The game has changed. The Procaliber is back to rule the XC circuit once again. Its IsoSpeed decoupler ensures a stunning cross country performance, speed and feel. The Procaliber 9.9 SL is truly the smartest hardtail on the trail. Key features Race Shop Limited: Pro-level bikes for the most discerning riders Smooth IsoSpeed decoupler: ride faster, stronger, longer Boost148/110: stronger wheels, more tire clearance, shorter stays SL frame saves 250 grams and has Control Freak internal routing Features Smart Wheel Size The right wheel size paired with your frame size gives you the perfect combination of responsiveness and control. Boost148/110 Wider dropouts (110mm front, 148mm rear) give you the stiffness of a 27.5 wheel with all the benefits of a 29 wheel, and Boost148 in the rear lets you run wider tires and a larger chainring without affecting q-factor and pedaling efficiency. Control Freak Cable Management The lightest, quietest, most versatile cable management system allows any combination of shift, brake, lockout, and dropper post lines to be routed through the frame for clean looks and the ultimate custom setup. IsoSpeed decoupler Trek's innovative decoupler allows the seat tube to rotate independently from the top-tube-to-seatstay junction, increasing vertical compliance without compromising pedaling efficiency. OCLV Mountain Carbon Trek's mountain-specific carbon fiber is tougher carbon, with unique materials and layup procedures, Trek's advanced engineering, and a higher standard of testing. Carbon Armor Sometimes you need a little extra protection, so Trek have developed their light, tough external Carbon Armor polymer shield. It provides reassurance when you know your down tube is bound to take some abuse.