New power meter uncovers odd imbalance

I’m unbalanced. My right leg is much stronger than my left leg; 2cm larger at the thigh a few years ago when I got my body metrics measured. So when I installed my shiny new Assioma Duo on the trusty trainer bike, I expected to see the stronger right leg show through in the data, but that has not been the case. Not even close.

Upon reviewing the data of my first ride I was shocked to see a power split of 56/44 TE 90/80 PS 24/22. I’m still trying to understand the metrics, but considering how much more meaty my right leg is, this was surprising. The next workout I did I saw a balance of 57/43.

I reworked my garmin to show live power balance metrics and have seen up to 70/30 regularly through all power phases. Here is my ramp test from just last night (along with West Vidette tacked on the end). When I stand I get a much more reasonable live reading of 45/55 with the right leg (stronger) creating more power.

I have ridden for years and have had regular left hamstring injuries and have always assumed it was because it was the weaker side. Now I am wondering if it is because it has been over worked? Should I even care?

I have not tried the pedals on the tri bike so I’m not sure if a different body position will effect things yet. It also makes me want to get a trainer tire for the MTB and see what’s going on there as well.

More information:

I’m a triathlete so I record balanced power data from running as well. When I run outdoors, I am almost at 50/50 balance for ground contact time. I feel balanced and light on both feet. The data shows favor for the left leg sometimes, but not too bad.

When I hit the treadmill, my balance shifts to about 51.5/48.5 with really bad examples getting north of 53/47.

I have no idea if any of this matter, but I have found it very interesting. I had planned on getting a left side only meter for the MTB, but am rethinking whether that will give me even close to realistic data at all now.

Not speaking to the rest of the post at all, but just this part, I don’t think the surgey nature of MTB riding would give you good data anyway, for me personally, I would only want a PM on my MTB to capture total work done over the course of my ride. The conditions just don’t suit capturing accurate per leg data, unless of course, it was your primary training bike, then I’d think you might want more accuracy.

I have a pretty significant leg power mismatch as well, I had major hip surgery 9 months ago and my right leg still isn’t on par with my left, so I am going the pioneer route for my main bike and relegating the stages single leg to my cross bike, but even then I only imagine my dual sided data to be really useful when I’m doing a trainer ride or for race analyzing. my .02.

Find someone else’s dual sided power meter and confirm your findings on a second unit. Your imbalance might be real but it also might just be a bit of a wonky power meter.

Confirm the data with a separate measuring source before you make any adjustments

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I don’t really have any access at all to another dual sided PM. I’m feeling confident in it’s output because my FTP number is right in line with what my InRide sensor has given me. Also, when standing I see much more realistic balance numbers. I feel good about the accuracy of the PM.

A wattbike at a gym would give you another source to see if you get the same results.

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