Road surface effect on speed?
06-15-11 | 08:27 PM
#26
pan y agua
Joined: Aug 2005
Posts: 31,810
Likes: 1,232
From: Jacksonville
Bikes: Willier Zero 7; Merlin Extralight; Calfee Dragonfly tandem, Calfee Adventure tandem; Cervelo P2; Motebecane Ti Fly 29er; Motebecanne Phantom Cross; Schwinn Paramount Track bike
I feel the same way, to the tune of 1-2 mph. Around here 90 % of the roads I ride on are very course chip and seal. There are a couple of newly paved roads I can get on that are like Nirvana and I see an immediate increase in speed. It happens, whether or not it is psychological remains a mystery to me.
There are two main things hindering forward motion on the bike, wind resistance, and rolling resistance. Given that rolling resistance doesn't change much with speed, and that wind resistance is a squared function of speed, the answer is going to depend on speed assumed.
That said, my bet is that for a typical cruising speed, say 18-20 mph, the difference beteween a smooth new asphalt surface, and a relatively rough tar and chip surface is 1 mph or less.
Bump the speed up to a TT range, i.e. 25mph plus, and the difference drops well below 1mph; the reason being that as speed increases, rolling reistance becomes a smaller part of the equation, and wind resistance becomes the much bigger factor.
I could test it with a power meter, but fortunately we don't have a lot of tar and chip around here.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
