# Crank length for singlespeed



## Basil.B (5 Dec 2012)

What's the best length to get 165 or 170?


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## wanda2010 (5 Dec 2012)

Some people get 165s so there is no pedal strike.


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## GrasB (5 Dec 2012)

SS Freewheel? Then you want shorter to help increase your maximum cadence, 165mm is good, 160mm or even shorter is better
Fixed gear? Then I'd tend to go for longer cranks, maybe 175mm as you'll be able to spin faster due to the way that fixed gears work.


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## Pottsy (5 Dec 2012)

I think your leg length should be a factor too


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## GrasB (5 Dec 2012)

Femur length & flexibility of the tendons in your knees defines the *maximum* length of crank you can use. Going shorter that is rarely a problem. Within a wide range crank lengths you'll produce almost the same power for the same foot speed; 100rpm on 175mm cranks roughly to 113rpm on 155mm cranks. Though there will be a process of acclimatising to radically different crank lengths, it's more getting your muscle memory & coordination sorted. Say you jump from 175mm cranks to 155mm cranks, you'll be trying to push down beyond the end of the pedal travel.


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## smokeysmoo (5 Dec 2012)

My Fuji Feather is a 61cm frame but shipped with stock 165mm cranks. Although my geared bike has 175 mm cranks, and I'm 6' 5" it's absolutely fine. 

The only time I change them is when I have to fit 170mm cranks to make it track compliant for Manchester Velodrome


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## jim55 (5 Dec 2012)

id go shorter ,160 or 165 but not any more ,theres loadsa factors to determine your "correct"crank length ,but these pale into insignificance when faced with pedal strike when going round a corner and uv gota bank it over more than normal(too fast ,oncoming car/ped ),and 5mm can make the diff between you making it round nonchalontly ,,OR ,,pedal strike on the road ,you getting launched up in the air and ending up arse over tit in front of a potential oncoming car !!
get the shorter ones if u can


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## GrasB (5 Dec 2012)

2189282 said:


> Other way around. Shorter with fixed reduces likelihood of pedal strike


Pedal strike IME is a non-issue, thus you're looking at other factors for crank length.

EDIT: Just checked, about 30 degrees of lean on my fixed with 175mm cranks & 23-622 wheels.


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## GrasB (5 Dec 2012)

On the track the pedal strike issues at low speeds are caused by the steep banking of the track, thus shorter cranks are used along with higher BBs. Fixed road bikes tend to look to track bikes for inspiration & thus they also tend to run with short cranks.


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## GrumpyGregry (5 Dec 2012)

pedestrian refuges+filtering+fixed+long cranks=crunch


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## GrasB (5 Dec 2012)

GregCollins said:


> pedestrian refuges+filtering+fixed+long cranks=crunch


pedestrian refuges+filtering+fixed+long cranks+*bad riding skills*=crunch


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## GrumpyGregry (5 Dec 2012)

GrasB said:


> pedestrian refuges+filtering+fixed+long cranks+*bad riding skills*=crunch


compulsory in Cambridge?


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## GrasB (6 Dec 2012)

GregCollins said:


> compulsory in Cambridge?


Only for students, doubly so for language students.


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## Old Plodder (6 Dec 2012)

If you value your knees for use in later life, one fifth of your inside leg measurement; for any bike that you ride.


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## Dan B (6 Dec 2012)

Likelihood of pedal strike surely depends also on BB height, which seems to vary a lot depending on fashion. The BB on my early 80s 531 frame is so low that on 48x16 the top line of the chain slopes upwards from chainring to sprocket


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## Christopher (6 Dec 2012)

Interesting, dan b! I have a 1983 Dawes converted to fixed. It has 170mm cranks and has a slight pedal strike problem - I will measure the BB height on it - be interesting to see how it compares with modern bikes.

Edit: Measured last night: 267mm ! The modern bike I have has 280mm BB height, looks like Santa will have to getting some 165mm cranks pour moi...


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## Boris Bajic (6 Dec 2012)

Dan B said:


> Likelihood of pedal strike surely depends also on BB height, which seems to vary a lot depending on fashion. The BB on my early 80s 531 frame is so low that on 48x16 the top line of the chain slopes upwards from chainring to sprocket


 
That's not a low BB, that's rear drop-outs mounted too high!

Do not doubt me for a moment. I once knew a bloke who had sat next to an expert on a train.


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## Basil.B (7 Dec 2012)

Ta for the replies. I'm 5' 8" with a 31" inside leg so I shall probably go for a 170 mm crank.


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## dave r (13 Dec 2012)

I'm 5'6" with a 29 inch leg, my fixed has 165 cranks, the short cranks suit my short legs and make spinning up on a descent much easier. You need to work out what crank length suits you and what your comfortable with, 170 mm cranks are a good starting point, spend some time on them and work out whether they are right or not and decide whether you want to stay with them or go higher or lower.


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## Rohloff_Brompton_Rider (13 Dec 2012)

Personally, I use 10 mm shorter cranks on my fixed gear. The reason I do this is too give me more of a chance of not being launched from pedal strike on curb stones. It is only a philosophical thinking and not even remotely evidence based.


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## Basil.B (14 Dec 2012)

Won't a 170 mm crank give you more leverage for going up the hills?


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