tires. So the contact aera will be similar.

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Full-time Engineer / Part-time Pro Triathlete
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you are correct, the contact area increases but resistance only drops if pressure stays the same...

The 23mm wide internal width wheel he's looking at means that he is forced to run wider tires. You can't fit a 23mm tire on there safely and maybe not even a 25mm. So he has to run a 28mm which is less aero. Here the wheel manufactures are forcing users to run wider tires. Especially as many wheels are hookless meaning heavier riders say 180 lbs can't run a 23mm as it would require pressures above the safe ~75 psi limit.

I.e. do not buy a hookless rim for fast riding on roads, one is in many ways too much restricted.

4 front page articles, endless threads ....summarized in one sentence

^^^^Bingo! Agreed.

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Kiwami Racing Team

Dan is awesome and super smart, and as the founder he should have an outsized influence on the discussion, but he's almost the only one promoting hookless as a good product for road cycling.

the balance between showcasing for your sponsors, showing the future potential/trends and giving the tangible pros and cons for the consumer, the ones reading your review and considering a purchase today, is a delicate balance.

Maybe in the absence of data, there should be more emphasis on YMMV

And another from one of the home page articles with Dan & Josh:

This is consistent with so many other experts that test stuff. Because of the limitations, hookless systems are not fast. They might be as fast on bad road surfaces as hooked, but no faster. And hooked would be faster on better road surfaces. Further, hookless seems to introduce a significant blowout risk from user error.

Unlike other advances, it does not seem like hookless will get faster or safer with more R&D & refinement; it seems to be an inherently flawed design.

But I bet the margins are better...

I think that is the only benefit...

But are those savings passed on to the consumer? I don't really see a significant decrease in hooked vs. hookless.

Another recent "advance" in road cycling that's a function of marketing departments is continuously wider wheels to make people want to buy new equipment. They are great for gravel but not any faster or more comfortable for road, if you're running the right pressures.

I do not believe this is accurate, based on rolling resistance and all the tests that experts in the other threads posted. And as another said, the comfort difference is not subtle.

As said above if you don't make pressure adjustments (lower the correct amount) for wider tires, then yes wider will be faster and more comfortable. But there hasn't been any data showing that when you do, wider tires are faster on decent surfaces. If you know of any please share it with me.

The same applies to comfort, and that's harder to measure especially with how powerful the placebo effect is.

I think you are mixing a lot of things together and arguing yourself into an impossible corner. I recommend study through this thread. https://forum.slowtwitch.com/...c_P8115313/#p8115313

Several folks who test with top tier pros and pro teams posted. They helped teams find the optimal systems (wheel, tire & size, and pressure). Many are running wider tires and 28s are common. And as I said, the comfort difference is definitely not subtle. I was not a believer, until I experienced the difference and bought a new bike because of it. As did a friend of mine.

Sounds like you are just trying to self-justify sticking with your older equipment. That’s ok. I’m sticking with my 25mm/23mm rim brake setup on my TT bike, because I don’t want to hassle with the change.

Thanks for the link. However I've seen that thread and no where do they ever provide data regarding the speed/comfort of wider tires once things are normalized for equivalent casing tension.

If anything Marcag doing testing on rough roads and still finding that high pressures are needed for optimal rolling resistance on 28c tires (80 psi for a 59kg rider on decent roads) flies in the face the new marketing telling riders to run low pressures with 28c tires, making the other marketing claims even more questionable.

In the case of the 59kg rider, he mentioned that she was running a 25mm but had to switch to 28mm to remain in the safe pressure ranges for hookless. Nothing about if 28mm is faster than 25mm.

I'm not quite following. Yes, a tire of any width should have a pressure consistent with that width, the road surface, and system weight. Don't think that's in dispute.

Edit: Ah, I think I get the point now....that wider tires are "faster" on smooth rollers at inappropriately high pressures. Gotcha.



It *is* hard to measure! But often we have bias towards things that are easy to measure. (Cue my frustrations with engineering managment trends where managers fixate on narrow metrics at the cost of the big picture) And just because the placebo effect exists does not mean a real effect doesn't exist to maybe find.

Anecdotally speaking, of all the people I know who've gone from 23m to 28mm road bike tires, not one has gone back the other way. It's one hell of a mass delusion if it's a delusion. Most recently a 55 y.o. grizzled veteran masters racer I know who used to give me side eye about my 30mm road tires. He was recently forced to replace his ~2015 Tarmac with a 2024 Tarmac. To say he's in love with it, and the tires it came with (28mm Specialized 2Bliss), is an understatement.

I think you must be in the 11% in the poll to the right. Optimize the #'s we can optimize at all costs. Everything else is namby-pampy stuff. I'm in the 68% on this one, despite being somewhat of an # optimizing zealot in most cycling contexts.

I think we should clarify the above statement is only true when doing testing on rollers.

It’s a different conversation (and this is the problem with sites like BRR) when you take it outside and do real world crr testing.

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blog

Thank you. That's a better of putting it. Reframed more clearly, I believe that lowest achievable rolling resistance for a given tire model on decent roads is not lower for a wider tire than a narrower tire. All the data I've seen has not put any effort into finding the optimal pressures for the two widths and instead tests them at the same pressure.

I definitely care about comfort even if it's harder to measure as discomfort leads to fatigue which leads to lower performance from the rider. I just don't agree that wider tires are more comfortable on non-bad surfaces.

In the case of comfort, if we should assume that on good roads different tires show minimal differences in comfort due and we should focus on rougher roads. On these rougher roads I believe that a faster (lower rolling resistance we will disregard aero here) tire when tested with a rider on the intended surface should be more comfortable. Due to reduced transfered vibrations and therefore hysteresis losses in the soft deformable body that is the rider.

I recently had to switch from a 23 to 28mm gp5000 in the rear due to the shop now having a 23 or 25mm in stock after a bad flat, and I didn't notice any differnece in comfort despite running much lower pressures on the 28mm. However I am also riding on very nice roads, if one on riding on poor quality (cracks and potholes) or chipseal there is likely to be a difference.

Yes I agree I should have specified that.

I’ve come to the following hypothesis regarding hookless for road/tri:

Hookless w/ 28 mm tires gets you 90-98% of the performance (strictly talking aero and rolling resistance) of hooked w/ 23 or 25 mm tires depending on the wheels. Mfg’s are depending on the comfort aspect to the close the rest of gap and potentially even exceed it. We just haven’t found a way to objectively measure comfort or utilize an existing test/measurement (eg: lactate, hr drift, etc) and make it part of the overall equation.

I’m not sure if we will ever get the last part but time will tell.

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blog

That's fair. I was OK on 23mm in coastal SoCal. Now I'm in the Sierra Nevada foothills. Expansion joints in every direction. 23mm is just brutal.

I agree that there's no significant speed advantage in Crr or Cd with hookless/wider/tubeless.

I'm still a huge believer in the latter two for reasons other than measurable speed. Rather I think their miniscule losses are worth the benefits. And I'm the guy with aero calf sleeves, etc.

My jury is out on hookless for road. It's in for gravel and MTB. No-brainers there. There is some nonsensical stuff written about the advantages. Enve's road hookless evangelical page is....puzzling....to me.

With a decent dataset from a accelerometer glued to the seat post and analysis of the power spectral density between two tires will tell us most of what we want to know in the sense of is tire A or B more comfortable. How that comfort turns into a performance benefit is more nebulous.

This also isn't true. You can drop the pressure some, and still have lower RR with the bigger tire (to a point). A wider/shorter contact patch has lower hysteresis losses than a narrower/longer patch.

We did capture the vibration data. We also asked the riders to give their subjective scores of comfort and we correlated with the vibration data.

As for "benefit", I guess we can use the philosophy of something is worth what someone is willing to pay for it. We asked the riders if when comparing the pressure before and after the 5bar breakpoint if they would "pay" say 4watts for that, the answer was no.....2....not even....

I think this is a strawman logical fallacy. Or you are not seeing the forest through the trees. It looks like you are setting up casing tension as the ultimate measure. But it is truly irrelevant. Those experts are finding the fastest system, and they do not care about casing tension. They are using their testing protocols to determine the fastest combination of wheel, tire, tire width, and tire pressure for their riders. The end result is that many of them are on wider tires, some as wide as 28mm. And they are on lower pressure too, but not as low as the 5 bar hookless max.
I'm not sure I need anyone to quantify comfort. Though, marcag did make an effort to capture that from his riders.

My personal experience is that I did a fondo event on a demo bike. I had no agenda and no plan to buy a new bike - I loved my 7 year old bike. I did a test ride on chipseal pavement and was blown away by how much smoother it was. My friend at the event had the exact same reaction on his demo bike. It was kinda unbelievable how much better the wider tubeless felt. Both of us were running 25mm on our personal bikes, but at 80 PSI. We talked to several of the pros in the event about bike comfort, wide tires, pressure, etc. By the end of the event, I decided to buy one of those bikes, almost on the spot. It is radically more comfortable than my former bike.

It is my road bike, and I do not ride it for maximum speed, so that was not part of my decision. But the consensus opinion from reading here, by other experts, and a few former pros, is that you do not give up much speed, if any, on wide tires at 60-ish PSI. And the comfort factor is a huge bonus.

I think this may be an inadvertent case of selection bias. I don't know many people riding 23mm, 25mm seems to be the standard for narrow tires. (on a tangent the ideal road racing tire on modern rims is probably 28-30, the draft in a race changes a lot of the numbers from tt/tri world)

Regardless, for the switching anecdote I can think of three big groups - 1) Got new wheels and the optimal (or at least very close to optimal) tire size is ~28 because of the rim design. No reason to switch to 23's. 2) Kept old wheels and didn't change tire size, not part of the given sample. 3) Kept old wheels and moved to 28's. I don't doubt that the preponderance of people in this specific group also kept them, but they were either speed or comfort driven - comfort makes sense, but if speed driven surely they saw some benefit to the switch.

The point I'm getting at is that someone wouldn't switch to 28's without a reason, and that reason would need to be found false for them to switch back. Not just a little false, but false enough for them to admit to themselves and their riding buddies that they got it wrong.

Disregarding hookless for the moment. Have you found that the lowest achievable losses on a 28mm tire is better 25 or 23mm (assuming same wheel).