Shims and Bolts

[Glasgow44]

Hi there

I recently had a bike fit because of a leg length discrepancy; my right leg is shorter than my left due to a previous ski accident. Anyway, the bike fitter has suggested a 12mm shim stack for my right leg and 20-22mm screws. He did mention at company called Form who does these and I have emailed them.

Has anyone else had to buy shims and longer screws like this? if so, can you recommend where? I use SPD-SL pedals.

Thanks in advance

 

[Ajax Bay]

Form: https://www.form-bikefitting.com/leg-length-shims/leg-length-shim-3-hole-universal-modular-bulk
So four 3mm shims, stacked.
Screws might be best from non-bike source: https://www.accu.co.uk/flanged-button-screws/155411-SSBF-M5-22-A2-BL
Be sure to check that M5 is correct.
Pack of 5 for £1.78 - https://www.westfieldfasteners.co.u...et_Head_Button_Flange_Screw_A2_Stainless.html
The flanges on those are all 11.6mm whereas the 'normal' ones supplied with cleats are 14mm; nevertheless they will still secure OK.
I wonder if an alternative approach would be to choose a longer LH crank.

 

[DCLane]

+1 to @Ajax Bay 's suggestion. A longer LH crank might solve the problem quicker and easier.

 

[Profpointy]

+1 to @Ajax Bay 's suggestion. A longer LH crank might solve the problem quicker and easier.

A spacer or shim makes the crank effectively shorter at the bottom of the revolution but longer at the top. This is likely not quite what you are trying to do

 

[I like Skol]

The shim solution sounds ideal to me, it effectively raises the bottom bracket height for that leg. Using odd length cranks is an awful compromise because it does nothing to address the saddle to bottom bracket distance.

 

[T4tomo]

The shim solution sounds ideal to me, it effectively raises the bottom bracket height for that leg. Using odd length cranks is an awful compromise because it does nothing to address the saddle to bottom bracket distance.

exactly, longer crank gives a bigger circle around the same centre, a shim gives you same sized circle around a point 12mm higher.

 

[Ajax Bay]

Well if the OP sticks with their current RH crank/spider then the saddle can be dropped a centimetre ("address[ing] the saddle to bottom bracket distance") and the shorter leg is thus catered for. Their longer leg is 'long enough' to prefer a longer crank, at the top and the bottom of the stroke.
Does depend on the current cranks being 170 or less.
But I'm not a bike fitter. And I only floated it as an alternative. Depending on the crankset, the shims plus sensibly procured screws (get 5/6, 2/3 spare) look like being cheaper.
I guess with shims it'd be easier when walking (albeit on SPD-SLs!) and the shorter shoe is 'stacked'.
I used to have one leg about 5mm shorter than the other: not any more! The surgeon sorted that integrated with a THR.
OP should consider a heel wedge in their everyday shoes (if not already) as that sort of length difference is liable to result in greater than normal leg joint issues idc (but I'm not a ortho).

 

[wonderloaf]

Due to my right leg being about 12mm shorter than my left I've been using Form SPD shim(s) at 5mm (the maximum) for the last year or so, this has made me feel much more balanced and symmetrical in the saddle.
This video might give some useful info, its primarily aimed at SPD users but guess it's also applicable to SPD-SL as well:

View: https://www.youtube.com/watch?v=IS0gj0ig-jc&list=PLLDtighiMfmBeeJaSQlUZla1EPOZ2yrOt&index=2