Can someone do a rough power calc for me?



Aztec

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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.
 

SLS

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Sep 14, 2003
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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.
 

acoggan

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Jul 4, 2003
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I think you miscalculated air density using the forms on Tom's site. Either that, or you assumed moderate altitude...
 

SLS

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Sep 14, 2003
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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
 

Aztec

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Jul 8, 2003
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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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