Shimano FC-MT8120-1 XT Crank Arms
Shimano developed the XT M8100 groupset to follow the top-level XTR M9100, with what used to be called XC Race and XC Trail versions. While the names were dropped the thought process remains, with the MT8100-1 weighing less and having a narrower Q-factor than the MT8120-1 crank model. The 12-speed 1x drivetrain option includes considerable new engineering and development, with the crankarms getting an entirely new construction process to accommodate the new 1x12-speed direct mount chainring system. In the process the hollow-forged anodized aluminum MT8120-1 crankarms were made stiffer, stronger and now have a 178mm Q-factor. A 55mm chainline is the result of that outboard movement. The 24mm Hollowtech II steel crank arm spindle remains the same, so the MT800 external bearing threaded cups work with 68/73mm bottom bracket shells, and the PressFit option is still the MT800-PA. The combination of proven technology and construction with new engineering and requirements is pure Shimano excellence.
The biggest change for the 1x12-speed set-up is the direct mount spline system. The wider, stiffer CRM chainring design has great benefits with wide ranging 12-speed cassettes. The driveside MT8120-1 crank arm had to be re-engineered for the direct mount. Shimano decided on a spline set-up that is functionally similar to their Center Lock disc rotor version. As in that case, a notched lockring is used to fasten the ring to the spline mount. The Shimano TL-FC 41 tool is needed to install this lockring. Shimano provides the tool with the early release boxed crankarm sets, and it is available separately as well. When tightened the system is incredibly secure, yet takes just seconds to install or remove when the crankarm is removed from the bike.
The CRM85 chainring of your choice is sold separately, and is available in 28, 30, 32, 34, or 36T options. Installation of the crankarms is the same as nearly all Hollowtech II spindle models, with a left side pre-load fixing bolt and two offset pinch bolts to affix the arm to the spindle.
- XT 12-speed crankarm set for aggressive trail, w/ direct mount system for 1x chainring
- Wider Q-factor and chainline than MT8100-1 version
- Entirely new construction, using direct mount spline ring mount
- Rigid and lightweight, but resilient design for aggressive trail riding
- Hollow-forged anodized aluminum crankarms maximize power transfer, limit weight
- Hollowtech II BB spindle- 24mm for external MT800 or PressFit MT800-PA BB's
- Stout steel spindle is plated for extreme corrosion resistance
- For 68/73mm bottom bracket shells
- Compatible chain: HG 12-speed (CN-M8100, CN-M9100)
- Q-Factor: 178mm
- Chainline: 55 mm
- O.L.D. 148mm
- Requires CRM85 XT direct mount chainring (28-36T) sold separately
- Crankarm fixing bolt,, spacers, Direct Mount lockring, TL-FC41 tool included
- Finish: XT Series Black
- Options: 165, 170, 175 mm
- Weight: 628 grams (w/ 32T ring- not included)