SUM Ultegra Di2Decisions, decisions made easy. With a bike that gives you flat out advantage on the climbs, the sprints and the straightaways, the only decision youll need to make is how nice you want to be to the other guys. A rider oriented design approach ensures a frame that is both rooted and responsive, with a ride experience most aero frames cant match. With a layup engineered to maximize aerodynamics while keeping weight low, the design process for the Sum