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lesley

9 Posts

Posted - 06/09/2009 :  13:57:09  Show Profile  Visit lesley's Homepage
When making power requirement calculations for my groups human powered vehicle project, I encountered questions about rolling resistance which I have not been able to locate the answers to in my textbooks, through anyone I've asked, or through the internet.

To start, I can't find a value for rolling resistance for city tires. I can find values for road tires and a few mountain bike tires, but even those values often do not seem correct and contradict each other. I have heard I will have to contact a vendor for that. For now I have just used a range of values, but I will have to find a more specific value.

Further, how are the coefficients determined? A unitless value is given, but what all does that entail? The coefficient of rolling resistance has to be measured relative to a surface, but surfaces vary in roughness. How is that accounted for, or is there a general rule about a particular surface used for the value?

Could anyone please enlighten me on this subject and/or help me with a value to use for the calculation?

Thank you,

Lesley

n/a

2 Posts

Posted - 06/22/2009 :  06:11:52  Show Profile
just use your bike to run

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Doug Huffman

USA
2 Posts

Posted - 06/23/2009 :  04:08:35  Show Profile
Always a good place to start - http://en.wikipedia.org/wiki/Rolling_resistance

http://webphysics.davidson.edu/faculty/dmb/PY430/Friction/rolling.html

http://physics.technion.ac.il/~rutman/car/Roll-down%20test.pdf

With respect, with these fundamental questions, do you have experienced guidance.
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charlienog

Norway
1 Posts

Posted - 01/26/2010 :  00:05:25  Show Profile
.. you also have a good explanation given in "Bicycle Science" by David Gordon Wilson, p208.
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countrymike

United Kingdom
26 Posts

Posted - 01/27/2010 :  03:05:38  Show Profile
Iíve been visiting this site for some time, but only recently stumbled on the ďArchivesĒ you might start with issue no, 54, which give a series of values for CR.
Seems to me that we need a IHPVA Wiki.
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