nieles wrote: ↑
Mar 20, 2018 8:08 am
pretty simple. 1Kg.F is 9.80665N.M
and 1V is 1000mV
This is not true. 1Kg force is 9.8 Newtons. It is not 9.8 Newton-meters.
step 1 -> 0.25V/98.0665N.M (subtituting NM for KgF)
step 2 ->250mV/98.0665N.M (substituting mV for V)
step 3 ->2.54929mV/N.M (divide both with 98.0665 to get mV per N.M)
The correct form of this requires an assumption on the crank length, and lets assume that's 170mm or 0.17m
step 1 -> 10kg * 9.8 = 98 Newtons
step 2 -> 98N * 0.17m = 16.6 Newton-meters
step 3 ->16.6 Nm / 0.25V = 66.4 Nm/V
In practice, if you set it to this value it will read human watts that are inflated, since any and all force on the cranks shows up as torque even if it's not torque producing. Just stand on the pedal at the bottom of the stroke (=no torque to the rear wheel) and you'll have a huge signal. With a Sempu there is another fudge factor to figure in just what percentage of the forces present on the spindle are actually torque producing, since only those contribute to mechanical power. Hence the default in the CA being a lower value of 50Nm/V, but perhaps even this is being generous.
The actual best guess approximation to accurately show human watts is just to pedal at what you feel like is a power that you can relate to from riding on an exercise bike with a power readout, and then adjust the scaling to that the human watts is roughly consistent with what you expect it to be.
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