crank lenghts for leg length difference

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crank lenghts for leg length difference

Postby ed4016 » Fri Mar 15, 2013 15:08 pm

ok lads just wonder does anyone know if it is possible to get a crank with 172.5 and 175 on the right the reason behind this is that i suffer with a mild case of cerebral palsy and have 1 leg longer than the other. Now this might not be possible to get but just said id ask.


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Re: crank lenghts for leg length difference

Postby adambutterwick » Fri Mar 15, 2013 15:36 pm

You could get a set of cranks with 175mm arms and then a get a 172.5mm replacement left arm, depends on the model. Here's a quick google: ... 76&bih=706

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Re: crank lenghts for leg length difference

Postby styxd » Fri Mar 15, 2013 15:41 pm

Have a look on some bike fitting websites, Steve Hoggs is good. I think generally, the way to correct different length legs is with shims/spacers under your cleats.

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Re: crank lenghts for leg length difference

Postby sungod » Fri Mar 15, 2013 18:24 pm

normally a shim would be added to the shoe - to increase effective leg length

if you were to, for instance, decrease crank length on one side, it would put the foot higher at the bottom of the stroke, but lower at the top of the stroke, which is a completely different to what the shim would do

really, i'd go and see a bike fitter who is able* to assess you and make the correct adjustments to cleats/shoes/whatever, the best solution may involve more than simply adding a shim

*not all will be able to do it, don't be afraid to ask before commiting to the service, if you post which area you are in some others may be able to recommend places to try
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Re: crank lenghts for leg length difference

Postby wishitwasallflat » Sat Mar 16, 2013 19:53 pm

I have a leg lenght discrepancy too due to having had major surgery on my leg as a child - I solved the problems with a shim under the cleat. It was easy for me cause I use Speedplays and you can buy a shim kit that fits easily with the adaptor plate for the cleat. As above I would reccomend correcting this with a shim not different cranks.

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Re: crank lenghts for leg length difference

Postby mitchgixer6 » Sat Mar 16, 2013 19:58 pm

Yes a shim is the way to go with this. I have one leg 3mm shorter than the other, and a 3mm shim under the cleat on the short leg has made a big difference for me. Just search online you should be able to get one for about £10.

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Re: crank lenghts for leg length difference

Postby surfgod » Sun Mar 31, 2013 14:06 pm

I would avoid the short crank option for now...I tried it once as my left leg is 13mm shorter than my right..The cleat spacer is usually the best option, but you need to be conservative when making changes to your pedal stroke and bike position, or you can create more problems than you solve. Conventional wisdom among bike fitters suggests that only half a leg length disprepancy should be corrected with a shim, your body is usually capable of compensating for the other half.

The photo below is my current setup- I use a speedplay leg length compensator plate from Steve Hogg's bike fitting website. It's just an 8mm thick version of a speedplay fore-aft adaptor plate..On its own it gives me a 5mm lift. the standard speedplay baseplates being 3mm thick .


Alternatively you could just buy two or even three packs of speedplay fore-aft aluminum adaptor plates. These are much stronger than the silly plastic baseplates speedplay supply with their pedals. And simply stack them to your required height...use longer screws from your local hardware store to secure the stack to your shoes. You will have to cut the screws to the required length, otherwise they will protrude through the insole of your cycling shoes... Ouch!!!!...

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Re: crank lenghts for leg length difference

Postby Monty Dog » Sun Mar 31, 2013 15:13 pm

If you have a limited range of movement then shorter crank lengths is better - a shim doesn't actually reduce the arc, it just offsets it a little.
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