- Shimano 12 speed specific, 55mm chainline for 157mm rear spacing - Provides the optimal chainline and clearance for your Super Boost 157mm hubs when used with the standard Race Face 136mm spindle - Also offers an extra 3mm of chainline when used with Boost 148mm hubs - 7075-T6 aluminum direct mount ring to fit Race Face Cinch system splined cranks - Narrow-wide teeth prevent chain drop, updated tooth profile runs quieter - Installs with a common Park Tool BBT-22
