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Bumps and efficiency
Do bumpy road surfaces typically exact costs in riding efficiency?
While doing a loop that I've ridden dozens of times, I noticed that my speed had dropped almost two MPH from my norm on a section that had recently been chip sealed (as opposed to the baby's butt smooth pavement that existed previously). I didn't feel especially cooked (at least, no more than usual), there didn't seem to be any wind, and I was able to ramp the speed back up to normal after turning off the choppy surface, all of which led me to question whether it was indeed the bumpiness that was affecting me. Does anyone have any similar anecdotes? Any studies of this? Was I dreaming? I'm curious if it is more beneficial in a long ride/race where crappy roads are the norm to use 25mm tires vs. 23s. TIA, SYJ |
#2
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Bumps and efficiency
On 29 Jun 2006 12:02:23 -0700, "SYJ" wrote:
Do bumpy road surfaces typically exact costs in riding efficiency? While doing a loop that I've ridden dozens of times, I noticed that my speed had dropped almost two MPH from my norm on a section that had recently been chip sealed (as opposed to the baby's butt smooth pavement that existed previously). I didn't feel especially cooked (at least, no more than usual), there didn't seem to be any wind, and I was able to ramp the speed back up to normal after turning off the choppy surface, all of which led me to question whether it was indeed the bumpiness that was affecting me. Does anyone have any similar anecdotes? Any studies of this? Was I dreaming? I'm curious if it is more beneficial in a long ride/race where crappy roads are the norm to use 25mm tires vs. 23s. TIA, SYJ Dear SYJ, Yes, rougher surfaces slow tires down. Coefficient of Rolling Resistance Wooden Track 0.001 Smooth Concrete 0.002 Asphalt Road 0.004 Rough but Paved Road 0.008 http://www.analyticcycling.com/ForcesSpeed_Page.html If you plug those values into the calculator and use the defaults, you get speeds of 7.79, 7.68, 7.46, and 7.04 m/s, or 17.43, 17.18, 16.69, and 15.75 mph. The effect of chip seal is quite noticeable. My daily downhill speed improved nicely years ago after the wretched chip seal was paved. Cheers, Carl Fogel |
#3
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Bumps and efficiency
Yes, most definitely. For the same reason that knobby tires are less
efficient than smooth ones (on pavement, anyways). On a bumpy road, part of your energy output is used to overcome the bumps, leain less for propelling you forwards. Therefore you have to put out more energy to accomplish the same amount of horizontal movement. - - Comments and opinions compliments of, "Your Friendly Neighborhood Wheelman" My web Site: http://geocities.com/czcorner To E-mail me: ChrisZCorner "at" webtv "dot" net |
#4
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Bumps and efficiencyP.S.
If you regularly ride a good portion of chip & tar (or as I like to call
it "40 grit") pavement I would seriously consider tires no less than 25mm wide. Here in the Carolina Piedmont, where most secondary roads are of this type, you almost never see anything narrower than 25mm, even on the top level road racing machines. - - Comments and opinions compliments of, "Your Friendly Neighborhood Wheelman" My web Site: http://geocities.com/czcorner To E-mail me: ChrisZCorner "at" webtv "dot" net |
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Bumps and efficiencyP.S.
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Bumps and efficiencyP.S.
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#8
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Bumps and efficiencyP.S.
From: (BigBen)
Assuming we're talking about same model of tyre, same tyre pressure, how would that be any better than decreasing the 23mm tyre pressure a bit - say, from 120 to 110 psi, for instance?? cheers, jbr Well, it would make for an even rougher ride for one, but the problem is not so much road vibration as it is control. A 23mm tire wouldn't be any wider that the gravel it's rolling over, and narrower tires tend to e harder to keep on a line, as the road texture constantly tries to direct it's direction of travel and the rider has to struggle more to keep the bike riding straight. - - Comments and opinions compliments of, "Your Friendly Neighborhood Wheelman" My web Site: http://geocities.com/czcorner To E-mail me: ChrisZCorner "at" webtv "dot" net |
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Bumps and efficiencyP.S.
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#10
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Bumps and efficiencyP.S.
Chris Z The Wheelman wrote: ---snip--- If you regularly ride a good portion of chip & tar (or as I like to call it "40 grit") pavement I would seriously consider tires no less than 25mm wide. ---/snip--- Is this due to the perception of increased comfort, or because there is an increase in efficiency (decrease in rolling resistance) due to the fatter tires? SYJ |
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