xfimpg

Hi

I'm resolving a leg-length discrepancy issue where I need 5mm difference between cranks.

The stock crankset on my Giant is a Deore LX (M590) 175mm, and I need a left crank arm of 2.5mm shorter that will give me 5mm in all (counting circumference). The only product in a 172.5 that I found is the Shimano XTR crankset.

Out of curiousity I tried a Shimano 105 left arm because it's Hollowtech II as well, but the arm socket isn't deep enough and therefore the arm can't be screwed in.

I called Shimano and they haven't run that type of compatibility test and suggested that I visit an LBS and visually inspect myself.

I've tried the local bike shops but none of them have any XTR cranks in stock that I can compare with a Deore crank.

Can anyone advise if they've done this before or know if it's possible to mate a Deore LX with an XTR crank?

Thanks in advance
Michael

EDIT: I also need to take the offset into consideration when mating these two together.

Svr

The M970 XTR crank won't fit due to the interface between the spindle. Unsure about the M960.

I've always been told that installing spacers beneath the cleat was a better way to deal with a leg length discrepency.

xfimpg

Yes, that's true. I did make this modification on my roadie, but using Look Kea cleats it's possible.
With Mtb cleats (I use Time Atac Aliums), it's not possible to put a spacer between cleat and shoe.

ed 

Why not? Can't you just buy longer screws?

xfimpg

It's not the screws that are too short, it's the thickness of the 105 arm itself where you attach it to the BB. Because it's thinner than the Deore, the attachment coming from the right arm exceeds the left arm (it sticks out) so you can't screw the cap in.

ed 

I'm talking about the cleats, phart

xfimpg

LOL ok, gotcha!
Even with longer screws it doesnt work because the cleats need to be solid against the bottom of the shoe to engage the pedal. With spacers and longer screws, the cleat doesnt engage.

Dilberto

I believe the XTR M960 works. They come in 170mm, 172.5mm and 175mm. The best crankset Shimano ever made...despite the odd, 146bcd big ring.

xfimpg

Thanks
Now I just have to find a left 172.5 somewhere!

xfimpg

I received by order an XTR M960 left crank arm and tried mating it with a Deore LX M560 right arm and they are NOT compatible, even if they are both Hollowtech II.