Crank length question

FSR_XC

I have been looking to spec a new bike and don't know which crank length would be best.

I currently own x2 MTB and a road bike. I thought being 6'1" with a 33" inside leg that I would need 175mm cranks.

However currently the MTB's both have 175 cranks and the road bike 172.5. I'm not sure I can actually tell the difference when pedaling and I am comfortable on all the bikes.

So what is the difference in riding terms and what should I spec?

dmont

Someone posted the below link in another thread the other day..Have a look at this article, hope it helps
http://www.plan2peak.com/files/32_artic ... hnique.pdf

Dmont

Bobbinogs

This is also a good article:

http://bikedynamics.co.uk/FitGuidecranks.htm

I have different cranks on two bike (172.5 and 170) and I really cannot tell any difference. Obviously, you just need to ensure the saddle to pedal height is right, which probably makes more difference, IMO.

FSR_XC

Thanks guys.

I particularly like the summary of the presentation:

*Effect of crank length is small and significant only at extreme lengths *170mm cranks will compromise power ofthe tallest and shortest riders by at most 0.5% *Pedal speed and pedaling rate interactively limit power

Crank lengths can be chosen to meet other criteria: *Aerodynamic position (shorter) *Ground clearance (shorter) *Rehabilitation or flexibility (longer)

Doesn't look like it will matter between a 172.5mm & a 175mm crank.

cougie

My thoughts precisely. I've gone as long as 177.5 and as short as 167.5. I really didnt notice the difference.

Monty Dog

I run both 165 and 170s - what I do know it that I can spin faster on 165s and they're more comfortable for long, seated climbs. I have 170s on my race bike which is better because it's mainly big gear efforts.

derosa

cougie wrote:

My thoughts precisely. I've gone as long as 177.5 and as short as 167.5. I really didnt notice the difference.

I'm the exact opposite, I do notice the difference Anything shorter than 175 and my knees start to complain.

Avezius

I did loads of on-line research before ordering my bike. Went in circles quite a lot!

I'm 5'11 but quite leggy (33" inside leg). Currently ride 170 crank. I have noticed that I have a tendency towards (and more comfortable) grinding rather than spinning, compared to my friends. Now aware of this, I now concentrate to get my cadence up.

Since I have the option, I have chosen 172.5 as I'm sure it is well within the usual range AND it might end up suiting my slower spinning style & proportionally slightly longer legs.

In practice, I expect not to be goood enough at cycling to notice any difference!