Pedal stroke and LR imbalance

I recently bought Assioma Duo and noticed that I have a slight LR imbalance ranging from 52/48 to 55/45. I have done some experimenting with positions cleat, saddle, different bikes, outdoor vs indoor etc to try to understand why. Appreciate that most people would say that everyone has an imbalance and not to worry, but I’m trying to work it out.

It seems to be roughly 50/50 when I actively concentrate on ensuring the ball of my right foot is pressed down and transferring the force of my right leg, otherwise the power feels as if it goes through the outside of my right foot instead when I let it default. Whereas my left foot does this naturally. Hope that makes sense - any thoughts on how to correct?

Cleat positions are already all the way back, which reduced the imbalance slightly.

Surprisingly there was no LR imbalance when I used a Wattbike at the local gym for 25mn, at any power.

I’ve tested across a few PMs and I’m fairly resolutely 45/55 balance. I can get that to 50/50 if I concentrate but then power drops off a cliff. It never bothered me before I knew about it and I’m faster now than I was then. In all honesty, I just don’t worry about it.

The only way it’s realistically changed what I do was to sell my LH only PMs and replace with spider based ones as I now know they were constantly reading 10% low.

Do you have any structural imbalances that are impeding power output? If not, I wouldn’t personally worry about it. I have structural imbalances but not significant enough to impact power output as far as I can tell, so I don’t worry about my LR balancing not being exactly 50/50.

Personal take is that most people don’t have structural imbalances that are impeding power output and seeing LR balance data distracts people from areas they could focus their attention and get more bang for their attention / time. For people that do have structural imbalances that impede power output I think the LR balance would be useless and physical therapy or other solutions would be needed and LR balance isn’t going to be much help.

Saddle too high maybe?

I haven’t seen anything yet that suggests pedal imbalances are an issue of any kind and that 50/50 is somehow ideal - its always just been a great example of ‘just because you CAN measure it, doesn’t mean you SHOULD…’

You legs aren’t the same length, your muscles and tendons etc on each leg will differ, your feet will be different etc etc - theres little chance your pedal action is ever going to be 50/50.

Only exception would be from an obvious biomechanical issue, but even sorting those is unlikely to result in a 50/50 balance.


I’d start with a computersized bike fit. I found out that one leg was a bit shorter than the other. I added spacers to short leg shoe. It cured alot of problems

It is possible given I fractured pelvis on the right side a year ago. Have never measured LR imbalance until this month so it is difficult to tell if this existed before.

What is clear is that I deliver more power to my right foot (or at least the LR imbalance corrects) when I focus on pushing through on the inside of the right foot. To me that feels as if power is being lost on the right with my natural riding style. Perhaps cleat wedges could sort this.

I have tried adjusting saddle height with no real impact, will try again with a significant change just to be sure.

Take the point that LR imbalance may never be 50/50 and that it can be a red herring.

In my case my left-right balance improved markedly once I went from my left-sided-only 4iiii to my Quark DZero. Yes, it only estimates left-right balance, but mine was off by quite a bit, a consistent 5–6 % bias towards my left leg. I reckon that this has increased my power numbers, my body learnt to cheat. (1 % more power produced by my left leg will read as 2 % higher power.)

Just having my left-right balance exposed on my head unit made a huge difference. It is now between 50-50 and 52-48.