Is crank length important for mountain biking, too?

[kaian]

On my road bike, I just put shorter (165mm) cranks on because I am short (5 feet tall with an almost 28" inseam) and I didn't want to mess up my knees. I have heard that with mountain biking, you want the crank length to be a little bit longer for climbing. So...what should my crank length be on my mountain bike?

I am planning on ordering a new bike and I want to make sure I request a length that will work well for me.

Any thoughts on this?

 

[triguy98]

I am the exact opposite of short. 6'2, in fact. The LX crank that came on the bike was 175. It worked. When I upgraded to XT, i got the 180mm cranks. WHAT a difference! More power and torque. Awsome. Without changing anything else on the bike, I found myself making climbs I hadnt been able to make before.

On my road bike, I just put shorter (165mm) cranks on because I am short (5 feet tall with an almost 28" inseam) and I didn't want to mess up my knees. I have heard that with mountain biking, you want the crank length to be a little bit longer for climbing. So...what should my crank length be on my mountain bike?

I am planning on ordering a new bike and I want to make sure I request a length that will work well for me.

Any thoughts on this?

 

[sssamcz]

On my road bike, I just put shorter (165mm) cranks on because I am short (5 feet tall with an almost 28" inseam) and I didn't want to mess up my knees. I have heard that with mountain biking, you want the crank length to be a little bit longer for climbing. So...what should my crank length be on my mountain bike?

I am planning on ordering a new bike and I want to make sure I request a length that will work well for me.

Any thoughts on this?

Bigger is not necessarily better, though as a general rule mtb cranks do run a bit longer than road. This is because the extra leverage gives extra torque - which is especially useful grinding up steep climbs as you do off-road. Therefore, you should probably try some 170s on your new bike at your height, though there is something to be said for riding the same length across all bikes as some people have difficulty adjusting between different lengths. If your lbs is particularly obliging, they may let you try some different lengths out.

Sam

 

[AzzaC]

Like road bikes, the smaller mtb's generally come standard with shorter cranks. The most common and 'standard' length of crank is 175mm.

For your height, you would probably want a 170mm crank length as 165mm would be too short and your climbing ability will not be as good. You could try something in between, but I don't think you can get 167.5mm cranks as I've never seen or heard of that size.

Hope that helps

 

[gclark8]

but I don't think you can get 167.5mm cranks as I've never seen or heard of that size.

Shimano do XTR in 165, 167.5, 170, 172.5, 175, 177.5, 180 with 44/32/22 chain rings.

 

[AzzaC]

That's probably why I've never heard or seen them. Don't see too many XTR cranksets out there. And the price for the chainrings and the cranks!

Deore XT and below, along with Race Face and Truvativ only have 5mm increments, 170/175 and 180. XT has the additional 165mm

 

[gclark8]

Yes, how true. I would just be happy with a pair of Acera/Altus/Alivio 165mm for my MTB.

 

[Solanog]

My road bike is 175 and the same for my MB. I'm 5'10", maybe 30' inseam. Would 2.5mm-5mm make a noticeable difference in climbing?