With all the hullabaloo surrounding the XTR 2x10, not enough attention is being paid to what may be the most advanced and highest tech triple mountain crankset the industry has been made privy to.
Shimano engineers have taken some residual technology from the M970 series, borrowed some ideas from Dura-Ace 7900, like the 3D outer ring and come up with some fresh ideas to bring us the M980 crankset.
The cranks arms are the super stiff, cold forged HollowTech II design mounted to a one-piece steel spindle. Like the arms, the 3D outer ring is cold forged and hollow as well, receiving similar cosmetic anodization and polishings. Hollowing out the outer ring and giving it some depth makes it so stiff, there is virtually no deflection while shifting. The middle ring is a hybrid carbon/titanium composition for durability and light weight, while the inner most ring is steel. The one design feature all of these rings share is HG-X profiling. This special tooth shape combined with tighter Dyna-Sys gear ratios brings us the best shifting we have experienced in a mountain triple crankset.
Shimano includes an XTR bottom bracket with shims to work with 68mm or 73mm bottom bracket shells.