Crank Length differences....

[CAS]

As a non-giraffe, 175s are OK on the MTB and singlespeed, 170's for normal road use. Never tried 165's, would probably love 'em.

Being most definitely a "non giraffe" I've succumbed to advice from from a couple of other short riders and put 165 cranks on my latest bike. I think they are great, seem to cut strain from the top of the pedalling action. I have 170s on my other bikes which are fine but I was surprised how much difference the 165s seem to have made.

I wonder if it makes more difference to smaller riders than taller - a much taller friend reckons he can ride with various crank lengths quite comfortably!

 

[dyna-ti]

Some doctor once told me that your arms and legs are NOT exactly the same length[i dont mean arms the same length as legs i mean to each other so lets not give the wags here fuel]
Im not sure 5 mm would make that much of a difference.But to save someones knees by my ignorance ,I say keep them the same length

 

[dbmtb]

But knee pain can be caused by having a seat set too high.

Can be - but not in my case. I have short legs and big feet/long torso in comparison. Tried every saddle height imaginable..... and achieved "Zen" some years ago. 170s for spinning and 175s for pounding works for me.

 

[silverclaws]

What about a biopace chainset then ? I know bitd there was complaints that they caused knee problems, but now I am hearing they don't, they are actually better for knees than round chainsets.

 

[Sheriff]

I suffer major knee pain on most off road rides of any length, so this topic is pretty interesting for me!
I've always used 175mm cranks, the same ones for the last 10 years. I used to ride lots of DH/playing around with my saddle low. On seeing a doctor he said the outer quad is over developed from running the saddle low, which in turn pulls my knee cap across to the side of my leg.

Now I'm running my saddle higher (read: where it bloody should be) I get less pain, but could the crank length be affecting me as well?
I'm going to do the whole body/leg/wall measure thing later and see what the table says I should be running

 

[dyna-ti]

But knee pain can be caused by having a seat set too high.

Or too low
I always had my saddle very high[cos ive got big long legs ]
but my current saddle feels like its trying to castrate me :shock:
I lowered it a bit and now my lefty knee is beginning to cause me gyp
I can only contribute to me lowering it.

 

[hamster]

It's a real problem trying to generalise - also the ratio of lengths of calf to thigh is quite variable and is highly significant.

The conclusion I think is that it can be very significant for some people, and is worth experimenting if you have persistent pain.