e*thirteen Helix R 107 BCD 4-Bolt Chainring - 40t 11/12-Speed 107BCD Black. The e*thirteen Helix R 107BCD Chainring designed for 4-bolt 107BCD cranks like SRAM Red or Force including power meter equipped cranks offers a performance upgrade for Gravel and Road cyclists. The 38 40 and 42 tooth rings pair perfectly with e*thirteen’s cassettes for more overall range and higher top speeds. Made from durable premium 7075 alloy theyre CNC sculpted for a high stiffness-to-weight ratio. Compatible with both SRAM and Shimano 11 and 12-speed drivetrains. Chainline is set by SRAM® Crank assembly.

Compatible with 4-bolt 107 BCD SRAM® cranks and Quarq® power meter cranks

M4 narrow-wide tooth profile provides Shimano and SRAM 11/12-speed chain compatibility (Including flattop chains) excellent chain retention and reduced wear

4.8mm offset (Chainline is determined by SRAM® Crank assembly 45mm for normal width cranks 47.5mm for wide cranks)

Forged from premium 7075-T7 aluminum then extensively CNC optimized for light weight and technical aesthetics

Durable 7075-T7 construction for long wear-life stiffness and strength