Crank Length

I’ve been working on my first fixed wheel conversion. I replaced the chain-ring and cranks, however they are causing me problems now.

The cranks I am using are short and have seriously reduced pedaling torque.

At this point, I feel I have two choices: replace the cranks with longer cranks or change the fixed gear to adjust the gear ratio.

What the the pros and cons of short vs long cranks?

Sheldon Brown’s article ( seems to suggest that there aren’t many cons with short cranks.

Logic suggests that shorter cranks require greater pedaling rpm than longer cranks to travel at any given speed, however I am uncertain how this will effect the ride; both for accelerating and skip stopping.

Does anyone have experience with short vslong cranks and can explain the practical difference between each?

Which option should i take?

Long Cranks -


  1. Greater torque due to longer arm better leverage
  2. Wont spin as fast when u go down the hill


  1. Pedal strike
  2. Toe overlap
  3. 10grams heavier lol

To clear this up:
-to achieve the same speed at the same gearing requires the same rpm, regardless of crank length. Longer cranks actually require the pedal to move faster (As they have further distance to go around the BB, in the same amount of time).

-at the same gain ratio, shorter cranks require greater rpm to achieve the same speed (because they have lower gearing).

… check out sheldon’s ‘gain ratio’.

As Vee dub has pointed out, people often ride slighlty shorter cranks on a track bike, especially if they ride on a banked velodrome, to avoid pedal strike. This problem is worse on a conversion as road frames typically have lower a BB height.

A street benefit of shorter cranks is reduced toe overlap. Overlap is less of a problem on a conversion due to slacker geometry.

How short are your cranks and how many GI are you running? Most cranks only vary from 165-175 and I’d be suprised if you noticed a “seriously reduced pedalling torque” between them.

Assuming the cranks aren’t unusually short, it will be cheaper to change the gearing (new cogs are about $20 for a decent one) and you maintain the benefits shorter cranks.

Probably worth noting that your height might determine what type of crank length you use.
Ie if you’re tall you might want to use 175mm cranks rather than 165mm.

keep your current cranks and learn to spin.

Just out of curiosity why would being taller warrant the use of a longer crank length?

The idea is the same as why taller people have larger frames: to induce the same body geometry as achieved by smaller riders on smaller frames. However in this case I’m not sure if there are any biomechanical or comfort benefits.

legz r levers too. longer legs enables use of proportionally longer cranks for similar amount of effort to smaller rider with smaller cranks.?

My current cranks are 150mms.

Atm I cant get enough torque to skip stop. I had a friend who has been riding fixed for a while to try, and he agreed i had to change the gearing.

WO, 150 is a little on the short side even by track standards. Get some 165’s and you’ll be a lot happier.