Trek Fuel EXe 9.8The Fuel EXe 9. 8 XT takes an evolved approach to e mountain bikes with a revolutionary motor that packs space age technology into a tiny but mighty package. It's built on an OCLV Mountain Carbon chassis that's light, stiff and nimble for a lively and playful trail feel. And to keep a good thing going, it's topped off with carbon wheels, Shimano's clean shifting and ultra reliable XT drivetrain, and the silky smooth performance of a RockShox Lyrik