Can someone do a rough power calc for me?



Aztec

New Member
Jul 8, 2003
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Sorry to ask something so lame of the group... Can someone calculate what the generic power required is to hold 25.5mph with a 175lb combined weight rider and bike on a flat with no wind?

Thanks for any help. I want to compare this to what my HAC4 thinks.
 
Originally posted by Aztec
Sorry to ask something so lame of the group... Can someone calculate what the generic power required is to hold 25.5mph with a 175lb combined weight rider and bike on a flat with no wind?

Thanks for any help. I want to compare this to what my HAC4 thinks.

Frontal Area 0.50 m2
Coefficient Wind Drag 0.50 dimensionless
Air Density 1.056 kg/m3
Weight 79.4 kg
Coefficient of Rolling 0.004 dimensionless
Grade 0.000 decimal
Wind Resistance 17.2 kg m/s2
Rolling Resistance 3.1 kg m/s2
Slope Force 0.0 kg m/s2
Cadence 100. rev/min
Crank Length 170. mm
Pedal Speed 1.78 m/s
Average Pedal Force 129.8 kg m/s2
Effective Pedaling Range 70. degree
Effective Pedal Force 333.8 kg m/s2
Speed 11.40 m/s
Power 231.1 watts

Here is the web page if you wish to play with the numbers
http://www.analyticcycling.com/ForcesPower_Page.html

Hope this helps.
 
I think you miscalculated air density using the forms on Tom's site. Either that, or you assumed moderate altitude...
 
Originally posted by acoggan
I think you miscalculated air density using the forms on Tom's site. Either that, or you assumed moderate altitude...

I went with 1500 feet instead of sea level & slipped the gradient down to 0 due to "flat road" - sorry I should have pointed that out. Thanks
 
Whoops -- I should've mentioned altitude. About 10 measly feet above sea level. Right along the coast.

Thanks for the help!
 

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