Electric Bicycle with Hydro-formed Frame

This thesis project by Vojtech Sojka for Superior Bikes looks to change the game without straying too far from the norm. It has a hydro-formed aluminum frame with the motor positioned in the bottom bracket, for a clean look and better weight distribution than a motor in the rear hub. The battery is also centrally located in the seat tube, and a carbon belt drive with a Shimano Alfine hub completes the drivetrain.

The designer explains:

“After trying the to design the frame with standard diamond look with a complicated dropout system, I decided to eliminate the seat stays which enables the user to put on the belt easily. This solution requires a small weight increase (about 200grams), but manipulating the belt is much easier. Also, it enables a little bit bigger deflection of the rear ‘triangle’, which improves rider comfort.” Speaking of comfort, the wide Schwalbe Super Moto 2.35” tires also cushion the ride. Even though they complicated the design of the short chainstays, Sojka felt like the extra tire clearance was a worthwhile feature work through in his design. His solution features rear facing dropouts and a pivoting brake caliper flange. “Compared to the other solutions, its much easier to set the right position of the rear wheel and the brake – the whole caliper simply moves with the rear wheel, so the brake will be always in the right position.”

Hopefully, Superior will move forward with the concept, and we will see continued development of Sojka’s design in the near future.

Designer: Vojtech Sojka for Superior Bikes