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Adaptive Cycling: Handcycles, Amputee Adaptation, Visual Impairment, and Other Needs Have a need for adaptive equipment to ride to compensate for a disability or loss of limb or function? This area is for discussion among those of us in the cycling world that are coming back from traumatic circumstances and tell the world, "No, you are not going to beat me down!"

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Old 10-22-16, 05:42 PM   #1
kendall
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how to compensate for 11/16 to 3/4 leg discrempency?

Confusing I know, but recently had knee replacement surgery The Problem is that I have been 'bowlegged' since grade school, and when my knee was replaced they straightened my leg out. So the issue is that my left leg is roughly 11/16 to 3/4 inch longer than my right leg.

I use platform pedals, so would just adding a 'pad' to the right side work well? The change in measurement depends on when it's measured, in the morning the difference is greater

Last edited by kendall; 10-23-16 at 03:10 AM.
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Old 10-27-16, 09:52 PM   #2
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Add a set of pedal blocks for your shorter leg. the 1/16" shouldn't make any difference as perfect symmetry doesn't exist.
Do you already have shoes that compensate for your leg length? If so you should be able to ride without modifying the bike?
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Old 11-04-16, 02:06 PM   #3
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Thanks!

Sorry for late response, had a tree take my satellite dish out

Think you're right, shoes seem to work the best. I need to pick up a set for the bike, right now all I have that compensate are work boots, they work great, but are heavy and tall so restrict my ankles.

I tried taping some pads on the short side, they worked nice for shorter rides of 3-5 miles, but on longer runs it doesn't seem to work as well. With my boots, I could manage 20 miles, After putting the 1/4inch pads on I was pretty much done in after 10 if I pushed it.

So if anyone else needs this info, build up the leg, not the pedal.
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Old 11-04-16, 02:39 PM   #4
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Actually, you want half the leg discrepancy for your blocks. I have a 1/2" discrepancy and use 1/4" shims between my shoe soles and the cleats and a 1/2" heel lift for when I am not on the bike.

I have one pair of shoes that a cobbler put a 1/2" lift on. If you have a pair of preferred cycling shoes that a cobble can modify, you could have him put in a lift that is 3/4" under the heel but 3/8" under the ball of your foot.

About using half the leg discrepancy for cycling. When I was going through PT and had just learned of my discrepancy, I did the mental gymnastics and came up withthe half. TRied it and liked it. (1/4" aluminum plale bent to match the curve of the sole.) Showed it to my PT next visit, She said that was exactly what she would have ordered. Been using it now on all my cycling shoes for the two years. Love it. FOr the first time ever, I get to sit on-center on a bike. When I look down, I see right down teh center of the frame. Mind blowing! (This after 52 years of riding crooked.)

Ben
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Old 12-28-16, 01:03 PM   #5
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I assume you're asking because the discrepancy is causing you issues when riding.

My left leg, largely because of my teen growth, is a full inch shorter than the right. It's visible when I walk, looks like I'm walking half-on a curb, lol.

I use nothing to compensate for it, because it doesn't affect my riding.

I generally agree with the 'half the distance' advice, because any more can easily distort everything else you do. When I was fitted with orthopedics for bone spurs, the heels in the shoes were about 5/16" too tall; wearing them HALF A DAY put me off work for two days because it threw out my lower back.

The ultimate goal is comfort in daily activities; small changes reach that better.
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Old 06-19-17, 09:56 AM   #6
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If it was my leg issue I'd get a different length crank arm rather than add a shim.
At the bottom of the stroke your shorter leg is helped by the shim, but at the top of the stroke your short leg is forced higher, which may or may not be good for the replaced knee and your overall cadence and posture.
While crank length is grossly overlooked, and we still give a 175 crank arm length to 5'6" and 6'6" riders, it's still IMO worth looking at as an option.
If your left leg is shorter and you crankset is 175, it would be fairly easy to buy a 170 arm for the NDS.
Then all shoes work the same and pedal axis stability stays the same.
Other mitigating factors might make the switch impractical.
Just my two cents...
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Old 06-19-17, 12:17 PM   #7
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TA of france, used to make a pedal with removable plates of various heights..
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Old 06-25-17, 08:03 PM   #8
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Hostel Shop and Jenson USA both sell crank shorteners. These are meant for adapting rear seat on tandem for a child, and the smallest adjustment is 24mm shorter
https://hostelshoppe.com/CS-TAE-CRAN...ER-STD-174531/

It's possible that you may want pedal extender, to widen your stance on 1 or both sides.
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Old 10-24-17, 03:55 PM   #9
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Quote:
Originally Posted by kendall View Post
Confusing I know, but recently had knee replacement surgery The Problem is that I have been 'bowlegged' since grade school, and when my knee was replaced they straightened my leg out. So the issue is that my left leg is roughly 11/16 to 3/4 inch longer than my right leg.

I use platform pedals, so would just adding a 'pad' to the right side work well? The change in measurement depends on when it's measured, in the morning the difference is greater
Sorry, very late to this discussion, and you have surely figured something out by now. But I thought I would chime in in case others search for this.

I have done a lot of research and personal tinkering with this, as I have a 50mm leg length discrepancy.

But first I should ask whether you know for sure that the discrepancy is in the leg itself, and not an issue with your hips? I am not knowledgeable in addressing the latter, just enough to know that you often need to deal with it differently than the former.

Assuming it is the actual length of your leg bones....how you deal with the discrepancy depends somewhat on whether the discrepancy is above or below the knee. In my case, 35mm is above the knee, 15mm below the knee.

If the discrepancy is below the knee, the solution is pretty simple: just use an 11/16" - 3/4" lift or shim. All you need to do here is make the length between the pedals and your knees the same (or close).

The lift on a regular shoe is a pretty simple affair. If you want to use shoes with cycling cleats the modification is more involved (not as simple as people might think).

It can be more complicated if you have (as in my case) a large discrepancy is above the knee, because if you try to make up the difference with a shoe lift (or pedal shim) you end up making the pedal-knee distance greater on that leg, so you end up with it more deeply bent at the top of the pedal stroke. This gets complicated to explain, and every solution is a compromise. In my case I ended up with different crank lengths (5mm difference) and a 40mm shoe lift. It is not ideal, but it is the best solution I have tried (and I have tried MANY).

In your case, though, with it only being 3/4" discrepancy, I have the suspicion you'd be able to deal with this with a simple lift or shim. I would try going with the full amount (~3/4") and see how it feel at the top of the pedal stroke. If it feels off, try a smaller lift/shim.

Interested to hear how this went for you.
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