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Crank length

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Crank length

Old 07-14-20, 11:56 AM
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LeftyS7
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Question Crank length

One of my legs is a 1/2" longer than the other. Should I get a crank that is 1/2" longer for that leg?
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Old 07-14-20, 01:43 PM
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There is different opinion on that. Seems one way to handle it, but there might be better ways. I think some that actually ride with the same issue commented in this thread. Maybe they'll be back to give you some thoughts on the subject.

XRays show leg length discrepancy

If you use the same crank lengths then I'd think you'd want to size the saddle height by the shorter leg unless something else is done to correct that difference.

Last edited by Iride01; 07-14-20 at 01:46 PM.
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Old 07-14-20, 01:56 PM
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That's what I've done.
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Old 07-14-20, 02:14 PM
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it depends on where the leg length difference is, and if it is functional or skeletal.
i have a 6mm leg length discrepancy that is pretty evenly distributed between my femur and tibia, and a combination of shim between cleat and shoe, and slightly different fore/aft cleat placement seems to do the trick.
adjusting your cleat in that way would seem to be the least expensive and easily modified method.
once you figure out what works, you could see if it translates to a crankarm length change instead.
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Old 07-14-20, 02:26 PM
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Thanks, I don't use cleats.

I've never measured femur and tibia lengths, I'll have to do that.
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Old 07-14-20, 02:50 PM
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Smile

2.. ways to do it. A) build up the pedal on one side, or B) shorter crank on that side ( buying different arm length on the left would be cheaper)

of course B foot motion is circular A is a bit of a vertical Oval Perhaps a mix would work ?

Sports orthopedist would be a better resource than us, here...



{but the cost is free, opinoins are of equal value..


/..

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Old 07-31-20, 12:16 PM
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after thinking about this issue a bit more, i think you may not have considered the all the effects of a different length crankarm...
geometrically speaking, a shorter crankarm would result in a smaller diameter circle of foot travel for that side, which means you would be simulating a leg that is shorter at the bottom of the pedal stroke, but longer at the top of the pedal stroke. (and a mixture of the two at other crank angles)
what i think you are looking for (on the short leg side) is a method that takes the existing diameter circle of foot travel and offsets it only upward, simulating a leg that is shorter at the bottom of the pedal stroke, and shorter at the top of the pedal stroke.
this is why building up the pedal on the short leg side is the only simple/effective solution (barring use of cleats)
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