The Mavic Crossmax SL R 29in Boost Wheelset is one of our go-to wheels for aggressive cross-country riding and racing. The lightweight carbon fiber layup is exceptionally durable and delivers fast acceleration and precise handling. The Instant Drive 360 freewheel uses a double ratchet system for fast engagement on the trails. The 25mm inner diameter offers the best balance of efficiency and traction, while the tubeless-ready setup and the ability to run up to 2. 4-inch-wide tires give us the grip and traction we need to compete at a high level.