Crank length difference - leg length asymmetry?!?

Equipment
1

Hello, I’ve read and listened to all I can on crank length. On my MTB I run 165mm - 5’6” tall short legs long torso. My right leg is shorter then left with pelvic rotation from injury creating the asymmetry. With shorter cranks in my MTB it feels great. On my indoor road bike where I do the majority of TrainerRoad rides I have 172.5. I am struggling with this set up, pedaling on the right feels great but my left feels like it’s in my chest when hands are on the hoods.

Question is should I go to 165 on both pedals or drop to 165 just on the left pedal.

Appreciate any feedback thank you!

2

You might want to look into shims for your shoes before you swap crank lengths. They can help with various imbalances including mismatched leg length.

2 Likes
3

Thank you. More questions for you may follow!

4

If you ran with different crank lengths on either side than each leg would have (slightly) different effective gearing. Not sure how significant it’d be but over time it seems like it’d create an imbalance.

n=1, I’ve been pretty happy with shorter cranks (I’m 5’9")

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5

Interesting point! What crank length are you running?

6

162.5 on my road bike, 145 or 155 on my TT bike, 165 on my cyclocross, commuter, & track bikes.

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7

Just swap to 165s on both side, if that seems to work for you on the mtb. Doing it on one side might create strange issues.

You might also want to look into pedal.spacers to put your pedals further out - on your mtb, the BB will be wider, leading to a wider stance (q-factor), so maybe you need to re-create the on the road bike.

2 Likes
8

Interesting and great point about q-factor. Thank you for replying.

9

Unless the circumstances are extreme, you should have the same crank length on both pedals.

I know what you mean: I have 165 mm on my road bike and 175 mm on my mountain bike. Pedaling at higher cadences on my mountain bike feels very unnatural and unbalanced. (I also switched to shorter cranks for a better bike fit.)