Our patented shaft drive technology delivers an extremely smooth and safe ride with low maintenance and no mess. Dynamic uses a more advanced shaft drive using spiral bevel gears in a lighter weight and more compact design. This means it takes less pedaling effort to propel the bike forward and to maintain cruising speeds * Internal Gear Hubs provide fast and seamless gear changes, with shifting independent of pedaling * Dynamic fully tunes every bike before it is shipped to our customers - including truing the wheels, setting the brakes, inflating the tires, testing the gearing, and adding your selected accessories. Dynamic"s frames use an aircraft grade 7005 aluminum for strength, light weight, stiffness and durability * Frame: 7005 AluminumGearing: Shimano Nexus Premium 8-speed internal hub (range of 18-gears)Shifter: Shimano Rapid FireCrankset: Forged alloy crank armsRims: Alex double wall alloyTransmission: Sussex 3rd Generation Shaft Drive System * Tires: Kenda 20" x 1.75"Frame Sizes: 14"