Road Cycling - 172.5mm vs 175mm cranksets?

I am 6'3", and about 200#. My 60cm bike came with a 172.5mm crankset, but I thought of getting a better set, and possibly going to 175mm.

What are the pros and cons of going to a slightly longer crank for my size? Are there any real clearance issues to deal with? It is such a small differance.

Patriot

I think for your size you would want a 175 crankarm, i am suprised any bike that came in your size didnt come with them already.

I am beginning to think a 175mm as well is what I need. I have a 34" inseam, and my cadence is around 85-90 or so. Maybe the slihjtly loger crank will be a benefit.

Patriot

Get real!!!!!

You are 6'3" tall????? ditch the toy cranks and go strait to 180's. You will love them!

Get real!!!!!

You are 6'3" tall????? ditch the toy cranks and go strait to 180's. You will love them!

That is what I was thinking...anything less is going to feel like trike pedals

You've probably heard the doctrine: longer cranks = more torque but it's harder to get the revs up quickly, and vice versa.

I'm only 5'11.5", with a 34.25" inseam , and I comfortably rode 175s for a few years. It's a long boring story, but I don't have them anymore. I would say that you should at least be 175s.

Are you sure your inseam is 34"?

There's guys your size riding around on 180s, so you might want to really look into it.

I did hit the ground pedaling around corners with the 175s, but that was on an old 80s steel frame.

If you try the search function at the top of the page, there's plenty of similar threads.

I do have an old steel frame. Centurion Ironman to be exact. Bought it in 1990. But, I love this bike and want to refurbish it with some nicer components. I just don't want to we wiping out if I pedal around the corners etc. 180 is big, but maybe that is what I need. Still not sure. I say my inseam is 34 cuz that's the size pants I usually wear. 33x34 blue jean.

Patriot

I. I say my inseam is 34 cuz that's the size pants I usually wear. 33x34 blue jean.

Patriot

Ah, no. You've gotta measure it like this:
http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR&sex=M&units=cm

From the floor to the bony part of your crotch.

If you make a change that is 5mm or more, you should ease into it because you can hurt your knees if you knees are not used to the extra flexion at the top of the pedal stroke.

180s might be ideal for you, but they are big cranks, so I'd suggest looking right into it before you buy some. If you have a second hand store your area you might be able to pick up some dirt cheapies jusat for practise.

Not pedaling around corners is a small price to pay for the extra torque, in my opinion.

175's it took a little getting used to it and it a little goofy when I switch between the beater trainer bike, but you won't be sorry.

there seem to be less concrete theories explaining how to size crank length than there are to explain how reality television ever caught on. i googled it, because i was curious. i had one formula (with loads of data and endorsements to back it up) peg me at a 165 and one at a 173. i currently have 170s with an 80.5 cm inseam. Zinn's got some theories for the bigger man--maybe dig around over at velonews. but again, this one seems even more "personal preference" than frame size/material...

personal preference indeed... well said.

I'm 175cm tall, 55kg and have an 82cm inseam. I'm a skinny climber. I've just gone from 170s to 175s and love it. I think crank length has little to do with leg length but has to do with muscle type and style.

I can spin the 175s at 130rpm, just as I could with the 170s, but I'm now pushing a higher gear and going faster. Average cadence over a hilly 65km on Sunday was 91, so no problem with spin (down to 70rpm in the 39x23 up some of the hills).

I'm feeling a bit of muscle fatique in the lower leg - both shin and calf - I guess that's where I'm making up the extra reach, but I expect that to go with a bit of training. I didn't change my seat height.

I think powerful fast twitch muscled types are better off with shorter cranks and guys like me are better off with longer ones - leg length is less relevant. Not irrelevant, just less relevant.

cheers,
Ants

Do the 180s....I'm 5"11" and switched down from 175 to 172.5 and can tell the difference. Not sure if I would do that again....