The Shimano FC-RS520 brings 105-tier 12-speed performance to road cyclists who want reliable, capable gearing without compromise. Designed for 2x12-speed disc brake road bikes, this crankset delivers the precise shifting and robust construction that Shimano's drivetrain engineering is known for — making it an ideal upgrade or build component for enthusiast road riders.

Highlights

• Hollowtech II spindle interface: integrated crank arm and spindle system for a stiff, lightweight power transfer and simplified installation.
• 110mm asymmetric BCD: 4-arm asymmetric chainring bolt circle accommodates both 50T outer and 34T inner chainrings for a compact double setup suited to a wide range of terrain.
• 12-speed drivetrain compatibility: works with Shimano 12-speed HG road chains and 105 R7100 / compatible groupset components for smooth, precise shifting.
• Disc brake road frame geometry: engineered Q-factor of 150mm and 44.5mm chainline optimised for modern disc brake road frame standards.
• Wide crank arm length range: available in 165mm, 170mm, 172.5mm, and 175mm to suit different rider proportions and fit requirements.

Design & Construction

The FC-RS520 uses a two-piece, 4-arm crank construction with Hollowtech II interface — Shimano's proven outboard bearing system that positions the bearings wide of the shell for increased lateral stiffness. The asymmetric 4-arm spider keeps chainring bolts evenly loaded across both rings, contributing to consistent chain retention under load.

Compatibility & Fit

Designed for 2x12-speed road drivetrains. Chainrings: 50/34T. BCD: 110mm asymmetric. Spindle interface: Shimano Hollowtech II (24mm). Q-factor: 150mm. Chainline: 44.5mm. Compatible with 68mm and 70mm threaded BB shells (bottom bracket sold separately). Frame compatibility: O.L.D. 135mm with minimum 410mm chainstay length. Compatible with Shimano 12-speed HG road chains.