At 06:18 AM 5/22/2011, you wrote:
>Just a thought.
>
>I wonder if there's an easy way to calculate the power output of a human
>pedaling on a bicycle. The only idea that comes to mind is some sort of
>method to sense the torque applied to the wheels, and then calculate the
>power output from there using classical mechanics. How would one go about
>sensing the applied torque though? The ideas I'm currently thinking of don=
't
>seem practical for installation in a normal bicycle - such as a pressure
>sensor at some point  along the radius of the hub, sensing the arc pressur=
e
>and calling that "force at radius" (torque).
>
>Or - how about pressure sensors on the pedals? The applied pedaling force =
is
>directly related to the torque. Human power output can be calculated from
>there. But then there's the issue of bogus pressure applied by the body
>which doesn't actually go into doing any work (for example, when standing =
on
>the pedals).

Power =3D (force * distance) per unit time.

There are a number of commercial products that offer direct power measureme=
nt:-
http://www.westbrookcycles.co.uk/transmission-components-c189/chainsets-c75=
/sram-2010-s975-srm-power-meter-crankset-p35922
http://www.powermeters.org.uk/cycling/cycleops-powertap-elite+-mtb-hub-only=
/104379149/2698/
http://www.powermeters.org.uk/cycling/cycleops-powertap-elite-plus-wheel-sy=
stem/40926216/1857/

Plus, apparently, some less convincing products that attempt to estimate
opposing forces, which does away with strain gauges and, most likely,=20
accuracy.

Not particularly cheap, but I doubt it's a very big market.

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the rewar=
d"
speff@interlog.com             Info for manufacturers: http://www.trexon.co=
m
Embedded software/hardware/analog  Info for designers:  http://www.speff.co=
m



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