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One leg long, one short, need new cranks

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One leg long, one short, need new cranks

Old 09-06-20, 12:42 PM
  #1  
hsuBM
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One leg long, one short, need new cranks

tldr: I will be buying a set of silver 165mm Sugino 75’s from my LBS annnnd...

I’m posting this thread in hopes of someone reading who, themselves or someone they know, has a long right leg and a shorter left leg and would be into buying a 170-175mm silver set to swap the NDS/left side with the one from the 165mm set which I am about to buy.

A 172.5 on the left would probably be about perfect for me, FWIW.

———


Due to a good ole femur shatter a handful of years ago, my right leg is 1.5cm shorter than my left. An nice ossification has developed in that leg’s flexor pack and the whole area is getting problematic.

Retrogression is currently out of stock and my surgeon & PT lady are telling me to get staggered cranks ASAP or start taking the car to work. I hate driving in this town and I really don’t want to buy two sets of cranks and wait forever to sell the ones that’re useless to me.



thanks in advance, folks

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Old 09-06-20, 08:42 PM
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Originally Posted by hsuBM
tldr: I will be buying a set of silver 165mm Sugino 75’s from my LBS annnnd...

I’m posting this thread in hopes of someone reading who, themselves or someone they know, has a long right leg and a shorter left leg and would be into buying a 170-175mm silver set to swap the NDS/left side with the one from the 165mm set which I am about to buy.

A 172.5 on the left would probably be about perfect for me, FWIW.

———


Due to a good ole femur shatter a handful of years ago, my right leg is 1.5cm shorter than my left. An nice ossification has developed in that leg’s flexor pack and the whole area is getting problematic.

Retrogression is currently out of stock and my surgeon & PT lady are telling me to get staggered cranks ASAP or start taking the car to work. I hate driving in this town and I really don’t want to buy two sets of cranks and wait forever to sell the ones that’re useless to me.



thanks in advance, folks
If you have platform pedals, have someone with 3D printer create something to bolt onto your pedal.
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Old 09-06-20, 09:07 PM
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Could you use a generic 172.5 on the left side while searching out a proper Sugino left in the size you need? I saw this - https://www.tracksupermarket.com/cra...crank-arm.html - but that’s a lot of cabbage for just a left crank.
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Old 09-06-20, 09:11 PM
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Originally Posted by hsuBM
tldr: I will be buying a set of silver 165mm Sugino 75’s from my LBS annnnd...

I’m posting this thread in hopes of someone reading who, themselves or someone they know, has a long right leg and a shorter left leg and would be into buying a 170-175mm silver set to swap the NDS/left side with the one from the 165mm set which I am about to buy.

A 172.5 on the left would probably be about perfect for me, FWIW.

———


Due to a good ole femur shatter a handful of years ago, my right leg is 1.5cm shorter than my left. An nice ossification has developed in that leg’s flexor pack and the whole area is getting problematic.

Retrogression is currently out of stock and my surgeon & PT lady are telling me to get staggered cranks ASAP or start taking the car to work. I hate driving in this town and I really don’t want to buy two sets of cranks and wait forever to sell the ones that’re useless to me.



thanks in advance, folks
have you tried sending an email to the manufacturer to see if they can help you out?
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Old 09-06-20, 09:35 PM
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I have the opposite issue, My right leg is shorter by 12 mm. I wear a 12 mm lift under my right heel in all my street shoes and the biggest lift that works with my cycling shoes. Under the ball of my foot I shimmed put the cleat with 6 mm (1/4" aluminum plate. (Bending it to fit the shoe curve was not easy!)

The shimmed shoe works really, really well! Bike feels completely "right". For the first time ever, I look down right through the center of the bike.

Don't go with unequal cranks. Shim your cleats (if you ride with them) or put a lift under your foot of 1/2 the leg length difference. (And more under the heel to the full difference if the shoe still works.)

The lift can be an insole or just as effective, additional thickness to the sole. I got the diagnosis and recommendations from cycle Oregon's PT. Life changing. (My legs are a QC issue. Since I never had the chance to use anything else I was clueless. Went to the PT for entirely different issues. First 5 minutes she had me walk the room away from her and back. "Your right leg's shorter." Sent me home with the 12 mm lifts, same as the difference in leg length, to put in all my shoes. (Shoes are different so I use different kinds for different shoes but all 12 mm. Had 2 re-soled.)

That was 10 years ago. I now take standing straight and sitting straight on the bike for granted, Until the lifts, it had never happened. 5 decades of crooked. (I ride 175 Sugino 75s but 1) they have 20k miles on them and 2) you aren't prying them (or even just one of them) from my cold dead hands. And I will never go with unequal cranks, at least not for this issue.)

Ben
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Old 09-06-20, 10:04 PM
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I just thought about the fact that it is your femur that is shorter. For, it is roughly spit between femur and tibia.

So, say you have a 40.5 and 42.0 cm femurs. I was going to run the calcs. pulled out paper and started sketching then realized Ii am hammered from a hard ride and this is beyond me tonight! I'll give it a try tomorrow.

Ben
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Old 09-06-20, 10:28 PM
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I would think a short femur would do better with a short crank than a short tibia.

But, as mentioned, the thicker pedals, some lift in the shoes, etc, could also potentially help.

I think I've read that the experience with other cyclists is that somewhere around 50% correction works well. So, for a 1.5cm leg length difference, you really only need to correct the length by about 0.75cm. And, adjusting the crank length is by radius, so even less than that.

So, 165/170 would be 5mm difference in radius and 10mm in diameter, and would probably be an adequate change. Especially if you add in a little extra lift with the sole, pedal, etc.

or 170/175mm, etc.

If you're buying basic square taper cranks, your local bike coop should have piles of them (if they are open). And, they don't have to exactly match. Most square taper cranks have the square on the diagonal, but worth checking. And, make sure the Q-factor is close.

At least using used or co-op cranks, you can test out your configuration before you dump in a lot of change.
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Old 09-07-20, 12:44 PM
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Rusty- I’ve gone generic/sub-$200 enough times that I’ve learned my lesson. My multiple unbrandeds, my somas, and now my IRD’s have all bent way more after small single tumbles than my ‘84 SR “Signature”’s did in the rather big wreck + a ton of small prior tumbles. Plus, all of the cheapos had significant heel-wear after under 1k miles whereas the SR’s have over 30k and only light surface marks. The heel-wear on the IRD Campy lookalikes is embarrassing- I’m glad that I bent them this summer and so so sad that I spent more than $40 on them.



Also done with used gear. Completely done. I’m not spending over $0.30 on cranks whose crash history is unknown. I’m not 20 anymore and snapping a used crank wouldn’t be a tenth as funny as it used to be (“whoah check out how strongs I is! Yeah, it probably had a hairline fracture before I bolted it on.”)



I have already spent at least $2k on cranks alone in the last decade (forget about all of the wheelsets, framesets, saddles, bars... Jesus, I’ve probably put in enough cash in this hobby/MoT in the last 20 years that, had I saved it, I could be buying a spanking new BMW M2 or a used 991 with cash), $300 more ain’t gonna hurt.





Regarding shims vs staggered cranks, as mentioned in the OP, I discussed this with an Orthopedic Surgeon of 20 years and a sports Physical Therapist of 15 years. Both agreed that 1) shimming/stacking insoles would only be worthwhile if it were a t/fibia difference 2) 165+175 is better than 165+165 or 175+175, and 165+172.5/167.5+175 is best- as mentioned- due to rotational diameter.



Because of the tendency of most LBS’ distributors to only stock some sizes/drillings/etc., I assume I’m not going to be able to get 167.5s and Person with a Long Right Leg won’t be able to get 172.5s, I’m in a temporary theoretical compromise of 165&170/175 until I chat with my LBS guy.



I am going to fire off an email to Sugino to see if they can be of any assistance, but since RG won’t despite appearing to physically be able to, I’m really not going to bother to cross my fingers on that.
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Old 09-07-20, 06:44 PM
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Unequal length crank arms won't do it. In order to accommodate the shorter leg, the longer leg will be sub-optimal. And vice-versa.

TA pedals had removable cage plates that could be had in different heights to accommodate unequal leg lengths. They've been out of production for years, and while they do show up, they tend to be pretty expensive (they're darned nice pedals, regardless of whether you need the orthopedic cage plates.

Specialites T.A. - pedals & cleats

If you use clipless pedals, you could fabricate a spacer to go under the cleat for the shorter leg. Sounds like a job for a 3-d printer, as @jay4usc suggested above.
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Old 09-08-20, 04:21 AM
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Originally Posted by JohnDThompson
Unequal length crank arms won't do it. In order to accommodate the shorter leg, the longer leg will be sub-optimal. And vice-versa.

TA pedals had removable cage plates that could be had in different heights to accommodate unequal leg lengths. They've been out of production for years, and while they do show up, they tend to be pretty expensive (they're darned nice pedals, regardless of whether you need the orthopedic cage plates.

Specialites T.A. - pedals & cleats

If you use clipless pedals, you could fabricate a spacer to go under the cleat for the shorter leg. Sounds like a job for a 3-d printer, as @jay4usc suggested above.
what I got when I clicked your link, herr doktor:

I will take your highly qualified medical advice into very serious consideration. Thank you for your input.

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Old 09-08-20, 06:04 AM
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Eddy Merckx had a similar problem after a crash left him with one leg longer than the other. First he tried shimming the short leg. Then he half shimmed the short leg - pushed the long side into the shoe and pulled back on the short side. Probably worked well with leather shoes. Davis Phinney was coached by Merckx and he had a naturaly short leg. He used Merckxs method of pushing the long side deep into its shoe and pushing back hard on the short. This worked best for them both.

Pro cyclists do not shim and wedge bike shoes EVER. They all use custom orthotics
British cycling and Sky cycling team were strongly opposed to this because it causes way more problems than it solves.
Ignor the idiots who pass themselves off as pro bike fitters and the clowns working in LBS. See a podiatrist for a proper assessment. Get yourself a pair of custom made orthotics. The only way to tell how much one leg is longer is by an MRI. Any other way is BS.
Normally people are able to naturally adjust to a leg difference of 6mm without any adjustment.

My advice if you are not racing is to find some of the old style cycling leather shoes. These are often sold online to the old timers - "STEEL IS REAL"
Push long side in deep and pull back hard the short side. Now v important adjust the seat forward/back position - set the long leg side knee "slightly ahead" of Knee over ball joint at 3 oclock. AND short side knee "slightly behind" knee over ball joint at 3 oclock. If you are not racing take this from in front of the knee - not middle of knee. This will give you a bit more of knee protection.
If you want to race follow a sports podiatrist advice and get a custom orthotic. If you cannot afford this go to a chemist discount store and buy a ready made :
Scholl ORTHAHEEL" ready made insole. I use these and they are the best thing I have ever bough for cycling.
Once again wave goodbye to anyone who tells you to shim or wedge a cycling shoe.
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Old 09-08-20, 12:39 PM
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Originally Posted by rymz
pushed the long side into the shoe and pulled back on the short side. ... He used Merckxs method of pushing the long side deep into its shoe and pushing back hard on the short.
a bit unclear... I think you meant “push the long side’s foot” and “pull the short side’s foot”, and that totally can be accomplished with adjusting one of my SPD cleats which would then alter where the pedal spindle is relative to the ball of that foot.

King Merckx’s quoted method appears to balance net leg angles in the scenario of unmatched femur lengths when either crank is in the middle of its downstroke and upstroke but still neglects the difference of net leg angles from the lower end of the downstroke through BDC into the upstroke.

If such a compromise worked for big Ed, that’s pretty cool, and I feel bad for him having been stuck with caged pedals. What a pain.

For anyone who reads this anytime deep in the future and their trusted medical professionals are giving them advice that contradicts what the Internet Wizards have to say, and Retrogression happens to be out of stock on individual cranks that might cost more than two pizzas but still cost way less than many people spend on pizza in a year, Yuki Iwai at Sugino got back to me immediately and was very courteous and helpful.

Eat pizza, ride hard, Best wishes.

Last edited by hsuBM; 09-08-20 at 01:06 PM.
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