The e*thirteen Helix Race 107 BCD Chainring, designed for 4-bolt 107 BCD 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, they're 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 cranksM4 narrow-wide tooth profile provides Shimano and SRAM 11/12-speed chain compatibility (Including flattop chains), excellent chain retention, and reduced wear4.8mm 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 aestheticsDurable 7075-T7 construction for long wear-life, stiffness, and strengthItem SpecificationsChainring BCD107ColorBlackDefined ColorBlackDrivetrain Speeds11Drivetrain Speeds12MaterialAluminumRing Position/TypeChain Retaining Single RingRound or OvalRoundTooth Count40Weight74 e*thirteen Helix Race 107 BCD Chainring Chainring EAN: 4711280340989