The Shimano 105 FC-RS520 brings proven 12-speed road performance to a wide range of builds. Featuring Hollowtech II spindle technology and a compact 50/34T chainring combination, it's the ideal upgrade or OEM replacement for disc-brake road riders who want reliable, efficient power transfer without compromise.

Highlights

• Hollowtech II spindle interface: Shimano's industry-standard two-piece crank design delivers stiff, efficient power transfer and straightforward installation.
• 12-speed compatible: Engineered for Shimano's 12-speed road drivetrain, working seamlessly with 105 R7100 and compatible groupsets.
• Compact 50/34T chainrings: A versatile gear range that handles fast roads and challenging climbs with equal confidence.
• 110 asymmetric BCD: Shimano's asymmetric bolt circle design optimises chainring stiffness and shifting precision across both rings.
• Four-arm construction: Lightweight aluminium arms keep weight low while maintaining the rigidity needed for sustained road efforts.

Design & Construction

The FC-RS520 is a two-piece, four-arm crankset built around Shimano's Hollowtech II bottom bracket interface — the same reliable spindle system used across Shimano's road range. The aluminium crank arms are anodised black, and the asymmetric 110mm BCD chainring mounting pattern is shared with the 105 R7100 series, making ring upgrades straightforward.

Compatibility & Fit

Designed for 12-speed road drivetrains. Compatible with Shimano Hollowtech II bottom brackets (BB-RS500 threaded or BB-RS500-PB pressfit — not included). Suits road disc frames with 135mm or 142mm rear axle spacing and a minimum 410mm chainstay length. Chainline: 44.5mm. Q-factor: 150mm. Pedal threading: 9/16". Not compatible with 11-speed or rim-brake-specific drivetrain configurations requiring a different chainline.