The 2017 Pivot Mach 4 Carbon offers the perfect balance of speed and nimble handling. Like its bigger-wheeled sibling, the 429SL, the 2017 Pivot Mach 4 Carbon is a demon on any cross-country racecourse—proven in both the Olympics and on the World Cup circuit. But with a bit more suspension travel, mid-size 27.5 wheels and a shorter wheelbase, the Mach 4 Carbon possesses a playfulness that makes it a blisteringly fast trail bike.