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Frog Whisperer
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Discussion Starter · #1 ·
does a wet road provide less rolling resistance?

I was running some errands today on one of my fixed and got caught in the rain...not hard, just enough to get a little bit of spray from the tires....for some reason it just seemed to be a bit faster and easier....

I was hesitant to hammer and see if I really could go faster (on the whole trip back vs there) due to the fact that the roads, while not REAL wet, were still wet....
 

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Stumpcake!
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Touch0Gray said:
does a wet road provide less rolling resistance?
I would think yes but not in a good way. I think that there is less rolling resistance because the water on the roads is reducing your dry road coefficient of friction....but I'm not an engineer so I could be wrong. Further I think grip is reduced so I would think you'd lose some of your effort when you really hammered.
 

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Frog Whisperer
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Discussion Starter · #3 ·
i was NOT hammering and WAS being pretty cautious...LOL.....I don't need to go down on a wet road....I KNOW the friction is reduced.......
 

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I suspect it's an illusion, but I have no hard data. Intuitively, I'd think that pushing water out of the way, and picking up water as the tires rotate, would cost you some energy and slow you down a bit. On the other hand, water flowing over and through the chain may lubricate it more and reduce the lost energy there -- but that's pretty minor anyway. I like the way the mechanical parts of the bike sound so quiet and smooth when riding in the wet. It's one of the little compensations.
 

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I know from personal experience..

... that frost can make for zero rolling resistance. Both tires moved sideways.

It seems like water plus the oils on the pavement could provide a lower rolling resistance.

TT
 

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Frog Whisperer
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Discussion Starter · #6 ·
DoubleTap said:
... that frost can make for zero rolling resistance. Both tires moved sideways.

It seems like water plus the oils on the pavement could provide a lower rolling resistance.

TT
been there...done that....HOWEVER...when I hit the ground I sure as heII "stuck" MY landing...no bounce.....no slide...BAM...an abrupt arrival
 

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Amazingly, and to the astonishment of those riding with me, I remained upright. But I now make no sudden movements when it is cold.

TT
 

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Steaming piles of opinion
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First folks, let's not confuse Crr with Cf... Two different things, and no real relationship between the two for our purposes.

That said, your observation has been noted before. One hypothesis is that the water fills in the small voids in the pavement, and as the rubber rolls over them, it seals it in. Water, being basically incompressible, effectively flattens out many of the small imperfections that the tire would otherwise compress into, increasing rolling resistance. As a result, riding in the wet is a bit closer to riding on a nice smooth velodrome.

I remember seeing someone doing the math on this, but I can't find the link now.

The loss of friction and so traction? Well, into each life some rain must fall.
 

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A countering factor is the hydrodynamic resistance. That is, your tire has to displace some of the water on the road, and that takes energy to do. In heavy rain this is going to overwhelm any reduction in rolling resistance.
 

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Frog Whisperer
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Discussion Starter · #10 ·
it was just a moderate drizzle.....not a heavy rain....I was just wondering, it was not really an observation....maybe the smoother ride or additional lubrication was the difference...
 

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I was caught in the rain Thursday evening and felt that I could ride much faster. I attributed riding faster and easier to the cooler temperature and being able to put the energy that would normally be used to keep my body cool into the pedals instead.
 
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