In mountain biking's heyday, Procaliber was the envy of all other race bikes. Now it's back to rule the XC circuit once again, redefining the term “hardtail” and setting the bar for speed and smarts. The 2017 Trek Procaliber 9.9 SL Race Shop Limited IsoSpeed decoupler delivers uncompromising cross country performance, efficiency, and an incredible ride feel. It's the fastest, smoothest, 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.