Crank lenghts

[fester]

I'm very curious, as to what are all the various factors that dictate which cranks lenghts are ideal for a specific rider.

Most guys I know all ride 172.5 on their road bikes but 175 on their mountain bikes.

Whats the reason for the differance?

Also, I'm more like Ulrich, like to grind a bigger gear. Currently I'm riding 172.5 road cranks, but recently changed my big ring to a 54. I'm 1.78m tall and ride a medium compact Giant frame.

Where can I read more on the advantages, disadvantages of trying out say 175mm cranks?

[zakeen]

Jan uses 177.5mm

bigger is better for hills and time trial, hence hour record was broken on 190mm cranks.

i use 180mm for everything including crits. i love them.

[PNuT]

bigger is better for hills and time trial, hence hour record was broken on 190mm cranks.

yes & lance uses shorter cranks for testing....

to suggest that longer cranks are better for the above is absolutly laughable

cranks are an individual thing

[racyrich]

yes & lance uses shorter cranks for testing....

to suggest that longer cranks are better for the above is absolutly laughable

cranks are an individual thing

Crikey, I agree with PNUT!

Over the years I've moved up from 170 to 175. I can't honestly say it made me any quicker, though when I go back to 170s on my winter fixed bike I notice I can't sit in the saddle up hills so comfortably. But on the flat - marginal.
If you want to improve your climbing, spend your money on a week in some mountains!
Also, Boonen and Simoni both ride 172s. So leg length is not an issue here, just if it suits you.

[sharkman]

Last year I used 180 but found out that during the season I got slower and slower. This year I use 175 and can keep up speed much better (also my knees are causing less trouble). My advice: use what feels best!

[TiBikeNut]

I am 5 ft 8 inches and have used 175mm cranks fior both my road and mtb.... ( since nobody could fit them and they were on clearance ) I got them since I figured it I could increase the leverage I get (according to the math).... but really we're talking about 2.5 millimeters. You could offset that by sliding your butt around that much on your saddle....

Now I ride on 172.5mm, which is the "right" size for somebody my size and I dont really notice a difference. Even 180mm is about a 4% difference in length from 172.5mm. Even the circumfrence difference wouldn't be that great. I could understand if it was a like an inch difference in crank length.

George

[Cyco]

I'm with Zakeen in part, in that I believe in using the longest cranks you can, but I use them everywhere and don't have different lengths on different bikes.

The loss of speed some experence with longer cranks is not a function of crank length, but of training - if you don't do any spped training, you wont have any speed. There is NO reason you can't spin fast on 180s othere than you don't want to (I can get near 200rpm on the track with them when fit).

[53-11]

I'll be dead honest with you, after messing around with 170mm to 180mm I think it boils down to rider positioning as to how effectively you will be able to use different crank lengths.

With a high forward seat you can get more knee clearance for your torso with a long crank.

Did you you guys see how high their record holders seat was for use with 190mm cranks!

I think that was the biggest delta between a seat and handlebar I've ever seen. The guy was definitely rotated forward about the BB.

Most will criticize my statement about the seat height saying it's because he has long legs. That's true, but most tall guy frames have really slack seat tube angles so you'll never be able to get it that high and have such a big delta between the seat and handlebars.

FYI, he did this 55-11 fixed gear. No doubt the long cranks lowered the gain ratio though.

[marko]

The million dollar question. While our leg lengths can vary a good foot, the argument over 10mm goes on. Wonder if all started at 180 if we'd argue if 182.5 is better than 185 and how nuts you'd be to ride 190. I trully prefer 172.5 with my 29in inseam and couldn't imagine why 180 wouldn't feel the same for someone with a 30 in inseem. Maybe I'd tear up the whole world with a 157.25.