Tom A. wrote:
Hoo boy...I go out for a ride on a Sunday morning and all confusion breaks out... ;-)Sorry. My fault :-)
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Re: New Zipp 858 NSW and 808 [Tom A.]
[ In reply to ]
Sorry. My fault :-)
Re: New Zipp 858 NSW and 808 [marcag]
[ In reply to ]
marcag wrote:
Tom A. wrote:
Hmmm...maybe I'm missing something...the y-axis is labeled as Crr, and the values are of a range I'd expect for the data. Please educate me on what's incorrect. Genuinely curious.
I had to look twice, but notice the y axis. Notice .002, .004, .006 then .007, .009....
Aaah...interesting...I wonder if that's ever been pointed out to Josh.
http://bikeblather.blogspot.com/
Re: New Zipp 858 NSW and 808 [marcag]
[ In reply to ]
marcag wrote:
Tom A. wrote:
Hoo boy...I go out for a ride on a Sunday morning and all confusion breaks out... ;-)
Sorry. My fault :-)
Nope...you weren't the only one confused by those plots and their presentation. Not our fault...
http://bikeblather.blogspot.com/
Re: New Zipp 858 NSW and 808 [Tom A.]
[ In reply to ]
do you think there is the possibility of a relatively common range of road surfaces where this system will not be optimal due to it's inability to support higher tire pressure and no aero advantage due to it's width ?
Re: New Zipp 858 NSW and 808 [marcag]
[ In reply to ]
marcag wrote:
do you think there is the possibility of a relatively common range of road surfaces where this system will not be optimal due to it's inability to support higher tire pressure and no aero advantage due to it's width ?
To be honest...I really don't know what to make of any of it, one way or the other ¯\_(ツ)_/¯
http://bikeblather.blogspot.com/
Re: New Zipp 858 NSW and 808 [Slowman]
[ In reply to ]
Slowman wrote:
but what i will tell you is this: when i slap a set of calipers on all these new hookless tires and rims, they all obey the rule of 105 with 28mm tires on. i know of almost no hookless road wheels with inner bead widths of less than 22.5mm. these wide inner beads push the width of the wheel, and i haven't measured any hookless rims that are less than 30mm in width on the outside. the 28mm tire is routinely 29mm inflated. so, you aren't riding a lollipop.going back to simple matters for a moment, can i get clarification on the external width please.
the cyclingtips article says "23mm internal and 27mm external rim widths" and i've seen those same specs elsewhere on both these wheels and other recent model zipps. zipp don't seem to give external width on their website and i don't think i've seen external width specs anywhere else.
30mm is still marginal on rule of 105 for a tyre likely to measure 29mm+ inflated but its a damn sight better than 27mm
Re: New Zipp 858 NSW and 808 [Ohio_Roadie]
[ In reply to ]
I agree with the general sentiment that the charts are a bit inscrutable.
Like, what is "delta power"? When there's no apparent zero-delta data covering the entire x-axis, or reference to what "zero" refers to, what is it a "delta" from? Is the whole thing actually just an absolute chart where the y-axis has a constant bias, or is it referenced to some other data set?
Like, what is "delta power"? When there's no apparent zero-delta data covering the entire x-axis, or reference to what "zero" refers to, what is it a "delta" from? Is the whole thing actually just an absolute chart where the y-axis has a constant bias, or is it referenced to some other data set?
Re: New Zipp 858 NSW and 808 [Slowman]
[ In reply to ]
Slowman wrote:
Cajer wrote:
Slowman wrote:
the data, or the compilation and results from the data, from zipp on their new wheels is up on our front page. tom, you wrote in a FB comment below that article, "Can you ask Zipp for the plots in raw power? These delta plots are a regular "dogs breakfast" in trying to understand what they're trying to say, and how things agree, or don't agree, with other data...and seems a bit "obfuscation-y". Some details on the rolling road setup would be nice. If you're wanting to call this "science", then details of the test methods should be revealed. No way to put the results in context without that."
i assume you're talking about the Crr data. i'll ask zipp about that. there is some additional color i can give you, tho it's not specifically what you're asking. there was 1 rider on the rolling road for all the runs. the weight was 85 kilos total, with the bike. i believe the entire suite of runs was 96. there were 4 pressures x 3 tire sizes for each wheel. the 808 firecrest and 858 NSW were tested. so, that's 24 total discrete plot points. that's how i can up with (in the article) 4 runs per discrete instance. what i don't know is what was done with those 4 points. average the 4? throw out the 2 on either side and average the other 2?
i disagree with you that the way zipp presented this increases obfuscation. the way they presented the data was designed to do exactly the opposite and i think they achieved that. the data they provided is designed to help their audience understand what these new wheels give you over the old wheels.
if i can spitball here a little: they aren't claiming science in this sense: they're not claiming that their charts, as presented, are ready for publication and will withstand all reasonable scrutiny. they're claiming science in this sense: science is what guided them, internally, on the choices they made. they're sharing their internal results with their readers; they're not presenting a paper to nature magazine.
but i agree with you that we can't just stop here and call it good. i have some of the same questions you do. i think we all know there is value to drum testing, and there are limitations to drum testing. but up 'til now drum testing has been the easiest, cheapest way to test tires, and so drum testing has been gospel. rider-aboard testing seems a step forward, but it's so infrequently used that i don't know that we all know what its limitations might be.
Thanks for posting the write up however. It still leaves allot of questions unanswered regarding the rolling road itself. There is no information on either what surface they are trying to simulate with the rolling road: rough/smooth asphalt?, dirt/gravel? (for the 303 relaunch and their TSE numbers they were doing dirt roads to get the large efficiency gains). I am very curious what the surfaces look like and especially what the interface between the segments look like. Do they create smooth transitions or is there some sort of bump every time?
To clarify this, I would really like to see a PSD plot of the rolling road vs the road surfaces they are trying to simulate and pictures of the roads they are trying to simulate themselves. Additionally with a PSD we would be able to quantify the comfort increases, and reduction in rolling vibrational losses that we see to further provide color to their TSE story.
I have access to some high quality accelerometers. I might actually do that experiment myself, setting my current tires at varying pressures and looking at the change in the PSDs, but controlling the speed and which part of pavement Im riding over exactly will introduce some noise the measurements as I would want to ride over the same segment 10s of times to get better data.
feel fry to hypergeek but please remember and respect your audience (and offer succinct background when appropriate). i assume you refer to power spectral density and i can see how this might be measured either with an accelerometer or a photometer. if zipp didn't do this at the point of testing they don't have that data for you.
perhaps if you find yourself in the proximity of indianapolis i might try to make a match between zipp and you for the purpose of seeing what their rolling road surface really is.
what they say that surface is is "standard" road, analogous to the eagle creek field loop they use. i could imagine, tho, that the entire contraption might have some give to it. imagine a treadmill that has x amount of bounce built in, but y amount of bounce simply due to the vibration of the entire unit. any additional bounce or vibration that unweights the rider might make the rolling road's results mimic a slightly rougher road than the belt surface itself. i'm wildly speculating here. i don't know.
i'm *provisionally convinced* by zipp's data, tho that phrase is kind of an oxymoron. i find the data compelling. just, my wild speculation would help answer the one question i have, which is, why is the ideal tire pressure so low in the 858 NSW graph? i'm provisionally convinced that the new wheel is fast, and faster than the old, and with the 28mm tire. i'm not yet convinced i'd run it at 50psi or lower.
I would love it if you could try to make a match between Zipp and I! I would be happy to fly out to Indianapolis if that happens! I am also very curious how they're testing/modeling their wheels, as they are showing large rolling resistance
Is hypergeek a Zipp representative here on slowtwitch? Yes I am referring to power spectral density measurements. I imagine they have them as it's more or less required to compare vibrations of two bodies especially to validate that one test is simulating real world vibrations. That being said I can understand why they created the rolling road, in order to shorten the testing loop on rolling resistance/width/pressure changes. But echoing what TomA has said, I don't believe they can achieve 1 or even 2 watt resolution/repeatability without ten or hundreds of runs due to the fact that there is a floppy human on top plus there's still steering involved.
Also to provide another point of info, on Bigham's hour record attempt they lowered the pressure from the traditional ~200 psi to ~130 psi and round rolling resistance reductions even on the very smooth track surface even with centripetal forces providing additional load on the tires. So I am starting to believe that quite low pressures are the way to go on road.
Re: New Zipp 858 NSW and 808 [Cajer]
[ In reply to ]
Cajer wrote:
Also to provide another point of info, on Bigham's hour record attempt they lowered the pressure from the traditional ~200 psi to ~130 psi and round rolling resistance reductions even on the very smooth track surface even with centripetal forces providing additional load on the tires. So I am starting to believe that quite low pressures are the way to go on road.Interesting...and it matches some data shared with me a long time ago about some informal tests done at the Carson, CA velodrome. Do you happen to know what the track surface is at the velodrome Bigham used? The speculation at the time was that if tire pressures are too high (i.e. 200 psi), then the compliance of the track itself starts coming into play.
I did some tests around the local high school running track one time, which has a "compliant surface"...it had a quite dramatic effect on the measured Crr. Additionally, I know that Josh has seen in his Silca testing differences in Crr for freshly laid asphalt vs. the same surface that has "cured" for a few months. In other words, surface compliance matters ;-)
Of course, surface compliance is basically why MTB tests usually result in: "the fastest pressure is the lowest you can run without pinch flatting" :-)
http://bikeblather.blogspot.com/
Re: New Zipp 858 NSW and 808 [pk1]
[ In reply to ]
pk1 wrote:
Slowman wrote:
but what i will tell you is this: when i slap a set of calipers on all these new hookless tires and rims, they all obey the rule of 105 with 28mm tires on. i know of almost no hookless road wheels with inner bead widths of less than 22.5mm. these wide inner beads push the width of the wheel, and i haven't measured any hookless rims that are less than 30mm in width on the outside. the 28mm tire is routinely 29mm inflated. so, you aren't riding a lollipop.going back to simple matters for a moment, can i get clarification on the external width please.
the cyclingtips article says "23mm internal and 27mm external rim widths" and i've seen those same specs elsewhere on both these wheels and other recent model zipps. zipp don't seem to give external width on their website and i don't think i've seen external width specs anywhere else.
30mm is still marginal on rule of 105 for a tyre likely to measure 29mm+ inflated but its a damn sight better than 27mm
you're right. i misreported. at least on the 808 firecrest. i made an assumption based on everyone's wider internals, and failed to remember the big differences between the 404 and the 353 NSW. here are some examples:
above are a couple of CADEX wheels i have on road bikes of mine right now.
above is the ENVE 6.7
even the newer wheels that aren't hookless are fat on the outer width. this is the new bontrager 75 and i don't even know that it's 32+mm. it's lenticular (to my caliper) and my caliper isn't long enough to (necessarily) catch the widest part of the rim.
here above is the 353 NSW. (i love this wheel.) this is probably the closest analog to the 858 NSW, in terms of construction, but i don't have that 858 NSW and so didn't have the chance to measure it.
i believe i've met my own site's max for number of attachments, so i'll post about the 404 and the 808 firecrest in the next post.
Dan Empfield
aka Slowman
Re: New Zipp 858 NSW and 808 [pk1]
[ In reply to ]
following on my post just above, here's the 404 firecrest released maybe 2 years ago? i think?
this is kind of an outlier on wheels like this, with fat inner bead widths and especially (but not exclusively) hookless. this should've given me a clue about the 808 firecrest just launched.
here's the 808 firecrest. i suspect - but don't know for sure, because i don't have it - the 858 NSW is fatter. but i don't know. cyclingtips was right, at least about the 808.
Dan Empfield
aka Slowman
this is kind of an outlier on wheels like this, with fat inner bead widths and especially (but not exclusively) hookless. this should've given me a clue about the 808 firecrest just launched.
here's the 808 firecrest. i suspect - but don't know for sure, because i don't have it - the 858 NSW is fatter. but i don't know. cyclingtips was right, at least about the 808.
Dan Empfield
aka Slowman
Re: New Zipp 858 NSW and 808 [HTupolev]
[ In reply to ]
HTupolev wrote:
I agree with the general sentiment that the charts are a bit inscrutable. Like, what is "delta power"? When there's no apparent zero-delta data covering the entire x-axis, or reference to what "zero" refers to, what is it a "delta" from? Is the whole thing actually just an absolute chart where the y-axis has a constant bias, or is it referenced to some other data set?
delta force, delta drag, delta power. i don't know why you don't know what this means, unless i didn't explain it well enough in the article (which might be the case). it's the difference between the performance of prior wheels zipp made and these new wheels they replace. as i understand it, you're asking for the underlying data from the prior wheels, that are a few years old. maybe that's available, when those wheels were launched. but that's another set of data; another topic; of scant relevance to what zipp is trying to show here.
Dan Empfield
aka Slowman
Re: New Zipp 858 NSW and 808 [Tom A.]
[ In reply to ]
Tom A. wrote:
marcag wrote:
Tom A. wrote:
Hoo boy...I go out for a ride on a Sunday morning and all confusion breaks out... ;-)
Sorry. My fault :-)
Nope...you weren't the only one confused by those plots and their presentation. Not our fault...
what's confusing you? perhaps i can help. i have questions, for sure. but none of these charts have me confused.
Dan Empfield
aka Slowman
Re: New Zipp 858 NSW and 808 [marcag]
[ In reply to ]
marcag wrote:
On the aero side of things, I found what you wrote interesting
"However, as I read the notes on the test the one notable item is that 25mm tires were used throughout in the wind tunnel tests. (Not in rolling resistance, but wind tunnel.) I don’t have any wind data using a 28mm tire on either of these new wheels. While it would have made some sense to test this wheel with a 28mm tire, Zipp chose the 25mm size – in fact they used Zipp Tangente tires for their aero testing – because of all the historical data they have in the tunnel that used this tire."
I had a flash back to this
joshatsilca wrote:
I can't share the data, but I attended a tunnel test at Silverstone last week with one of our world tour teams and won myself a bottle of wine in a bet about this exact topic. The wheel sponsor delivered a new wheel designed around a 28mm tire that could achieve ~102% of tire width (tubeless setup), the wheel they had previously was only at 99% with a 26mm tubeless tire and the new setup with 28 was indeed faster.. everybody was thrilled about this new faster 28mm setup, so I bet them that the new wheel would be even faster still with the 26mm tire.. and of course, it was.
I wonder if we have hit the peak of aero on wheels
of all the posts i awoke to this morning, yours is the most interesting. here is what i took josh's anecdote to mean (when i first read it, and now). josh was giving an example of what you can predict when the rule of 105 is disobeyed. in the case of the wheel designed around a 28mm tire, what josh was saying (i think) is that this wheel disobeyed the rule of 105 with a 28mm tire on it, and if you replace it with a 25mm tire the rule is obeyed so the wheel will test (at least marginally) better.
that said, there's a lot about this new wheel (whatever it is) that may still make the new wheel faster, and if you look at zipp's data here on Crr you can see why. just above i've posted some pics of wheel widths, and what is typical among these new wheels - hooked and hookless - are external rim widths of 30.5mm to 32mm (the 808 firecrest notwithstanding). this makes these wheels good candidates for rule of 105 obedience with 28mm tires installed (which typically measure about 29mm inflated on these wheels).
as to your question of whether the wheels are capable of improvement, sure. but that's the wrong question. the game changer over the last 5 or so years is disc brakes. when you decouple rim braking from the whole system you get to make changes to the whole system not possible. the flashiest examples, maybe, are the bikes with really wide stays and blades that seek to overcome interference drag. the CADEX, the KU, the Shiv Disc. once you look at systems then you can imagine wheel design that works best in a system like that which, i've always felt, calls for (among other things) narrow hub flanges. which is exactlyl what i had steve hed build for me back in the mid 1990s, when i had kinesis build me a fork with wider blades. what we did at QR back then didn't come close to the designs i name above, but what we did worked pretty well, i think, based on what we had to work with.
what will change is the approach. we're making motorcycles now. motorcycles without engines. that requires new thinking. the whole idea of taking a wheel to the wind tunnel will vanish.
Dan Empfield
aka Slowman
Re: New Zipp 858 NSW and 808 [Tom A.]
[ In reply to ]
Tom A. wrote:
Cajer wrote:
Also to provide another point of info, on Bigham's hour record attempt they lowered the pressure from the traditional ~200 psi to ~130 psi and round rolling resistance reductions even on the very smooth track surface even with centripetal forces providing additional load on the tires. So I am starting to believe that quite low pressures are the way to go on road.
Interesting...and it matches some data shared with me a long time ago about some informal tests done at the Carson, CA velodrome. Do you happen to know what the track surface is at the velodrome Bigham used? The speculation at the time was that if tire pressures are too high (i.e. 200 psi), then the compliance of the track itself starts coming into play.
I did some tests around the local high school running track one time, which has a "compliant surface"...it had a quite dramatic effect on the measured Crr. Additionally, I know that Josh has seen in his Silca testing differences in Crr for freshly laid asphalt vs. the same surface that has "cured" for a few months. In other words, surface compliance matters ;-)
Of course, surface compliance is basically why MTB tests usually result in: "the fastest pressure is the lowest you can run without pinch flatting" :-)
It was a wooden track. He did testing at Grenchen Switzerland. I'm not familiar with the track, so I can't say if it's more or less compliant than other wooden tracks.
I totally agree that a significantly softer surface would create higher rolling resistance. It's basic tribology. With this recent realization. I'm much more willing to accept lower pressures being better. But I'm a bit less convinced on wider tires at same casing tension/equivalent pressure without seeing the rolling road setup. However the easy part is knowing lower is better. The hard part is figuring out how much lower.
I'm also super curious what layup tricks Zipp is playing to try and get the claimed very large hysteresis gains between the 404/454.
Re: New Zipp 858 NSW and 808 [Slowman]
[ In reply to ]
Slowman wrote:
marcag wrote:
On the aero side of things, I found what you wrote interesting
"However, as I read the notes on the test the one notable item is that 25mm tires were used throughout in the wind tunnel tests. (Not in rolling resistance, but wind tunnel.) I don’t have any wind data using a 28mm tire on either of these new wheels. While it would have made some sense to test this wheel with a 28mm tire, Zipp chose the 25mm size – in fact they used Zipp Tangente tires for their aero testing – because of all the historical data they have in the tunnel that used this tire."
I had a flash back to this
joshatsilca wrote:
I can't share the data, but I attended a tunnel test at Silverstone last week with one of our world tour teams and won myself a bottle of wine in a bet about this exact topic. The wheel sponsor delivered a new wheel designed around a 28mm tire that could achieve ~102% of tire width (tubeless setup), the wheel they had previously was only at 99% with a 26mm tubeless tire and the new setup with 28 was indeed faster.. everybody was thrilled about this new faster 28mm setup, so I bet them that the new wheel would be even faster still with the 26mm tire.. and of course, it was.
I wonder if we have hit the peak of aero on wheels
of all the posts i awoke to this morning, yours is the most interesting. here is what i took josh's anecdote to mean (when i first read it, and now). josh was giving an example of what you can predict when the rule of 105 is disobeyed. in the case of the wheel designed around a 28mm tire, what josh was saying (i think) is that this wheel disobeyed the rule of 105 with a 28mm tire on it, and if you replace it with a 25mm tire the rule is obeyed so the wheel will test (at least marginally) better.
that said, there's a lot about this new wheel (whatever it is) that may still make the new wheel faster, and if you look at zipp's data here on Crr you can see why. just above i've posted some pics of wheel widths, and what is typical among these new wheels - hooked and hookless - are external rim widths of 30.5mm to 32mm (the 808 firecrest notwithstanding). this makes these wheels good candidates for rule of 105 obedience with 28mm tires installed (which typically measure about 29mm inflated on these wheels).
as to your question of whether the wheels are capable of improvement, sure. but that's the wrong question. the game changer over the last 5 or so years is disc brakes. when you decouple rim braking from the whole system you get to make changes to the whole system not possible. the flashiest examples, maybe, are the bikes with really wide stays and blades that seek to overcome interference drag. the CADEX, the KU, the Shiv Disc. once you look at systems then you can imagine wheel design that works best in a system like that which, i've always felt, calls for (among other things) narrow hub flanges. which is exactlyl what i had steve hed build for me back in the mid 1990s, when i had kinesis build me a fork with wider blades. what we did at QR back then didn't come close to the designs i name above, but what we did worked pretty well, i think, based on what we had to work with.
what will change is the approach. we're making motorcycles now. motorcycles without engines. that requires new thinking. the whole idea of taking a wheel to the wind tunnel will vanish.
You (and I) wondered why they didn't provide 28mm aero data. I wondered if the reason is 28 is less aero than 25 or 26 as Josh found.
I have no doubt there is still room for system improvement. I do believe in opportunity with fork width and fork/wheel interaction.
I also remember a podcast with one of the Look engineers who said wide was an opportunity for tri spokes to make a comeback. That may be interesting
I am chomping at the bit to get a new bike but have to admit I would not know what to but if I had to tomorrow morning. At this point I'd probably go Hed-hooked.
I just need to find a person that has these wheels. I have all I need to prove/disprove their performance on road. I just don't have the wheels and I'm not paying that price to find out :-)
Re: New Zipp 858 NSW and 808 [marcag]
[ In reply to ]
marcag wrote:
Slowman wrote:
marcag wrote:
On the aero side of things, I found what you wrote interesting
"However, as I read the notes on the test the one notable item is that 25mm tires were used throughout in the wind tunnel tests. (Not in rolling resistance, but wind tunnel.) I don’t have any wind data using a 28mm tire on either of these new wheels. While it would have made some sense to test this wheel with a 28mm tire, Zipp chose the 25mm size – in fact they used Zipp Tangente tires for their aero testing – because of all the historical data they have in the tunnel that used this tire."
I had a flash back to this
joshatsilca wrote:
I can't share the data, but I attended a tunnel test at Silverstone last week with one of our world tour teams and won myself a bottle of wine in a bet about this exact topic. The wheel sponsor delivered a new wheel designed around a 28mm tire that could achieve ~102% of tire width (tubeless setup), the wheel they had previously was only at 99% with a 26mm tubeless tire and the new setup with 28 was indeed faster.. everybody was thrilled about this new faster 28mm setup, so I bet them that the new wheel would be even faster still with the 26mm tire.. and of course, it was.
I wonder if we have hit the peak of aero on wheels
of all the posts i awoke to this morning, yours is the most interesting. here is what i took josh's anecdote to mean (when i first read it, and now). josh was giving an example of what you can predict when the rule of 105 is disobeyed. in the case of the wheel designed around a 28mm tire, what josh was saying (i think) is that this wheel disobeyed the rule of 105 with a 28mm tire on it, and if you replace it with a 25mm tire the rule is obeyed so the wheel will test (at least marginally) better.
that said, there's a lot about this new wheel (whatever it is) that may still make the new wheel faster, and if you look at zipp's data here on Crr you can see why. just above i've posted some pics of wheel widths, and what is typical among these new wheels - hooked and hookless - are external rim widths of 30.5mm to 32mm (the 808 firecrest notwithstanding). this makes these wheels good candidates for rule of 105 obedience with 28mm tires installed (which typically measure about 29mm inflated on these wheels).
as to your question of whether the wheels are capable of improvement, sure. but that's the wrong question. the game changer over the last 5 or so years is disc brakes. when you decouple rim braking from the whole system you get to make changes to the whole system not possible. the flashiest examples, maybe, are the bikes with really wide stays and blades that seek to overcome interference drag. the CADEX, the KU, the Shiv Disc. once you look at systems then you can imagine wheel design that works best in a system like that which, i've always felt, calls for (among other things) narrow hub flanges. which is exactlyl what i had steve hed build for me back in the mid 1990s, when i had kinesis build me a fork with wider blades. what we did at QR back then didn't come close to the designs i name above, but what we did worked pretty well, i think, based on what we had to work with.
what will change is the approach. we're making motorcycles now. motorcycles without engines. that requires new thinking. the whole idea of taking a wheel to the wind tunnel will vanish.
You (and I) wondered why they didn't provide 28mm aero data. I wondered if the reason is 28 is less aero than 25 or 26 as Josh found.
I have no doubt there is still room for system improvement. I do believe in opportunity with fork width and fork/wheel interaction.
I also remember a podcast with one of the Look engineers who said wide was an opportunity for tri spokes to make a comeback. That may be interesting
I am chomping at the bit to get a new bike but have to admit I would not know what to but if I had to tomorrow morning. At this point I'd probably go Hed-hooked.
I just need to find a person that has these wheels. I have all I need to prove/disprove their performance on road. I just don't have the wheels and I'm not paying that price to find out :-)
maybe you're right. but i think it's more likely that it's what they said it was: you'll note that the entire round of testing, and what they displayed, had a common theme: testing the current wheels against their prior wheels, and showing you and me the difference in performance between them. they choose a testing paradigm for the wind tunnel that parallels everything they've done for years. but in my opinion there was a blind spot in their thinking. what changed this year is the move to 28mm as the optimized width.
i'll just clue you in on something i didn't write previously because i didn't think it was relevant, but maybe it is. when the zipp folks first came out with their new hookless wheels, and that was back in 2019 or so, they were prickly every time i said that i thought this was brilliant tech, but best for 28mm. they were really insistent that i understood that these wheels were usable with 25mm tires, with the exception of the 303 Firecrest and the 353 NSW. fast forward to today, i don't write for zipp, i don't speak for zipp, but i think i sense a change in posture. as the Crr testing has proven (to their satisfaction) the utility of this wider tire, i sense they're all in on 28mm now.
i write this because i wonder when the wind tunnel testing was done, and when the Crr testing was done. i wonder where along the progression in their thinking this change occurred (if there was a change). if the wind tunnel testing was done quite a while ago i could see why they might've just stuck with the 25mm tire for continuity purposes. if zipp were to take these wheels to the tunnel today, they might test them with 28mm tires. but i'm just guessing.
Dan Empfield
aka Slowman
Re: New Zipp 858 NSW and 808 [Slowman]
[ In reply to ]
Slowman wrote:
Tom A. wrote:
marcag wrote:
Tom A. wrote:
Hoo boy...I go out for a ride on a Sunday morning and all confusion breaks out... ;-)
Sorry. My fault :-)
Nope...you weren't the only one confused by those plots and their presentation. Not our fault...
what's confusing you? perhaps i can help. i have questions, for sure. but none of these charts have me confused.
I guess I wasn't clear enough above. The most confusing (or, perhaps, a better term would be "least enlightening") graphs are the delta plots, with no explanation of the baseline at each data point. It would be REALLY easy for them to show the baseline curve, and the rest of the curves for that matter, and THEN show the delta plot. The delta plot is really just a refinement of the data presentation. Without the original data, it's tough to put into context...especially if it shows (as these plots seem to indicate) unexpected behavior based on previous data/knowledge/modeling.
edit to add: Secondly, is the lack of details and transparency in the rolling road setup and protocol. IF they're using that data to point to these products somehow behaving differently than others do, then I think additional scrutiny of that methodology is warranted. Especially if the data from that methodology somehow doesn't match well with previously established methods.
It just seems like a bunch of hand waving right now...reminds me of the "old days" of wheel claims, actually ("It's faster...trust us!")
http://bikeblather.blogspot.com/
Re: New Zipp 858 NSW and 808 [Tom A.]
[ In reply to ]
Tom A. wrote:
Slowman wrote:
Tom A. wrote:
marcag wrote:
Tom A. wrote:
Hoo boy...I go out for a ride on a Sunday morning and all confusion breaks out... ;-)
Sorry. My fault :-)
Nope...you weren't the only one confused by those plots and their presentation. Not our fault...
what's confusing you? perhaps i can help. i have questions, for sure. but none of these charts have me confused.
I guess I wasn't clear enough above. The most confusing (or, perhaps, a better term would be "least enlightening") graphs are the delta plots, with no explanation of the baseline at each data point. It would be REALLY easy for them to show the baseline curve, and the rest of the curves for that matter, and THEN show the delta plot. The delta plot is really just a refinement of the data presentation. Without the original data, it's tough to put into context...especially if it shows (as these plots seem to indicate) unexpected behavior based on previous data/knowledge/modeling.
edit to add: Secondly, is the lack of details and transparency in the rolling road setup and protocol. IF they're using that data to point to these products somehow behaving differently than others do, then I think additional scrutiny of that methodology is warranted. Especially if the data from that methodology somehow doesn't match well with previously established methods.
It just seems like a bunch of hand waving right now...reminds me of the "old days" of wheel claims, actually ("It's faster...trust us!")
i don't suffer from the lack of that underlying data you ask for. i don't feel i need that data to understand what zipp is trying to express with these graphs. however, i respect your view and honor your background in this, so i don't mean to minimize your desire to see the data not supplied.
as to the rolling road, i might misremember but i think this is the second time "lack of transparency" has been used as a descriptor in this thread and, again, unless i misremember you've been the user both times. to me, this connotes and intentional act to withhold data. i gave you the protocol. rider aboard, 85 kilos rider + bike, roll up to speed for 30sec, the test runs for 90sec, rider dismounts. there were 96 total runs. there were 24 set ups tested (a given wheel with a given tire width at a given pressure). to me, dividing 96 by 24, that means they performed 4 runs per set up. zipp says the rolling road is a "standard" to use their word road surface, analogous to their eagle creek field testing circuit.
if what you want is a picture of the rolling road, i'm pretty sure one could be provided. do you want the speed of the rolling road? the speed of each test? i'll ask. but i don't see the lack of transparency you see. perhaps you could tell me what it is you don't see and i'll see if i can get it for you. just, if you're going to ask for data beyond that which is typically given by drum testers, such as you or al or BRR, then i have to cry foul. sauce for the goose and all that.
Dan Empfield
aka Slowman
Re: New Zipp 858 NSW and 808 [Slowman]
[ In reply to ]
Slowman wrote:
following on my post just above, here's the 404 firecrest released maybe 2 years ago? i think? this is kind of an outlier on wheels like this, with fat inner bead widths and especially (but not exclusively) hookless. this should've given me a clue about the 808 firecrest just launched.
here's the 808 firecrest. i suspect - but don't know for sure, because i don't have it - the 858 NSW is fatter. but i don't know. cyclingtips was right, at least about the 808.
Check me if I'm wrong...but doesn't the "rule of 105%" apply to the WIDEST section of the rim, which is not necessarily right at the rim edge (i.e. what we used to call the "brake track")? Just thought I'd point that out for future measurements you take.
Also, don't forget that this ROT is referring to the point at which aero degrades "too far", and not so much the "optimum" ratio for aerodynamics. THAT is why an 25mm tire on these new wheels may be still significantly faster than if they have 28mm tires on them. It's OK for Zipp to test the new wheels with the 25mm tire "for consistency of comparison sake" to older data, but they really need to show what happens when it has the 28mm tire on there, since that's how it's going to be used (per their recommendations). You KNOW they have that data (if they didn't take that data, that brings up some big questions), so not showing it implies there's something there they don't want the consumers to see.
http://bikeblather.blogspot.com/
Re: New Zipp 858 NSW and 808 [Tom A.]
[ In reply to ]
Tom A. wrote:
Slowman wrote:
following on my post just above, here's the 404 firecrest released maybe 2 years ago? i think? this is kind of an outlier on wheels like this, with fat inner bead widths and especially (but not exclusively) hookless. this should've given me a clue about the 808 firecrest just launched.
here's the 808 firecrest. i suspect - but don't know for sure, because i don't have it - the 858 NSW is fatter. but i don't know. cyclingtips was right, at least about the 808.
Check me if I'm wrong...but doesn't the "rule of 105%" apply to the WIDEST section of the rim, which is not necessarily right at the rim edge (i.e. what we used to call the "brake track")? Just thought I'd point that out for future measurements you take.
Also, don't forget that this ROT is referring to the point at which aero degrades "too far", and not so much the "optimum" ratio for aerodynamics. THAT is why an 25mm tire on these new wheels may be still significantly faster than if they have 28mm tires on them. It's OK for Zipp to test the new wheels with the 25mm tire "for consistency of comparison sake" to older data, but they really need to show what happens when it has the 28mm tire on there, since that's how it's going to be used (per their recommendations). You KNOW they have that data (if they didn't take that data, that brings up some big questions), so not showing it implies there's something there they don't want the consumers to see.
you're right. my caliper arms are only so long. zipp makes it a little easier, because it's kind of off the toroidal train. where it's harder is when the rim is toroidal and when i asked bontrager if that rim is, they just haven't replied. but it's wider as you get farther from (what used to be) the brake track, and the widest i can measure with my calipers is 32mm and change. as you'll see in my post above with attached pics. i think with both zipp, ENVE and CADEX i'm getting a pretty reliable outside width.
Dan Empfield
aka Slowman
Re: New Zipp 858 NSW and 808 [Tom A.]
[ In reply to ]
Tom A. wrote:
Cajer wrote:
Also to provide another point of info, on Bigham's hour record attempt they lowered the pressure from the traditional ~200 psi to ~130 psi and round rolling resistance reductions even on the very smooth track surface even with centripetal forces providing additional load on the tires. So I am starting to believe that quite low pressures are the way to go on road.Interesting...and it matches some data shared with me a long time ago about some informal tests done at the Carson, CA velodrome. Do you happen to know what the track surface is at the velodrome Bigham used? The speculation at the time was that if tire pressures are too high (i.e. 200 psi), then the compliance of the track itself starts coming into play.
I did some tests around the local high school running track one time, which has a "compliant surface"...it had a quite dramatic effect on the measured Crr. Additionally, I know that Josh has seen in his Silca testing differences in Crr for freshly laid asphalt vs. the same surface that has "cured" for a few months. In other words, surface compliance matters ;-)
Of course, surface compliance is basically why MTB tests usually result in: "the fastest pressure is the lowest you can run without pinch flatting" :-)
Correct me if I’m wrong but the pressure drop was because instead of the 200+psi max of tubular tires, conti clinchers have a much lower max pressure (109psi I believe) so for Dan to be running the systems around 130 psi, 21 psi over the recommendation, that says a lot to me.
“The velodrome itself is 250 m (270 yd) meters long, made of Siberian spruce wood and is applied according to the UCI standards.”
Re: New Zipp 858 NSW and 808 [Slowman]
[ In reply to ]
Slowman wrote:
i don't suffer from the lack of that underlying data you ask for. i don't feel i need that data to understand what zipp is trying to express with these graphs. however, i respect your view and honor your background in this, so i don't mean to minimize your desire to see the data not supplied.
as to the rolling road, i might misremember but i think this is the second time "lack of transparency" has been used as a descriptor in this thread and, again, unless i misremember you've been the user both times. to me, this connotes and intentional act to withhold data. i gave you the protocol. rider aboard, 85 kilos rider + bike, roll up to speed for 30sec, the test runs for 90sec, rider dismounts. there were 96 total runs. there were 24 set ups tested (a given wheel with a given tire width at a given pressure). to me, dividing 96 by 24, that means they performed 4 runs per set up. zipp says the rolling road is a "standard" to use their word road surface, analogous to their eagle creek field testing circuit.
if what you want is a picture of the rolling road, i'm pretty sure one could be provided. do you want the speed of the rolling road? the speed of each test? i'll ask. but i don't see the lack of transparency you see. perhaps you could tell me what it is you don't see and i'll see if i can get it for you. just, if you're going to ask for data beyond that which is typically given by drum testers, such as you or al or BRR, then i have to cry foul. sauce for the goose and all that.
Yes, I recall your description of the number of runs above...but, what's missing is some sort of description of the equipment used and how the method was "validated". Here's a short list of things off the top of my head that could be helpful:
- How was power measured? What's the accuracy and precision of the equipment? Is the power measurement inclusive of drivetrain losses? If not, how is that handled (i.e. is gear selection fixed? Something else?)
- How well does the method detect a "known" change in Crr (i.e. the "Tom Compton Challenge"), such as what happens when mass is added to the setup? Does the Crr change in the expected way? What's the smallest change detectable reliably?
- What's the surface roughness which the test setup is attempting to duplicate? How well does it mimic that "specification"? (This is where the PSD data referenced earlier would come in handy to evaluate how well the test setup duplicates the intended surface).
- Was the same rider and bike used for all tests? If not, how do we know their "damping" is similar (for pressures above breakpoint)?
- How does the data compare (numerically) to what is found using simple roller tests and field tests? If it differs, then how...and what are the possible sources of the differences?
- How tightly is ambient temperature controlled in the test location? If it's not, is the temperature compensated for in the results (due to the somewhat important temperature effects of Crr)?
I believe all of the above have been reported and investigated for both roller and field test methodologies. I understand the desire of the Zipp Engineers to use their "rolling road" as a proxy for field testing. It eliminates translational aero drag AND puts to rest any arguments against validity from people who don't understand the "equivalence" of rollers to flat surfaces...in other words, it's slightly more "real world" for some consumers. That said, it is going to have it's own quirks, and being able to understand those quirks is the way we can put their results in context. It's just like understanding that roller testing (when done carefully) is extremely good for evaluating tire hysteresis properties (and thus Crr) for pressures below the "breakpoint" of the system. Again, it's all about context.
edit: I thought of one more (very important IMHO) piece of info on the treadmill:
- What is the thickness and material of the moving belt, and how is it supported? How does that compare to an actual road surface in terms of compliance and damping?
As mentioned above with the Bigham track discussion, surface compliance matters in these sorts of things. If the "rolling road" adds compliance and damping into the system, the results can be different than "real world".
http://bikeblather.blogspot.com/
Re: New Zipp 858 NSW and 808 [Slowman]
[ In reply to ]
Slowman wrote:
Tom A. wrote:
Slowman wrote:
Tom A. wrote:
marcag wrote:
Tom A. wrote:
Hoo boy...I go out for a ride on a Sunday morning and all confusion breaks out... ;-)
Sorry. My fault :-)
Nope...you weren't the only one confused by those plots and their presentation. Not our fault...
what's confusing you? perhaps i can help. i have questions, for sure. but none of these charts have me confused.
I guess I wasn't clear enough above. The most confusing (or, perhaps, a better term would be "least enlightening") graphs are the delta plots, with no explanation of the baseline at each data point. It would be REALLY easy for them to show the baseline curve, and the rest of the curves for that matter, and THEN show the delta plot. The delta plot is really just a refinement of the data presentation. Without the original data, it's tough to put into context...especially if it shows (as these plots seem to indicate) unexpected behavior based on previous data/knowledge/modeling.
edit to add: Secondly, is the lack of details and transparency in the rolling road setup and protocol. IF they're using that data to point to these products somehow behaving differently than others do, then I think additional scrutiny of that methodology is warranted. Especially if the data from that methodology somehow doesn't match well with previously established methods.
It just seems like a bunch of hand waving right now...reminds me of the "old days" of wheel claims, actually ("It's faster...trust us!")
i don't suffer from the lack of that underlying data you ask for. i don't feel i need that data to understand what zipp is trying to express with these graphs. however, i respect your view and honor your background in this, so i don't mean to minimize your desire to see the data not supplied.
as to the rolling road, i might misremember but i think this is the second time "lack of transparency" has been used as a descriptor in this thread and, again, unless i misremember you've been the user both times. to me, this connotes and intentional act to withhold data. i gave you the protocol. rider aboard, 85 kilos rider + bike, roll up to speed for 30sec, the test runs for 90sec, rider dismounts. there were 96 total runs. there were 24 set ups tested (a given wheel with a given tire width at a given pressure). to me, dividing 96 by 24, that means they performed 4 runs per set up. zipp says the rolling road is a "standard" to use their word road surface, analogous to their eagle creek field testing circuit.
if what you want is a picture of the rolling road, i'm pretty sure one could be provided. do you want the speed of the rolling road? the speed of each test? i'll ask. but i don't see the lack of transparency you see. perhaps you could tell me what it is you don't see and i'll see if i can get it for you. just, if you're going to ask for data beyond that which is typically given by drum testers, such as you or al or BRR, then i have to cry foul. sauce for the goose and all that.
I think the issue is exactly that there isn't enough transparency with this testing. All the claims they are trying to make are that their rolling road is a good simulation of real world with no data to back it up or even details on what type of road surface is being simulated especially as road surfaces are super variable.
Along the same note people even don't believe wind tunnel test and that's very well established with decades of validation and everyone is well aware of the assumptions and limitations involved in wind tunnel testing. Asking other engineers to believe an entirely novel setup without any validation or even pictures/description of the setup shown to them is going to be an uphill struggle. Listing out the number of runs, rider weights, how long they road for before testing isn't really useful in my opinion. That's small peanuts and is taken as a given that those things are controlled. The real important questions are as mentioned before behind the actual rolling road setup. As if that doens't simulate road riding or the representative surfaces I or others ride on, the results won't be meaningful no matter how much control there is of test setup. I want to believe that it simulates actual roads well, but having experience building test apparatus to simulate real life events, I know how difficult that is.
This is part of the reason the track "data point" I mentioned is so impactful to me. We know the test apratrus is good (the track), the main source of error (the rider) likely well controlled due to rider skill, and the test setup is likely good. Plus this is on very smooth surfaces which is a regime with sparse low pressure data. If much lower pressures are good on smooth surfaces, then it's a given that they will be good on rougher surfaces. Instead most of the testing thus far has been on quite rough surfaces which makes me believe that the benefits aren't there on smoother surfaces, and that this testing (if it is an accurate simulation of road riding) represents rougher surfaces to show a larger benefit.
Echoing what Tom said I'd like to know the following about the rolling road testing and will likely have more follow on questions once I see a diagram of the rolling road setup and a picture/cross-section of the surface. However I'll assume the Zipp engineers have the normal environmental, sensor setup, and sample preparation variables well under control.
- Do you have a diagram of the surface of the rolling road setup?
- How is each section/plank of the rolling road supported when rotating through the treadmill/how large is each section?
- What does the transition between sections/planks of the rolling road look like?
- Do you see periodic events correlating to the load/unloading of a new section/plank or the transition between sections?
- How is the micro/macrotexture on each section/plank of the rolling road applied?
- What surfaces are you trying to simulate?
- Do you have PSD's between the rolling road and the surfaces you are trying to simulate?
Slowman wrote:
delta force, delta drag, delta power. i don't know why you don't know what this means, unless i didn't explain it well enough in the article (which might be the case). it's the difference between the performance of prior wheels zipp made and these new wheels they replace.I know what it means philosophically. I don't know how the charts are trying to represent it.
For instance, if the "delta" is the difference from the old wheel, then why does the first chart have values for the old wheel that aren't at zero on the y-axis? Shouldn't it be at zero difference from itself? The second chart does have the old wheel at zero, does this mean that the first chart is referenced to the 808 data? But even then, the 808 data doesn't cover the entire portion of the x-axis used by the other wheels, so what is the new-wheel data at those pressures in reference to?
Quote:
as i understand it, you're asking for the underlying data from the prior wheelsI'm asking how the charts show the change from that underlying data to the new wheels.