Crankarm Size Question

Sombody asked:

Quoted message said:

I looking at buying a new set of cranks. What is the deciding factor between 170mm and 175
mm cranks?

See: sheldonbrown.comcranks.htmlOpen ↗

Sheldon "Cranky" Brown +--------------------------------------------------------+
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+--------------------------------------------------------+ Harris Cyclery, West Newton,
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Sheldon Brown <[email hidden]> wrote in news:3E9C3788.3010303 @sheldonbrown.com:

Quoted message said:

sheldonbrown.comcranks.htmlOpen ↗

Great site! Thanx a lot!

Biggibby

Biggibby said:

I looking at buying a new set of cranks. What is the deciding factor between 170mm and 175
mm cranks?

Leg length, IMO & E. As a rough guide: 170 for average legs, 175 for long.

I find the theory that there's no downside to too-short cranks absurd. Imagine trying to pedal a
bike with ridiculously tiny cranks, say 60mm long. Oh yeah, that'll be very enjoyable, wouldn't it.

You need to turn your legs in a comfortably-sized circle so it makes sense to get cranks most
suitable for _you_. It's true that manufacturers don't provide enough choice to cope with everyone
but that's no reason to get the nearest to optimum length you can when next buying cranks.

Don't forget the difference of the circle diameter created by 175mm cranks as opposed to 170's is
10mm and not 5mm.

~PB

Sheldon has the meat of it, as usual.

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": geocities.comczcornerOpen ↗

Quoted message said:

I find the theory that there's no downside to too-short cranks absurd. Imagine trying to pedal a
bike with ridiculously tiny cranks, say 60mm long. Oh yeah, that'll be very enjoyable, wouldn't it.

Yeah, and 400 mm cranks would be quite a change as well! But the difference between 170s and 175s is
small, so either way, most people can accomodate easily.

Quoted message said:

Don't forget the difference of the circle diameter created by 175mm cranks as opposed to 170's is
10mm and not 5mm.

This means that out a 340mm circle, you have 10 mm increase in diameter, or about .4 inches in
13.4 inches.

Might need one to change the seat height a tad.

I ride 170s, 172.5s and 175s, I believe that I can notice a difference between the 170s and 175s but
it is only to notice it.

As long as the cranks are not too long, there seems to be little difference in performance.

jon