Road surface effect on speed?
 

I do the vast majority of my riding on fairly rough chipseal roads. I notice on the few true asphalt paved roads on my routes that I'm able to maintain a higher speed. However, I don't know if this is just a psychological effect or if there is a measurable difference in rolling resistance and/or power required. Anyone have any data showing differences in speed between different road surface types?

I don't have any data.

Some data here: http://www.biketechreview.com/forum/...-testing-notes

Also, search the above forum for posts by 'AFM' with crr and road surface, you should find some more info. AFM tests lots of tires and publishes the results periodically.

Your empirical data is correct. Chipseal sucks the life out of you.

New ashphalt is speed +1.

to a point, smoother = faster, all other things remaining equal

Freshly laid asphalt is like slicks, and chip seal is like knobbies.

Uniform = less friction.

Friction is not relevant to rolling resistance. The tires aren't sliding on either a rough or smooth surface. The extra resistance of a rougher surface is due to the wasted energy dissipated when the bike bounces up and down.

So why'd you post?

fify

I just thought of an idea for my son's science fair project next year.

I was going to help my daughter do something with aerodynamics on the bike, and use the power meter to quantify.

Got shut down because all the ideas involved a "human subject" which was against the rules of her science fair.

Hmmmm. I'm going to have to check the rules.

I don't see the downside to that. If anything it gives you reason to build that necessary wind tunnel.

Maybe I can argue that we're going to use a bike racer rather than a human being.

I just blow a fan on me when I'm on the trainer to simulate wind....

Meh. If you're not riding the cobbles, it's no fun anyway...

http://lh4.ggpht.com/-y7yg9nhR0Lc/Su...0/DSC_1197.JPG

And that's just to the end of your driveway, ain't it? :D

Maybe pcad can be your subject. ;)

I think your upper body tenses up more to absorb the shock, and you use more energy.

corrected

I rode on "freshly laid asphalt" today.

It was so fresh my tires sunk into it. It was like riding with two flat tires.

Give it a few days to cool first (if you can, I didn't have a choice in the matter)

I recently rode on a paved road which had been roughed up in preparation for a new coat of asphalt. It had a wire mesh like texture which made my front tire wobble side to side. I slowed down some out of fear of crashing.

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.

I wish I knew what a paved road was!:lol: