Crank length, changing from 175 mm to 165 mm

[dickyknees]

It helps to open up the hip angle and reduce the knee angle.

That’s how it was explained in the bike fitting.

As you say there are pages and pages of info and formulas but the feedback of actual experience here is invaluable.

Maybe I should have been riding on 170 mm and not 175 mm a long time ago and could have helped to prolong the knees even further.

 

[fair weather cyclist]

That’s how it was explained in the bike fitting.

As you say there are pages and pages of info and formulas but the feedback of actual experience here is invaluable.

Maybe I should have been riding on 170 mm and not 175 mm a long time ago and could have helped to prolong the knees even further.

I've had a bike fit recently and also was advised to shorten my cranks from the 172.5 I found standard on the bike to 170. Also was advised to swap to a shorter stem.

It's all got to do with hip/knee angle and ankle flexibility/stability. It probably won't matter in terms of your performance and it won't feel much different either. But I was told by the bike fitter that having the right crank length plays a massive role in preventing long-term knee injuries.

The guy explained that to me in technical details, which of course I did not understand as too technical of a subject. The fact is, you don't have to understand the experts; you just have to trust them

 

[Deleted member 1258]

I'm 5' 6" and run 170 on my geared bike and 165 on my fixed, the only difference I can feel is on the fixed when I'm spinning down a descent, the 165's feel more comfortable than the 170's the fixed came with.

 

[rogerzilla]

I had knee problems when I started cycling proper distances 30 years ago. 165s helped, as did exercise to wake up the VMO muscles. I still use 165s on fixies for the ground clearance and spinnability benefits.

 

[fossyant]

170mm on the Road bikes, and 175 on the MTB's as they came with them I don't notice any difference.

165mm is quite uncommon, so maybe go 170, but you are quite tall.

 

[Ajax Bay]

Steve Hogg explains the rationale for crank length and going to 165 is not radical: I have a 165 crankset for my next build (meant to be easier on the knees and encourage higher cadence). Be aware that you would be advised to address gearing at the same time. I am dropping from 52t-39-30t to 48t-38-28t. 175 > 165 is a (leverage) drop of 6%. Those hills won't climb themselves and the OP's metal knees don't want to have any more force than currently demanded of them.

 

[A1exV]

Due to me spotting a crack in my Mavic crank before a ride I had to transfer an old one on.

I ended up with 172.5 on the chainset side and 167.5 on the other.

Completely forgot about it and rode it like that for months if not years.

How and where you sit on the saddle, how you bend your ankle and knee makes a huge difference.

Would I spend money if it wasn't s problem for me?
Probably not.

Due to me spotting a crack in my Mavic crank before a ride I had to transfer an old one on.

I ended up with 172.5 on the chainset side and 167.5 on the other.

Completely forgot about it and rode it like that for months if not years.

How and where you sit on the saddle, how you bend your ankle and knee makes a huge difference.

Would I spend money if it wasn't s problem for me?
Probably not.

Forgive me for dredging up an old thread but I recently swapped out a 172.5 set of crank arms for a pair of 165’s. Having developed a tendinopathy of the hip I was looking for ways to open up that area, which shorter cranks allow me to do, enabling me to raise my saddle height and still be able to reach my pedals at the bottom of a stroke. However, I have developed knee pains very quickly with the 165’s, which shouldn’t happen. In your post you mentioned ankle mobility, which I have a limited amount of due to past surgery. Do you think this could be why I’m getting knee pain with shorter cranks ( typically known to prevent this issue)?

 

[MichaelW2]

Are the BB spindle and pedal spindles parallel. Any wonkiness in your system can stress weak joints.

 

[cougie uk]

Forgive me for dredging up an old thread but I recently swapped out a 172.5 set of crank arms for a pair of 165’s. Having developed a tendinopathy of the hip I was looking for ways to open up that area, which shorter cranks allow me to do, enabling me to raise my saddle height and still be able to reach my pedals at the bottom of a stroke. However, I have developed knee pains very quickly with the 165’s, which shouldn’t happen. In your post you mentioned ankle mobility, which I have a limited amount of due to past surgery. Do you think this could be why I’m getting knee pain with shorter cranks ( typically known to prevent this issue)?

I definitely think that reduced ankle mobility will make sorting out your ideal position harder. If you can't drop your toes then you'll need the saddle lower for one.