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Differnce in speed from a 25mm tires to 22mm tires
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jgarza22
Jun 16, 12 10:22
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Differnce in speed from a 25mm tires to 22mm tires
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If all things being equal, lets say on a flat road with no wind, how much faster would 22mm tires be than 25mm tires?
Shg101
Jun 16, 12 15:13
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Re: Differnce in speed from a 25mm tires to 22mm tires [jgarza22]
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I wouldn't be so sure that the 25mm are any slower.
53x12
Jun 16, 12 15:14
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Re: Differnce in speed from a 25mm tires to 22mm tires [jgarza22]
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Question is which wheel are they on?
Shg101
Jun 16, 12 15:20
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Re: Differnce in speed from a 25mm tires to 22mm tires [53x12]
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53x12 wrote:
Question is which wheel are they on?
And how smooth is the road?
Jackb
Jun 16, 12 16:09
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Re: Differnce in speed from a 25mm tires to 22mm tires [Shg101]
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If you went faster by simply riding thinner tires people would be making 15 mm tires. Why stop at 22?
Fleck
Jun 16, 12 16:34
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Re: Differnce in speed from a 25mm tires to 22mm tires [jgarza22]
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There seems to be some recent evidence that 25mm for some situations is faster!
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styrrell
Jun 16, 12 16:46
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Re: Differnce in speed from a 25mm tires to 22mm tires [jgarza22]
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If all things being equal, lets say on a flat road with no wind, how much faster would 22mm tires be than 25mm tires?
I love riddles so let me be the first togive the correct answer. They will be exactly the same speed.
If all things being equal,
if Crr, Aeroness, weight, etc are equal why would one be any slower than the other?
Styrrell
devashish_paul
Jun 16, 12 17:12
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Re: Differnce in speed from a 25mm tires to 22mm tires [jgarza22]
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same psi in both?
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rickn
Jun 16, 12 18:36
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Re: Differnce in speed from a 25mm tires to 22mm tires [jgarza22]
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New issue in velonews has a wheel test (which oddly left out the zipp firecrest) where they teated wheels with 21, 23,and 25 sized tires. Each wheel responded differently. One wheel increased in drag 10 watts just from going form a 21 to 25.
styrrell
Jun 16, 12 18:58
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Re: Differnce in speed from a 25mm tires to 22mm tires [rickn]
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We're any less aero with a narrower tire?
Styrrell
devashish_paul
Jun 16, 12 18:59
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Re: Differnce in speed from a 25mm tires to 22mm tires [rickn]
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rickn wrote:
New issue in velonews has a wheel test (which oddly left out the zipp firecrest) where they teated wheels with 21, 23,and 25 sized tires. Each wheel responded differently. One wheel increased in drag 10 watts just from going form a 21 to 25.
I recently went from 22 to 25 tires. I seem to consistently be doing 150-200 kilojoules higher on a ride that used to take me ~1700 kilo joules...but I am riding on around 80 psi and my aero position is slightly worse than before. I used to ride on 95-100 psi on 22/23 tires. Not sure if the psi makes the diff, or aero drag of the tire or slightly worse aero position (probably a combo of all 3).
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rickn
Jun 17, 12 6:43
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Re: Differnce in speed from a 25mm tires to 22mm tires [styrrell]
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Some wheels tested saw a 10 watt penalty for using a bigger tire, others only saw a 2 watt penalty. But in general moving to a large tire will increase aerodynamic drag.
Another unexpected part of the test is that some wheels that were other wise equal, saw huge reductions in drag at certain angles with certain sized tires. But the reduction of drag disappeared when using tires of other size.
The end result I took from the article is that a particular wheel and tire will have a unique interaction, and without testing x wheel and y tire it is impossible to figure out for sure what the exact aero result will be. But again, as said before, narrower is more often more aero.
Murphy'sLaw
Jun 17, 12 6:48
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Re: Differnce in speed from a 25mm tires to 22mm tires [devashish_paul]
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Dev,
It's probably a combo of all 3 factors.
I'd guess RR being the lowest - wider tires are not always inherently slower. Nor is lower psi, within reason.
Aero loss from wider tires? Possible.
Aero loss from (even) less aero position? Bingo.
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M Ernst
Jun 17, 12 7:52
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Re: Differnce in speed from a 25mm tires to 22mm tires [rickn]
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I assume the question being asked because of the width of the firecrest zipps. I currently have 23's on my 303's. I'm hearing I should go to 25's at a lower psi. Any confirmation to that?
Shg101
Jun 17, 12 8:05
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Re: Differnce in speed from a 25mm tires to 22mm tires [rickn]
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rickn wrote:
Some wheels tested saw a 10 watt penalty for using a bigger tire, others only saw a 2 watt penalty. But in general moving to a large tire will increase aerodynamic drag.
Another unexpected part of the test is that some wheels that were other wise equal, saw huge reductions in drag at certain angles with certain sized tires. But the reduction of drag disappeared when using tires of other size.
The end result I took from the article is that a particular wheel and tire will have a unique interaction, and without testing x wheel and y tire it is impossible to figure out for sure what the exact aero result will be. But again, as said before, narrower is more often more aero.
So aerodynamics is all we care about?
Ex-cyclist
Jun 17, 12 8:18
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Re: Differnce in speed from a 25mm tires to 22mm tires [Shg101]
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If aerodynamics outweigh the gains of Crr then yes. Crr is basically linear, CdA is not.
There is nothing wrong with maximizing both though. ;-)
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