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Discussion Starter · #1 ·
I have 172.5 crank length and wanna go to 175. Will I have to change my whole bike around or just the seat post length?
 

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Discussion Starter · #4 ·
It seems like everyone climbs better with a long crank arm. I don't see many people with a 172.5.
 

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longer cranks do not give you more power and are not very likely to allow you to climb any better.

172.5 is pretty standard.

Starnut
 

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Pantani was using 185, for such a small man that might suggest something.

Of course we all know that shorter cranks are used by sprinters, but we're talking about lower cadence climbing.

For me there's no way I'd want to climb with 172.5, those are fine for crits, but climbing is going to feel cramped.

I'm 6'2" and use 177.5 for everything these days.

I've tried most all the sizes out from 170 to 185 and anything smaller than 175 feels way too cramped, perhaps this guy needs to stretch out a little. I see this as no different than someone that needs a longer stem. Experiment if you have the money I say.
 

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It does have a little to do with personal taste. It is possible to go to long but damn near impossible to go to short. To long and you risk injury to the hip flexor or knee.

I was simply making a point that you're not going to increase your climbing power by going to a longer crank. Physics dictates that............ it's pretty easy; Force x Velocity = Power.


Pantani is a trite example because the dude only used big cranks on climbing stages because he would stand for 8-10 minutes at a time and use what little body weight he had to turn the cranks over. I have a DVD of him on the Alp and I think he climbed standing from the bottom to the Dutch turn, sat for two more switch backs and stood back up the rest of the way. Unless you climb like that, I wouldn't suggest it.

In the long run you're better off trying to increase velocity than force. That would increase power which would in-turn increase climbing speed, and with increased pedals velocity you have the added benefit of being able to increase speed quicker..... you're correct about trackies using short cranks for acceleration, the same principal applies to climbing. There is a reason the highest ever in-competition recorded wattage was set on a pair of 165s.

There is a recent study that (finally) does away with the myth that crank length is directly attributed to power production or that the 2 are correlated in some way.

What do I know, I run 175s with a 53/40 and weigh in at a big 143 pounds and can climb with damn near anyone? But I'm able to turn the 175s over at 100 rpms no problem in a 40x23 or 25. Moreover, I run 170s 55/42 on the TT bike and have the same wattage output on that bike as I do the roadbike...........

Crank length should be determined by fit and injury prevention, not power production.

Starnut
 

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I can't disagree with what you wrote starnut. For me it was simply a need to stretch out more.

As far as performance I can't really tell a difference until I go to the extremes of the spectrum. For me it was the 185 that didn't work or should I say felt like too much work.
 
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