Power Phase Difference between 2 legs

Hey guys,

I’ve been cycling for close to 2 years, and have been fitted by a local bikefitter. However, I recently got myself access to Cycling Dynamics, and realize I have quite a distinct difference regarding the start/end of my power phase during the pedal stroke, with the right leg starts and ends way earlier than the left one.

Is there anything I should adjust, or if this is technique related which can be improved on by doing single-leg drills and others.

Please advise and looking forward to hear your opinion.

On the surface that does look like a significant difference, but with a very good L-R balance there may be another explanation. What type of power meter are you using? Is it dual or single sided? Does it have a specific orientation that needs to be achieved for installation? Anything odd like non-round chain rings?

Is this difference present at both endurance power levels (50-70% FTP) and threshold/Vo2?
I find that i get unbalanced at low power levels where my non-dominant leg just does less. If there isn’t a technical reason for the disparity, then yes some individual leg drills or even just concentrating on a toe kick and heel drag would be useful. Sorry for answering a question with more questions.

Hey Hamilton,

I’m using a dual-sided Assioma, with a standard round chain-ring. This data was from a 90%FTP sweetspot session, with 2 sets of 20mins. But on more relax ride, I actually get kinda the same trend as well.

As you also pointed out, my L-R Balance got me confused too, but with a very dissimilar power phase. Not sure what could be the cause.

I should also point out that I do have a leg length discrepancy, with left leg being the shorter one. However that was corrected with a 3mm shims during the bikefit. Both cleats are at the same location on the shoes fore-aft wise.

Just a very interesting thing to notice :sweat_smile:

My very unprofessional take: It could be leg length. Shims extend your leg below the knee, but the relative position of your knee compared to the pedal spindle is also dependent on your hips and upper leg. It feels like your shorter leg will be behind in the revolution, so the power drive would be earlier on your long leg while your short leg needs to “get over” before your quad can fire. Not sure.

I also have the Duos and think they can be trusted. Might be worth another calibration just in case.

Maybe a fitter will chime in.

Hmm but that is a good guess indeed. Anyways, thanks for the input Hamilton.

I’ll just ride on I guess, not sure if a more “balanced” power phase would improve efficiency and time-to-fatigue

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