tonyc

Hey, what size crank are you tall people using? I have a 175mm..

Retro Grouch 

I have a close personal friend who is nearly your height who insists on 180mm cranks. That's almost 1/2" different from what you've been using so that's definitely going to be a noticeable amount. Unfortunately, you're pretty much talking Dura Ace or Record to get a road bike crank that long.

tobism

I'm 5'5"... what size cranks should I be using?

aluckyfiji

I'm 5'6" on a 52cm (compact) frame and using a FSA 172.5mm crank

jeff williams

Crank arms are leg length not physical hight. Racers who 'spin fast' get longer cranks.
Racers often use cranks longer than the leg as they have the strength and want speed.

I am 5.9.5, by measure I should be 168mm, run 170, like the racey 175 ( hard on my knees). 180 is too large a circle for me to run hard.

Standard for mtb 175. Frames 18 inch and under seat tube- 170mm probably.

nutbag

very contrioversial subject; do a Google search on "crank length", and you'll find some pretty severe arguments.

I'm 5'11" with a 34.25" inseam, and in the 1990s I was using some 175s that I thought were great.
A few years ago I bought a cheap bike with 170mm cranks to commute to university,
and I rode this bike almost exclusively for two years. Then one summer I dusted off my
'good' bike with the 175mm cranks, and hammered for a month....BANG -- injured my right
knee -- took a year to get totally over it. Now all my bikes have 170s, and I'm too
scared to ever try anything else.

I obviously stopped using the 175s; I miss the leverage, but I don't miss my pedal
hitting the ground when I went around corners.

So, I suppose I'm trying to say that if you make a change, especially 5mm or more,
make sure you ease into the new length.

How tall are you? If you're my height or more, 175, or even a bit longer, should be fine.

I think, at my height, using anything over 180 would feel very strange.

jeff williams

My next bike has to be 'built' as the company assembles no bikes, has no 'kits'.

Ya, that good.... or bad .

..so when I do that one up, I will order 168mm custom crank arms.
Too expensive to just mod a bike and the diff'tween 170-175, I never really noticed. 180 different story.

If you have unusually short or long legs AND cycle more than 'regularly' or are into competitive cycling...yes, this might be a thing to check out.

Otherwise manufacturers would not have generalized as much, IMO.

And, how tall you are does not dictate your crank arm mm, it's an inseam distance\ leg extension factor.

>jef.

rmwun54

I'm 5'9" and I use a 172.5 on my road. I use to use a 170 and I felt that on the hills it never felt right to me so a friend of mine suggested the 172.5. So I did and well best thing ever. 175 on my MTB that's standard it seem.

LittleGinseng 

I'm 6'4" and I've always used a 175mm length. Coupled with an 11-21 9-speed cassette(very few hills here in NE Florida) I can usually hit 40mph on the few descending gradients I ride. My inseam is 36" and fortunately don't experience knee pain.

NZLcyclist

im 6ft with a 35"inseam and ride 175s. Can spin about 100+ rpm fairly well, down to just under 90 on the hills. Have maxed out at 196rpm downhill. Love the extra leverage over the 172.5s as I can grind over small rises on the aerobars and not change gear. 172.5s I was spinning 130+ all the time. It is certainly dependant on leg length.

Brendon

madpogue 

I'm only 5'8" (if that), but have a 34" inseam. My commuter bike originally had 175s; a few years ago I needed new chainrings, and bought a new crankset just 'cuz it cost the same as the rings alone. But instead of switching out the rings, I just switched out the whole crankset. To be honest, I didn't really notice a difference. 'Course, that's my commuter, used mostly to get to work in the winter, and run errands to the store, etc., so that kind of use might not manifest any noticeable difference wrt. crank length.

I'm running 170's on my new road bike, but only because that's what it was issued with. I'm wondering now if I should try some 175's (or 172.5's) on it. 'Course, that's the catch-22; how do you "try" different crank lengths?