cccorlew

I want an spd power meter. I'd prefer to save money and get the single sided version, but due to age and injury I'm not sure I have even left/right power output.

I'd love to be able to test my left/right power balance using either my Kickr Core or my old PowerTap hub-based power meter.

Being as both know cadence and power it seems like it should be possible to disaggregate the data, even if I'd have to guess which measures are left and right.

Then I'd feel comfortable going ahead and getting a single sided meter.

Possible? Stupid? Thoughts?

himespau 

I have not seen either as having that ability.

surak

L/R balance is a dynamic ratio that varies by power, torque, cadence, fatigue, etc., so even if you took a "reference" it wouldn't be of much use to know when running only a single-sided PM.

tempocyclist

Neither the KICKR Core or PowerTap hub will give you left/right power balance data I'm afraid.

unterhausen

Wouldn't you be able to tell if you got power data at a high enough rate?

himespau 

My Elite Direto XR-T claims that (if you pay for their extra annual fee) they can tell that from the hub-based power meter in their direct drive trainer, so theoretically a powertap hub might be able to (not sure a core (wheel on trainer with potential slippage) has enough accuracy. Of course both the Direto and the Powertap (in my theortical example) probably wouldn't be able to tell you right vs left, just pedal 1 vs pedal 2 (though the Direto output does have a right and a left indicator in their sample images if memory serves - not sure how that would work).

unterhausen

I was thinking a person would be able to look at it and see if there was a big discrepancy. I have a powertap hub but I have never used it

himespau 

I think you're right that it should be able to do that. I had a tumor eat the top half of my right fibula, so my hamstring attachment and LCL had to be attached to my tibia instead after the tumor was removed (the had been hanging loose after their normal attachment points were destroyed by the tumor), so my right and left legs have different lengths and angles of the hamstring around the knee. I would expect that there is some sort of difference between the 2 legs, and that level of difference is likely detectable by that. I can definitely see a difference in how many reps of balance/aerobic exercises I can do in each leg even 3+ years later, so a powertap should be able to see that every other power pulse is a bit different, I would imagine even if it didn't know which was right and which was left. My knowledge of my body would be able to fill that in.

RChung

You'd need high frequency (maybe around 64Hz or so) reporting in order to have a chance at that. The G2 and G3 hubs sample that high, but they don't report that high: the ANT+ standard is to report at 4Hz. If you had a G3 hub and an ANT+/BT cap, you'd still have to reprogram the firmware to transmit at a higher frequency.

Oddly, single-sided Stages have a hgih freq 64Hz mode. The data are very messy and noisy but post hoc it could be possible to figure out the putative bias from assuming that L/R balance is 50/50. But that would be a pain in the rear.