The RockShox SID SL Ultimate BRAIN incorporates a race-tuned Brain Inertia Valve with Position-Sensitive technology into the all-new RockShox SID SL chassis. New Position-Sensitive Brain technology provides more platform support while maintaining small bump compliance and chassis balance, making this the most efficient BRAIN yet. Position-Sensitive technology allows riders to sag into the fork 15mm for a balanced ride, providing supple small bump compliance and a firm pedaling platform without the need for a remote lockout or levers to flip. All new SID SL Ultimate Chassis features a machined alloy crown to shed even more weight while increasing stiffness.