165mm crank length - talk to me!

[rogerzilla]

Re:

165mm was also the traditional length for British bikes with cottered cranks, or 6 1/2" was (165.1mm).

 

[jm]

Re:

I am of the ride any length you get given but I've just been given a set of TA's nice cranks.The left is 170 the right 165.Just not quite brave enough to try it.

 

[mattr]

I have an inside leg of 33 inches

What should I expect?

Once you are used to it (5 mins) nothing.
I'm running a 32" inside leg at the moment, no opportunity to upgrade at all......

Crank length, like Q-factor, falls within the gamut of self-selectable criteria that you are (unconsciously) capable of adjusting for: ie ride what you have/like/want and ignore anyone who tells you otherwise.

Not quite true. Too long can give long term issues with knee damage.
You set saddle height to BDC, so you need enough knee/ankle/hip motion to get over TDC, too long cranks will encroach on that. And it's (usually) the knee that goes.

You can go as short as you want, until it feels weird!

I'm currently just starting the process of moving to shorter cranks across the board. 165 was massively more comfortable than 170 on the road bike, and still not sure what i should do with regards the MTBs and CX bikes..... shorter is pretty much a given, just how much!

 

[hamster]

Absolutely agree with mattr - I once did a tour on 175s (usually ride 170) and I had knee pain all the time. I recently swapped from 175 on my singlespeed to 170 and it's amazing how much smoother my pedalling is.

Match crank length to suit leg length.

 

[pigman]

Re:

I can tell the difference between 170/172.5/175 .... not had 165's since I had a cottered chainset in the 80's

if I lived in a flat area, I'd go for shorter cranks and rev like hell. I currently use 172.5 on all bikes except the pub clunker
My weakness is hills and as I ride in the Peak district and am asthmatic i've never been able to climb with a fast cadence, so I tend to churn a bigger gear (and I have Rik-van-looy style thighs so the knees don't take the strain).

longer cranks will give you far better acceleration, but will be hard on stamina as you're moving a bigger circle (pedalling further). Short cranks will let you sustain a speed for longer, but will feel like you can't power through a short hill.

Horses for courses - experiment and see what works - there is no formula to account for a whole host of physical differences.

 

[smith931]

If you are usually using 170/ 175mm then you should try 5mm higher from 165 which will be suitable for your leg and can be got more power.
When you change the crank from 170 to 165 it can be hurt for your legs and body. So, think first before the change.

 

[Stick Legs]

Peter Keen wrote an interesting article about this a few years ago and reckons everyone is on too longs cranks.

He went as far as to advocate 140mm cranks for shorter people and a maximum of about 170mm.

Damned if I can find it now.

 

[Nob]

Since 78 I've used 177.5's & feel comfortable with them. Tried shorter & long but began feeling pain around the knees etc so just stuck with my chosen length as it's what I'm comfortable with. Ride with what your comfortable with by listening to your body

 

[peetee]

Re:

Crank length does affect the flexion of the knee independently of saddle height. Longer cranks mean the distance between each foot is greater so even if you compensated to provide the correct leg extension at BDC, the other foot is sitting higher than normal and the knee is bent further than usual. I have 170's on my road bikes and 175 on the MTB. I do have knee issues that are exacerbated by the MTB but I am sceptical as to the reason being the increased crank length. I believe it is more due to the offset of the triple crank.

 

[mattr]

Yes, i don't like bandy legged Q-Factors either.......

I try my best to optimise it (too narrow is uncomfortable as well. But not as bad.)