Rock Shox RS1 ACS, Solo Air, (inc. service kit)25 years after the original RS-1, the fork that revolutionized mountain biking, Rock Shox does it again. A chassis design never seen before, which integrates the fork's steerer tube, crown & legs into a single carbonmainframe. The all-new Accelerator Damper, which combines incredible small bump performance with an ultra-efficient lockout. & Predictive Steering, a reimagined interface between hub & dropouts which enabled us to create an inverted fork light enough for XC racing & stiff enough for trail riding.