Power Meter Question
rstabler11
Posts: 67
Hi all,
I was reading about power meters and trying to understand how they work. As far as I can tell, the crankset / pedal meters all measure some degree of flex associated with pushing on them and convert that into power (I still don't really understand how the hub meters work). I know all the pro-riders use power meters, but surely it would be better to use a crankset that was so stiff there wasn't any flex? Or is this just not possible and flex is being measured at the nanometer level?
Basically, does anyone know if power meters are generally not as stiff as other top of the line cranksets (that just focus on stiffness and weight)?
Thanks,
Rob
(PS don't worry I'm not going to buy one or anything I'm just curious).
I was reading about power meters and trying to understand how they work. As far as I can tell, the crankset / pedal meters all measure some degree of flex associated with pushing on them and convert that into power (I still don't really understand how the hub meters work). I know all the pro-riders use power meters, but surely it would be better to use a crankset that was so stiff there wasn't any flex? Or is this just not possible and flex is being measured at the nanometer level?
Basically, does anyone know if power meters are generally not as stiff as other top of the line cranksets (that just focus on stiffness and weight)?
Thanks,
Rob
(PS don't worry I'm not going to buy one or anything I'm just curious).
0
Comments
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They do use the best and strongest cranks. They're not losing any energy.0
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They all use strain gauges
http://en.wikipedia.org/wiki/Strain_gauge
http://en.wikipedia.org/wiki/Wheatstone_bridge
the very slight deflections in the crank, pedal axle or wheel axle are detected and are converted to a measurment of force.
Power = Force x Velocity (speed in a given direction) (velocity is of the moving part being measured for strain, not the bike)0 -
The strain gauges for crank based powermeters aren't in the crank arms.....0
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Some are, Stages Cycling definitely is, and from what I can gather so are the new Rotor power cranks.danowat wrote:The strain gauges for crank based powermeters aren't in the crank arms.....
The rotor looks really cool.
http://power.rotorbike.com/0 -
jezzpalmer wrote:
Some are, Stages Cycling definitely is, and from what I can gather so are the new Rotor power cranks.danowat wrote:The strain gauges for crank based powermeters aren't in the crank arms.....
The rotor looks really cool.
http://power.rotorbike.com/
Sorry, should have said, strain gauges for decent powermeters aren't in the crank arms0 -
I can see the argument against the Stages offering being only 1 legged, though it probably still gives reasonable results for the general rider.
What is the issue with the Rotor (2 legged), and what is the issue with gauges in the arms?0
