Advice on new Chainrings, please

[Asa Post]

I currently have Shimano 5700 triple chainrings [50, 39, 30] on my road bike. Due to an accident, my right thigh is now about 18mm (difficult to measure accurately) shorter than my left. This causes a number of problems when pedaling. I tried a wedge between the shoe and the cleat, and while it helped at the bottom of the pedal stroke it made things worse at the top as I had to lift my knee higher, and the reduced range of movement in my hip makes that difficult and painful.
I have been advised that a shorter crank on the right side would probably help, and that the best length would be 160mm.
I've thought about trying to get a right crank separately, but my chainrings will soon need replacing anyway so I might as well change them now. The plan is to keep the existing left crank and fit it to the new setup.

Shimano don't make cranks shorter than 165mm, so I can't do a straight swap. I'm considering a Spa Cycles XD-2 Touring Triple Chainset with Stronglight Zicral Rings instead. Custom chainring combinations are available, so I could have the same-sized chainrings as at present, which would let me keep the existing front derailleur.
Or, I could have smaller rings, but I've read on the CTC forum that I'd need a new derailleur that could handle a 10-tooth difference between the large and middle rings because the existing one needs an 11-tooth difference. I don't really want to change the front mech, unless it's unavoidable.
In either case, I think I'll need a new bottom bracket as the existing Hollowtech II won't be compatible.

Will this work? What problems am I likely to have?
Are there any alternative setups I could consider, or other solutions I could try?

 

[Sharky]

Try http://www.highpath.net . They can re drill existing cranks to a shorter length. Have had two sets re drilled and had no problems. They might have other suggestions.

Good luck keith

 

[Sittingduck]

I was going to sugegst something similar to the above. Somebody at my club had an injury that required a crank to be made shorter and he told me about having a crank drilled to make a new hole.

 

[cyberknight]

You can get crank shortners but they do move the pedal out .......
http://www.sjscycles.co.uk/thorn-crank-shorteners-prod239/?src=froogle

 

[Asa Post]

@Sharky and @cyberknight
Thanks for the links.
I've had a look at Highpath, and the minimum reduction in crank length is 20mm (for a redrilled crank) or 27mm (if a crank shortener is fitted). Either option would make the crank too short. Also my existing cranks are Hollowtech II and this site says they can't be redrilled anyway.
The Thorn shortener reduces the length by at least 16mm, which again is too much and I can't see how it would fit to the existing right-side crank.

I can't find a way of adjusting the existing crankset, so I think I'll have to go with my original suggestion.

 

[Sharky]

No probs, I had mine re drilled down to 150mm and since bought another set which are 145mm. Both very comfortable and feel good and wouldn't go back to conventional cranks now.

Good luck
Keith

 

[jowwy]

No probs, I had mine re drilled down to 150mm and since bought another set which are 145mm. Both very comfortable and feel good and wouldn't go back to conventional cranks now.

Good luck
Keith

How tall are you sharky? And why did you go to shorter cranks?

 

[Sharky]

How tall are you sharky? And why did you go to shorter cranks?

Normal height etc 5'9"
Switched to the shorter cranks after a lot of reading about efficiencies, better riding (aero) position, opens up the hip angle, so legs don't keep hitting my generous stomach muscles, reduces knee strain and stay in the saddle for longer when climbing.

Cheers Keith

 

[MichaelW2]

Is Highpath Engineering still in business?

Odd sized cranks are a good solution to your problem.
Stronglight (SPA) are a solid piece of kit, Zircal rings are good. The teeth profiling and pins may not be as finely tuned as Shimano so shifting may not be so quick.
You will need a square taper 170mm on the other size. You should be able to pick one up new as an oddment/parts bin special or used.
Specialities-TA and Middleburn are good for crank oddities if you have a heavy wallet and wish to travel lighter.

 

[jowwy]

Normal height etc 5'9"
Switched to the shorter cranks after a lot of reading about efficiencies, better riding (aero) position, opens up the hip angle, so legs don't keep hitting my generous stomach muscles, reduces knee strain and stay in the saddle for longer when climbing.

Cheers Keith

Ive just got 170 cranks for my new Ti build, down from 175........maybe i should have gone a little shorter, but will see how they feel

 

[Asa Post]

Is Highpath Engineering still in business?

The website says that someone has agreed to take over the business, but will not be making some components that were previously available. I don't know if he is actually trading at the moment.

Odd sized cranks are a good solution to your problem.
Stronglight (SPA) are a solid piece of kit, Zircal rings are good. The teeth profiling and pins may not be as finely tuned as Shimano so shifting may not be so quick.
You will need a square taper 170mm on the other size. You should be able to pick one up new as an oddment/parts bin special or used.
Specialities-TA and Middleburn are good for crank oddities if you have a heavy wallet and wish to travel lighter.

Thanks for the encouragement. I've emailed Spa Cycles to see if they can do what I want. I asked if they would supply odd cranks, but I'm not holding my breath on that one.