Crank Length for the shorter chaps out there...

What size cranks do you have ?

170mm or larger
15
79%
165mm or smaller
4
21%
 
Total votes: 19
CoffeeNut
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Crank Length for the shorter chaps out there...

Postby CoffeeNut » Tue Jun 17, 2008 8:24 am

I'm 173cm with a 79cm inside leg.
Apparently, my ideal/optimal crank length is 163mm.

This poll is for those guys/gals who are less than 180cm tall...

What crank sizes are you using ?

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LuckyPierre
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Postby LuckyPierre » Tue Jun 17, 2008 8:43 am

I'm 178cm. I don't know what my in-seam measurement is, but I ride with a crank centre to seat top effective measurement of 79 cm. I use 172.5mm cranks on the road and 175mm off-road, although I'm experimenting with a 170mm crankset from time to time.
Edited - oops, I just noticed that I'd put 'cm' in my crank sizes :oops:
Last edited by LuckyPierre on Tue Jun 17, 2008 3:02 pm, edited 1 time in total.
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lukas
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Postby lukas » Tue Jun 17, 2008 8:48 am

I'm about 177cm and I've always used 172.5mm cranksets.

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barefoot
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Postby barefoot » Tue Jun 17, 2008 9:16 am

Not exactly short (178 or so), but short in the leg (generally wear 30" inseam pants, which calcs out to 76cm).

Several of my bikes have 175s, because that's what bikes tend to come with. I've had a few shorter cranksets, and I like 'em. I would struggle to pick the difference between 170s and 175s without checking the stamping/castings on them, but a few times I've had a bike feeling just right, and noticed later that the cranks are 170. Or even 165 (I think that crankset is on Mrs Barefoot's bike now - I should claim them back).

tim

Wollemi
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Postby Wollemi » Tue Jun 17, 2008 10:04 am

'Crank Length for the shorter chaps out there...'

What? I am 173cm tall, with a 79cm inside leg, too. I frequently stand significantly taller than other commuters when standing on packed Sydney trains. You are by no meets 'shorter', unless of course cycling tends to attract taller guys, who have a better natural mechanical advantage to inspire them to stay with the pursuit.
Give up cycling and move to Sydney to utilise the public transport so as to overcome your inferiority complex!

Seriously - why is the calculator telling me I should be using a shorter crank? I have only ever used 175mm cranks - becuase that is what the MTB's I have bought from bicycle shops are sold with. Would my irregular cycling and commute of 34km improve if I went for a shorter crank?
Live every day as though it is your last - one day you will be right...

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Kalgrm
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Postby Kalgrm » Tue Jun 17, 2008 10:29 am

What I have and what I'm going to put on my bike are two different things.

I've got 175s on my MTB, and they're fine for the riding I do on it.

I've also got 175s on the recumbent, but I'll be putting 150mm cranks on it as soon as I can source some. Spin is king on the 'bent, so shorter cranks are where I'm headed.

Horses for courses, right tool for the job, etc.

Cheers,
Graeme
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lisanne
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Postby lisanne » Tue Jun 17, 2008 11:27 am

I am 164cm's and both my bikes (road and track) came with 165 cranks but that is probably cos of the size of the bikes :roll: hehe

CoffeeNut
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Postby CoffeeNut » Tue Jun 17, 2008 11:52 am

Knew I would get a few bites there :)

I'm no expert, but do like to approach these things from a technical or scientific angle, as well as the 'feels right' angle.

If the crank is too long for your leg then:
1. Your knee angles will be too high, potentially leading to excessive stress/wear on your joints.
2. The longer the crank the more the mechanical advantage - so if your gearing is too steep you can 'survive' this better with cranks that are too long. Ideal cranks may force you to ensure the ideal gear ratio's for the terrain you are in most of the time.
3. Crank length, knee angle, and frame size are all somewhat inter-related - so you can change a few variables to find your fit. Assessing or thinking about crank angle seems a natural part of that process I guess.

I am no expert - I've just paraphrasing a few hours reading and mulling over the potential impacts.

I'm seriously thinking about 165mm cranks IF I do change my front chainring setup.

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Kalgrm
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Postby Kalgrm » Tue Jun 17, 2008 12:17 pm

3. Crank length, knee angle, and frame size are all somewhat inter-related - so you can change a few variables to find your fit. Assessing or thinking about crank angle seems a natural part of that process I guess.

This point is very important. I can easily swap to a 150mm crank without effecting the fit of my bike because it doesn't have a top tube, seat tube, fore and aft seat positions, bar height, etc. for me to worry about. On the 'bent, I simply move the seat back about 25mm and pull the bars back to suit.

On a conventional bike, shortening the crank by that much means raising the seat to allow correct leg extension. It also means move the saddle back a little (if KOPS is your thing), which then means getting a shorter, higher stem which in turn may lead to an unbalanced ride. In short, getting 150mm cranks on a conventional bike would necessitate a rethink on frame design if you're to do it properly.

Cheers,
Graeme
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Andrew69
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Postby Andrew69 » Tue Jun 17, 2008 4:39 pm

172cm, 175mm crank, no problems to date, even with crappy knees.
But I am careful to keep my cadence high

MountGower

Postby MountGower » Tue Jun 17, 2008 5:22 pm

177cm and a mix of 172.5 and 175. I can't tell the difference.

Dunk
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Postby Dunk » Wed Jun 18, 2008 10:31 pm

I'm 167cm;

Track Bike: 165mm
Road Fixie: 170mm
Road Bikes: 172.5mm
Mountain Bike: 175mm
Single Speed 26" MTB: 177.5mm
Single Speed 29" MTB: 180mm

I guess I've got nearly every length covered, though I have sometimes run 167.5mm and 170mm on the track for various events.

geoffw
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Postby geoffw » Mon Jun 30, 2008 2:20 pm

im 172cm, roadie 175mm trike 150mm

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Andrew Grace
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Postby Andrew Grace » Tue Jul 01, 2008 8:31 pm

I'm 173cm tall and I have only ever used 170mm cranks.

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toolonglegs
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Postby toolonglegs » Tue Jul 01, 2008 9:01 pm

Dunk wrote:I'm 167cm;

Track Bike: 165mm
Road Fixie: 170mm
Road Bikes: 172.5mm
Mountain Bike: 175mm
Single Speed 26" MTB: 177.5mm
Single Speed 29" MTB: 180mm

I guess I've got nearly every length covered, though I have sometimes run 167.5mm and 170mm on the track for various events.


whats next on the shopping list then? :D .

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mikesbytes
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Postby mikesbytes » Tue Jul 01, 2008 10:53 pm

Dunk wrote:I'm 167cm;

Track Bike: 165mm
Road Fixie: 170mm
Road Bikes: 172.5mm
Mountain Bike: 175mm
Single Speed 26" MTB: 177.5mm
Single Speed 29" MTB: 180mm

I guess I've got nearly every length covered, though I have sometimes run 167.5mm and 170mm on the track for various events.


Why do you run such long cranks on the Single Speed MTB's ?
If the R-1 rule is broken, what happens to N+1?

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nimm
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Postby nimm » Wed Jul 02, 2008 12:54 am

172cm, 172.5mm crank.

This isn't by choice, that's just what my bike came with.
/ Giant OCR / Go Vegan /

Dunk
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Postby Dunk » Wed Jul 02, 2008 8:14 pm

mikesbytes wrote:
Dunk wrote:I'm 167cm;

Track Bike: 165mm
Road Fixie: 170mm
Road Bikes: 172.5mm
Mountain Bike: 175mm
Single Speed 26" MTB: 177.5mm
Single Speed 29" MTB: 180mm

I guess I've got nearly every length covered, though I have sometimes run 167.5mm and 170mm on the track for various events.


Why do you run such long cranks on the Single Speed MTB's ?


Leverage.

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