The Shimano Deore XT FC-M8120-1 is a 12-speed MTB crankset built for trail and enduro riders who demand reliable, lightweight power transfer. Using Shimano's HOLLOWTECH II technology and a hollow forged crank arm construction, it delivers outstanding stiffness-to-weight performance with a 55mm chainline optimised for Boost hub spacing.

Highlights

• HOLLOWTECH II technology: Shimano's hollow forged crank arms provide an exceptional balance of stiffness, strength, and low weight for confident power transfer on demanding trails.
• 3D hollow bonded construction: The hollow crank arm structure reduces weight while increasing rigidity — every watt goes into forward motion.
• Boost-optimised chainline: 55mm chainline is engineered for 141mm and 148mm Boost rear hub spacing, ensuring precise chain alignment across the full 12-speed cassette range.
• Direct Mount chainring interface: Tool-free chainring swaps with Shimano's Direct Mount system — switch ring sizes without removing the crank from the bike.
• Single-ring optimised: Designed specifically for 1x12 drivetrains with superior chain retention geometry built into the chainring interface.
• 165mm crank arm length: A shorter 165mm option that suits riders with shorter inseams or those seeking increased ground clearance on technical terrain.

Construction & Technology

Shimano's HOLLOWTECH II spindle interface integrates the right-side crank arm with a hollow steel spindle for maximum rigidity at the most critical point of the drivetrain. The hollow forged aluminium crank arms are formed under high pressure to create a structure that is both lighter and stiffer than traditional solid forgings. The result is a crankset that punches well above its weight class in both performance and durability.

Compatibility & Fit

The FC-M8120-1 is compatible with Shimano's 12-speed MTB drivetrain (Deore XT M8100 series). Chainline is 55mm, optimised for Boost 141/148mm rear hub spacing. Chainrings are not included — this crankset accepts Shimano Direct Mount 12-speed MTB chainrings. Bottom bracket is not included; a Shimano HOLLOWTECH II compatible MTB bottom bracket is required (sold separately). The TL-FC41 installation tool is required for assembly and is not included. Q-factor is 178mm. Pedal thread is standard 9/16".