Hi, I’m looking for example data from a pedal-based power meter showing the 2-dimensional forces around the pedal stroke. I’m hoping to use this data in a theoretical study on frame flex – basically to combine this data with FEA modeling to evaluate whether frame flex can contaminate or otherwise affect power meter ratings.
I don’t have Vector pedals myself so I’m hoping to find some example data to work with. Is is possible to export “raw” data from these, showing radial/tangential force exterted on the pedal over the crank rotation? (not really interested in the builtin metrics like l/r balance or PCO, gimme raw force readings!) Is there any already published data like this?
Might be worth reaching out to Favero as I’m sure they will have this kind of data - unsure if they would share it.
They would probably be more receptive than Garmin though.
Intuitively I would not expect frame flex to affect power readings as the frame is independent of system under measurement.
Flex in the crank arms would potentially have an affect though because any flex in the crank would shorten the effective length of the crank arm and shrink the size of the circle that the pedals are moving in.
Unsure what (if any) affect flex in the crank arm would have
But I don’t see frame flex having any effect on the measurement… just the transfer of that power to propulsion… I think. Hopefully you will report back after your study
EDIT: the more I think about it the more i doubt myself… it’s an interesting topic.
that is sort of interesting. It might be hard to quantify due to the data rate and how stochastic that power data is. Also as noted otherwise loss of data integrity due to crank arm flex may affect the data input at the strain gauge(s) that measure the 3 d power measure. I certainly don’t know the guts of FEA but does it have any impact regarding the frame geometry and the carbon fibre lay up? Would be cool if it works but looks like a hard data set to work with.
What is the “true” power that you’re trying to measure that frame flex might distort, and at what point does it exist and is best measured? I would think in the case of a bike, the rider is turning a crank and it’s the power at the chainring, best measured by a spider PM. The rider generates this power by virtue of the component of pedal force tangential to crank rotation and the rpm. The radial and lateral components of force do not contribute to power. What effect on this are you proposing frame flex would have?
