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Ortho pedals/knee pain/alternatives to crank length

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Ortho pedals/knee pain/alternatives to crank length

Old 11-20-21, 07:13 PM
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runner3344
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Ortho pedals/knee pain/alternatives to crank length

I have been told that for people like me with limited flexibility in a knee joint that a person can buy shorter crank arms or bolt on crank shorteners that will allow me to ride mountain bikes again.( Ortho pedals ?) Does anyone know anything about this ? Or have first hand knowledge ? I cannot bend my knee past the 90 degree mark and this makes it just about impossible to complete a circle while pedaling. Any help with this problem would be greatly appreciated. I tried just raising the seat but that didnt work.
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Old 11-20-21, 09:01 PM
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Well sure, shorter cranks will require you to bend your knees less. There are plenty of short crank options out there.

Just Google “150mm crankset” or “125mm Crankset” and a bunch of options come up.
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Old 11-20-21, 09:42 PM
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After my knee surgery I ditched any crank that was 175 for a 170 and the difference was noticeable, my racing bike is 172.5 and I notice that when I ride it, can feel a touch more stress in the knee. Track bike is 165 of course and that is really easy on the knee and probably what I should have switched most to. There are some decent 152mm crank options out there for mtb which will give a nice, easy circle to pedal.
https://www.srsuntour.us/collections...ucts/zeron-1-x
I put this on my daughter's mtb, little chunkier than I'd have liked for her but stiff and smooth for a good price. They also have doubles and triples.
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Old 11-22-21, 08:25 AM
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If both legs have the same range-of-motion restriction, shorter crank arms are a good option. 165mm arms are quite common and available from multiple manufacturers. Shorter than that, the options are more limited. TA offered arms down to 150mm, and BMX cranks go even shorter than that, but may require some modification for road use, depending on what rings and how many you intend to use. Mark Stonich at BikeSmithDesign has a crank-shortening service.

If one leg is shorter than the other, an orthopedic pedal is probably a better option. TA used to offer cage plates in different heights to accommodate different length legs, but there were intended for use with toeclips, which may not be what you want.



If you're using modern, clipless pedals, a spacer could be mounted between the cleat and the shoe. I'm not aware of any commercially available spacers, though. Sounds like a good project for a 3-d printer.

Last edited by JohnDThompson; 11-22-21 at 08:29 AM.
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Old 11-22-21, 10:04 AM
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Originally Posted by runner3344 View Post
I have been told that for people like me with limited flexibility in a knee joint that a person can buy shorter crank arms or bolt on crank shorteners that will allow me to ride mountain bikes again.( Ortho pedals ?) Does anyone know anything about this ? Or have first hand knowledge ? I cannot bend my knee past the 90 degree mark and this makes it just about impossible to complete a circle while pedaling. Any help with this problem would be greatly appreciated. I tried just raising the seat but that didnt work.

MnHPVA Guy customizes shorter cranks. This is his website:https://bikesmithdesign.com/Short_Cranks/index.html
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Old 11-23-21, 08:32 AM
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Can your knee problem be fixed? I have both knees replaced and I ride 175mm crank arms with a 72-73cm saddle height. Replacement knees must allow the leg to fully straighten, but the lower leg won't bend back nearly as far, so the top of the stroke is where a problem may occur. That's part of rehab - full travel bike pedaling ASAP.
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Old 11-23-21, 08:55 AM
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Just so you know, there's an Adaptive Cycling forum on BF, you might want to search there for info and/or start a thread there.

I don't know how many of the people who post there actually monitor General Cycling.
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Old 11-24-21, 09:26 AM
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I’ve now put five friends and acquaintances on 150mm cranks. So far it works every time. Two of those were because of flexibility issues. Four of five were very happy immediately -as in they were thrilled in the first thirty seconds of test ride. Number five needed a period of adjustment but would never go back. Trying them on my own bikes they work well enough, no particular problem or downside. Personally staying with full length out of long habit and because my very vintage bikes want very vintage cranks. Try to think of short cranks as something completely normal. They are. Cannot possibly be certain they would be the perfect solution for you. Definitely worth a try.

Use the same gears with the short cranks, no need to calculate or purchase anything different. When the crank gets 20mm shorter the saddle goes up 2 to 5mm. Unless you were already high.
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Old 11-26-21, 01:33 PM
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You might want to take a look at recumbent bikes as well.
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Old 11-27-21, 10:23 PM
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Don't forget pedal extenders/knee savers too, to help "widen your stance" so to speak.
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