Crank arm length

Aluminium Ohhh · Apr 9, 2013

What is the reason behind different length crank arms 170, 175, 180mm etc
Was told a long time ago longer legs suit longer arms, is that all there is to it?

Enlighten me please

suburbanreuben · Apr 9, 2013

You've got it!

Raging_Bulls · Apr 9, 2013

There's also the torque vs RPM thing to think about.

Longer arms will give you more leverage, increasing your torque. Very useful for MTB-ing. Shorter arms will be more suited to a higher cadence, which is ideal for riding on the road or on rollers.

Aluminium Ohhh · Apr 10, 2013

Due to my freakishly long legs I will be heading for some 180mm just seen then

Thanks

hamster · Apr 10, 2013

Raging_Bulls":vvf19jjp said:
There's also the torque vs RPM thing to think about.

Longer arms will give you more leverage, increasing your torque. Very useful for MTB-ing. Shorter arms will be more suited to a higher cadence, which is ideal for riding on the road or on rollers.

This argument is always trotted out - however there is also chainring size to consider. If you have difficulty turning the crank then fit a smaller chainring!
The torque is only at the BB shaft - in reality what matters is the tirque at the rear hub, which is affected by the gears.

You need the right length for your legs - too long and you over-articulate the knee, which is inefficient and also increases the risk of injury. Too short is inefficient also.

Barneyballbags · Apr 10, 2013

If in doubt, get 175s

stumpjumper1990 · Apr 10, 2013

Barneyballbags":oxwlu2x9 said:
If in doubt, get 175s

Or 177,5!

feetabix · Apr 10, 2013

i go from 165 on a road bike to 175 on some mtbs........with plenty in the middle.......remember its not what sits between the legs that matters, its whats inside them.......just get out and ride!.....

Raging_Bulls · Apr 10, 2013

feetabix":3i7w36lf said:
remember its not what sits between the legs that matters

That's what she said.

merckx · Apr 11, 2013

180s are bloody hard to turn over. even very tall people struggle. 175s are great for MTB. 170s if you are short or female. 165s or so if you are a downhiller on a long travel bike and want to avoid pedal strikes.

Crank arm length

Aluminium Ohhh

Retro Guru

suburbanreuben

Old School Grand Master

Raging_Bulls

Sbike Fan

Aluminium Ohhh

Retro Guru

hamster

Retro Wizard

Barneyballbags

Old School Grand Master

stumpjumper1990

feetabix

Raging_Bulls

Sbike Fan

merckx

Senior Retro Guru

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