Bike Forums - Road surface effect on speed?

Quote:

Originally Posted by surgeonstone (Post 12793861)

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.

Of course you can model this.

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.