The Apex features an integrated battery and motor system; upgraded adjustable air-suspension fork; optimized suspension with 150 millimeters of travel; Modes- 5 Levels of Eco-Assist, 5 Levels of Sport-Assist, Throttle, Walk Assist Mode; 4-Piston Tektro hydraulic disc brakes and a wide range 9-speed SRAM drivetrain. The Apex uses a 12mm thru-axle on the rear and sealed bearings in both front and rear hubs for maximum performance and capability. The Apex is the pinnacle of QuietKats hardtail electric bike lineup. Bike fit- small under 5'6", medium 5'6" to 6' and large 6' and up.