I know that 21mm tires are faster than 23mm. However, for the life of me I can’t seem to find a quantifiable number in any of the discussions. Tom A. have you field tested this?
Apparently my ST search-fu is not working for me today…
I believe I saw something in bicycling magazine a few months back about the opposite bieng true. Something about the total contact area (was actually greater in 21’s vs. 23). I remember this because I thought the same thing (skinnier tire, less contact but less rolling resistance). Maybe writing SOP’s all day has made me lose me mind. That’s why I came here…
I believe I saw something in bicycling magazine a few months back about the opposite bieng true. Something about the total contact area (was actually greater in 21’s vs. 23). I remember this because I thought the same thing (skinnier tire, less contact but less rolling resistance). Maybe writing SOP’s all day has made me lose me mind. That’s why I came here…
Wider are faster!
http://www.cyclingnews.com/features/tech-feature-the-work-of-wheel-energy
Yes, you have been lied to your whole life.
I believe I saw something in bicycling magazine a few months back about the opposite bieng true. Something about the total contact area (was actually greater in 21’s vs. 23). I remember this because I thought the same thing (skinnier tire, less contact but less rolling resistance). Maybe writing SOP’s all day has made me lose me mind. That’s why I came here…
Sorry I was looking for Aerodynamics not rolling resistance. Some 21’s are actually faster than 23’s. It depends on the tire. AFM’s charts on biketechreview answer that question.
I believe I saw something in bicycling magazine a few months back about the opposite bieng true. Something about the total contact area (was actually greater in 21’s vs. 23). I remember this because I thought the same thing (skinnier tire, less contact but less rolling resistance). Maybe writing SOP’s all day has made me lose me mind. That’s why I came here…
I think a 21 bends more at the point of road contact and causes more resistance than a 23
Not that simple, it depends on the rim.
Some newer rims are wider and designed to test faster with the 23mm tyre. I believe the guys at FLO cycling have gone this route.
Others (my Felt TTR2 front wheel, for example) tests faster with a 20mm front wheel. Better in fact than an old style Zipp 404 front with a 23mm tyre (apparently).
all else being equal, a 21mm tire will have worse rolling resistance than a 23mm tire.
however, a 21mm tire will tend to be faster aerodynamically, by enough to offset that rolling resistance penalty, especially on front wheels.
to quantify it however is difficult, it depends on what wheel the tire is on, and how the tire is made, etc etc.
for instance on a wide C2 rim, 21mm is still faster aerodynamically than 23mm, but not by as much as on a narrower rim (typically)
bontrager produced this chart which includes aerodynamics AND rolling resistance in total drag. I cannot speak to how honest/accurate this data is though:
all else being equal, a 21mm tire will have worse rolling resistance than a 23mm tire.
however, a 21mm tire will tend to be faster aerodynamically, by enough to offset that rolling resistance penalty, especially on front wheels.
to quantify it however is difficult, it depends on what wheel the tire is on, and how the tire is made, etc etc.
for instance on a wide C2 rim, 21mm is still faster aerodynamically than 23mm, but not by as much as on a narrower rim (typically)
bontrager produced this chart which includes aerodynamics AND rolling resistance in total drag. I cannot speak to how honest/accurate this data is though:
looks like “the” number is 22
whenever I see this chart, I can’t help but wonder if the “top german brand” is of the black chili varietal. I also wonder, if the 20mm Supersonic of the same “top german brand” has the same shape as whatever 23mm tire they used which could make it a really sweet ass racing tire.
So many questions, so few real answers.
all else being equal, a 21mm tire will have worse rolling resistance than a 23mm tire.
however, a 21mm tire will tend to be faster aerodynamically, by enough to offset that rolling resistance penalty, especially on front wheels.
to quantify it however is difficult, it depends on what wheel the tire is on, and how the tire is made, etc etc.
for instance on a wide C2 rim, 21mm is still faster aerodynamically than 23mm, but not by as much as on a narrower rim (typically)
bontrager produced this chart which includes aerodynamics AND rolling resistance in total drag. I cannot speak to how honest/accurate this data is though:
I’ve obviously seen this chart, but I was hoping someone like Tom would chime in with field test data. I know Andy did some testing and I guess I could ping him at Wattage or FB. I have a hard time believing that the Bonty tire is 100grams less drag than the Zipp 21. Maybe it is, but that would definitely suggest tires are more important than wheels since most of the newer wheels are all within grams of each other.
If your only choice is those particular tires on those wheels then yes.
well that is a particular 22mm tire whose shape has been purposefully made aero.
that may be the ‘best’ tire, but doesn’t mean 22mm is the best size, innately =)
“So many questions, so few real answers.”
Welcome to sports technology.
“So many questions, so few real answers.”
Welcome to sports technology.
Right?!?
I was under the impression that the aero gain from 23 to 21 WASN’T enough to overcome the rolling resistance
I was under the impression that the aero gain from 23 to 21 WASN’T enough to overcome the rolling resistance
well give me any 19mm bontrager aerowing tires you have then!
I have dreams of walking in to bike shops and finding NOS of the aerowing. Such a good tire.
I was under the impression that the aero gain from 23 to 21 WASN’T enough to overcome the rolling resistance .
Thats way too general a statement. For one plenty of 21 tires have better Crr than plenty of 23 tires. Even for 2 tires with the same construction, where the 23 would have lower Crr, the aero disadvantage will vary greatly depending on the particular rim.
With the upper level equipment these days and the data thats available its almost impossible to speak in broad generalities and be right.
If you have 2 specific tires in mind and know which wheels they will go on, you can likely get a decent educated guess as to which is fastest.
I’d like to know where the ideal *range is. *Lets say 23 is faster than 21 (for sake of discussion).
Is 24 faster than 23?
Is 24 faster than 21?
25?
Where does a tire become too big? If you’re riding on a real crappy surface might a 24 or 25 be faster?
Also the blacktop roads get soft when it’s hot. Would a fatter tire be better? Smaller tire?
AAAAAAGGGGGGGGHHHHHHHH!
I was under the impression that the aero gain from 23 to 21 WASN’T enough to overcome the rolling resistance .
Thats way too general a statement. For one plenty of 21 tires have better Crr than plenty of 23 tires. Even for 2 tires with the same construction, where the 23 would have lower Crr, the aero disadvantage will vary greatly depending on the particular rim.
With the upper level equipment these days and the data thats available its almost impossible to speak in broad generalities and be right.
If you have 2 specific tires in mind and know which wheels they will go on, you can likely get a decent educated guess as to which is fastest.
it was an all other things being equal sort of generalization, but I think I see what your saying, that is if it’s it’s all other things aren’t equal
none of it really matters to my slow ass :-), but “free” speed is still free speed.
I spoke with a Zipp rep this summer about going with a 21 or 23 on their wheels. He asked what distance and speed? I told him Oly tris (40k) and 26+ mph. He said to go with a 19.
Not saying that this information is “time spent in a lab” but based on their engineers feedback, I thought it was interesting. I race at 120 psi and am 170lbs.