Unequal leg length

[Ealingoldie]

Hi everyone,

I was crocked in Spain by a bendy bus & broke hip so now right leg 2cm shorter than left - Ideas about solutions to get me back on the bike before I die?

GO

 

[MartinC]

Hi everyone,

I was crocked in Spain by a bendy bus & broke hip so now right leg 2cm shorter than left - Ideas about solutions to get me back on the bike before I die?

GO

IIRC in the days before clipless pedals TA would make custom pedals with built up cages to compensate for unequal leg.

The ideal solution is to use cranks of different lengths because it will match the circle of motion to your leg length. This is possible with pick and mix cranksets (TA come to mind again, as do Middleburn and Highpath) but expensive. I would think (and others may have better advice) that you only need to compensate for part of the 2cm difference as your body will compensate to some degree itself. Many people have legs of unequal lengths anyway - an orthopeadic surgeon once told me that 5mm is quite common.

Putting a spacer (you'd have to make it yourself) between your shoe and cleat might be part of the solution too as may be putting an insole in one shoe.

The best solution may be a combination of all the approaches.

If you use flat pedals then building one up or choosing 2 pedals with different cage depths may be an option.

 

[jasonmccullum]

i had an accident when i was younger and my leg is 2.54cm shorter so i knwo how u feel


i got some 35mm bolts and bought 22mm spacers and it works brilliantly

cost me £2.54 in total

pm me and i will send you pictures and details of where i bought the bits

 

[ColinJ]

Putting a spacer (you'd have to make it yourself) between your shoe and cleat might be part of the solution too as may be putting an insole in one shoe.

That's what I did when I wore my Sidi shoes with Look pedals. I shimmed about half the discrepancy and it seemed to help. It was too much to try end make up the full difference, my foot started to rock on the pedal.

 

[ASC1951]

i had an accident when i was younger and my leg is 2.54cm shorter so i knwo how u feel

i got some 35mm bolts and bought 22mm spacers and it works brilliantly

I'm another mis-shape, according to my physio. 1cm, apparently enough to be worth doing something about, because it is starting to distort my posture.

Can your method work with clipless pedals, Jason, or would I have to put the spacers between the cleat and the shoe?

 

[jasonmccullum]

i put the spacer between the shoe and the cleat

makes it easier and more secure if someone lets me know how to add pictures i will post some on here

 

[ColinJ]

i put the spacer between the shoe and the cleat

makes it easier and more secure  if someone lets me know how to add pictures i will post some on here

If your pictures are hosted somewhere online like Flickr - just use the Insert Image icon above the post edit box (two to the right of the smiley face). Enter the URL of the image (http://mysite.com/myfolder/myfilename.jpg - that kind of thing)) in the popup box and then click Insert Image on the popup.

If the pictures are on your PC, attach them to your post using the Attachments facilty below the post edit box. Click the choose button and navigate to wherever your photograph is and click on it to get its name in the filename field, then click the Open button. Then click Attach This File below where you did all that

 

[ASC1951]

The ideal solution is to use cranks of different lengths because it will match the circle of motion to your leg length...

.. I would think (and others may have better advice) that you only need to compensate for part of the 2cm difference as your body will compensate to some degree itself.

I don't see how that can possibly work, Martin. OK, you are equalising the effective leg length for half the revolution but you are doubling it for the other half. If the discrepancy is already enough for someone to find it a problem, unequal length cranks are going to cripple him.

 

[Fiona N]

There's a whole lot of stuff on leg length discrepancy and how to 'treat' it on the cyclingnews.com website under fitness Q&A (search for LLD or leg length discrepancy). It's often pretty technical because of the caliber of both questioners and responders but well worth looking over the suggestions.

I think some expert advice is useful because the 'treatment' of LLD depends on where the discrepancy arises i.e. whether it's above or below the knee and whether it involves other shortcomings like hip or pelvic inflexibility or instability, knee problems, inwards or outwards tilt in the ankle during pedalling. If you're serious about your cycling I'd consider this issue carefully before making costly or potentially injurous adjustments.

 

[MartinC]

I don't see how that can possibly work, Martin. OK, you are equalising the effective leg length for half the revolution but you are doubling it for the other half. If the discrepancy is already enough for someone to find it a problem, unequal length cranks are going to cripple him.

ASC1951, apologies, but I'm not sure I understand the point you make. What I was trying to say was:

There are 2 leg lengths involved. If you use different crank lengths then you could theoretically get each leg (foot) to move in it's optimum circle. But. Optimum crank length depends on more things than just overall leg length - the proportions of thigh and lower leg and foot size matter too as does flexibility. In addition many people's bodies have already adapted to take account of some asymmetries. So just factoring a crank difference that matches the leg difference may not be the best or total solution.

As Fiona says there's lot's more erudite and knowlegeable information out there, I was just trying to give the OP a few pointers.

 

[ASC1951]

ASC1951, apologies, but I'm not sure I understand the point you make. What I was trying to say was:

..... If you use different crank lengths then you could theoretically get each leg (foot) to move in it's optimum circle. ....

Fair enough, My point was this, but I'm a paper shuffler, not a geometer, so I could be wrong...

Just looking at it theoretically, what you need to do is to reduce the pelvis-pedal distance for one leg. OK, by using a shorter crank on one side you can get the foot to move in its optimum circle, but the centre of that circle won't be correct. At the bottom of the stroke you will have compensated for the difference, but at the top of the stroke the shortfall will now have been doubled - if one leg is shorter by 1cm and you go from a 175 to a 165 on that side, the pedal at the top is now 2cm further away from equilibrium. What you need to do is to move the effective centre of the circle upwards; so because the pedal retains its orientation, the adjustment has to be made to the distance between the top of the pedal and the foot, NOT to the distance between the two ends of the crank.

 

[Ticktockmy]

Fair enough, My point was this, but I'm a paper shuffler, not a geometer, so I could be wrong...

Just looking at it theoretically, what you need to do is to reduce the pelvis-pedal distance for one leg. OK, by using a shorter crank on one side you can get the foot to move in its optimum circle, but the centre of that circle won't be correct. At the bottom of the stroke you will have compensated for the difference, but at the top of the stroke the shortfall will now have been doubled - if one leg is shorter by 1cm and you go from a 175 to a 165 on that side, the pedal at the top is now 2cm further away from equilibrium. What you need to do is to move the effective centre of the circle upwards; so because the pedal retains its orientation, the adjustment has to be made to the distance between the top of the pedal and the foot, NOT to the distance between the two ends of the crank.

Bloody hell, too much information, personally I would go to LBS measure up different pedals for heigth of pedal platform, and buy a set which gives your knackered leg the 2 cm hight you require.

 

[jasonmccullum]

i had an accident when i was younger and my leg is 2.54cm shorter so i knwo how u feel


i got some 35mm bolts and bought 22mm spacers and it works brilliantly

cost me £2.54 in total

pm me and i will send you pictures and details of where i bought the bits

 

[ASC1951]

Ah, thanks for those Jason. I normally use SPDs rather than Looks, but it should work just as well. Looks give you three point contact, which is more stable: OTOH I only need 1cm spacing, so the leverage on the bolts shouldn't be any greater.

I'll see what the biomechanical people at Leeds Carnegie tell me tomorrow. Probably "Take up tiddlywinks, you old fool."

 

[MartinC]

Fair enough, My point was this, but I'm a paper shuffler, not a geometer, so I could be wrong...

Just looking at it theoretically, what you need to do is to reduce the pelvis-pedal distance for one leg. OK, by using a shorter crank on one side you can get the foot to move in its optimum circle, but the centre of that circle won't be correct. At the bottom of the stroke you will have compensated for the difference, but at the top of the stroke the shortfall will now have been doubled - if one leg is shorter by 1cm and you go from a 175 to a 165 on that side, the pedal at the top is now 2cm further away from equilibrium. What you need to do is to move the effective centre of the circle upwards; so because the pedal retains its orientation, the adjustment has to be made to the distance between the top of the pedal and the foot, NOT to the distance between the two ends of the crank.

Ah, yes, understand your point. You're correct - the next question after you've compensated for the unequal leg length is to decide the optimum saddle height 'cos you can only have the BB and saddle one distance apart. I don't think there's any solution to this. One leg will have the saddle too low putting the knee joint through too big a range of movement under stress and for the other the saddle will be too high causing the pelvis to rock. I guess you'd have to work out the best balance for this by trial and error.

I have seen hinged cranks for cyclist with very limited movement in one leg or hip but I don't think the OP has such a difference that these would be relevant. If I get time I'll try and find a link to them.

Edit: http://www.hingedcrankarm.com/what_is_it.htm