Trek’s unique IsoSpeed road bike and cyclocross comfort tech has been translated to full-on mountain bike use with the Procaliber cross-country machine. We’ve previously spent a little time on the top-line 9.9 and mid-range 9.8 models, but recently got in the humbler 9.7 version to give it a thorough interrogation as to whether IsoSpeed is a winner on the trail.
The IsoSpeed coupling replaces the normal fixed joint between top tube and seat tube with a pivot. Add a flattened lower seat tube section, and the top of the seat tube is able to move independently of the rest of the frame if the bike hits a bump.
‘Boost’ rear hub spacing (148x12mm) for extra tracking stiffness, neat cable/hose management and two bottle cages complete a slick and contemporary frame. The smallest size (15.5in) runs on 650b wheels while the other four use 29in wheels to keep size and shape proportional.
The IsoSpeed coupling allows the seat tube to move independently of the rest of the frame
You can read more at BikeRadar.com