From Unconventional CVT Concept to Usable eBike

The challenge

Pedalling torque variability was disrupting cadence control and rider feel in ways that differed depending on whether the rider was on flat ground, climbing, or out of the saddle. The gap between a working prototype and an acceptable product was predominantly in the control behaviour. To resolve the problem PTL worked through a bespoke engineering program, including modelling, calibration and physical testing. 

PTL’s role

PTL began with dynamic modelling to assess target feasibility and quantify system loads. Candidate control algorithms were then evaluated before moving into build and testing. Calibration work was conducted both in a controlled test cell environment and on-road, with data logging to capture real behaviour across conditions. A subsequent system upgrade covered mechanical modifications, a new controller, inverter, battery, firmware, display and datalogger. The combination of these incremental hardware and software improvements, across the whole system, resulted in a significant improvement in system performance and behaviour.

Why it mattered

CVT-based eBike systems are challenging, as control issues are inseparable from the mechanics and rider-feel. PTL’s contribution was to treat the bike as a coupled system through modelling, calibration and hardware development. This approach reduced risk and helped move the programme from a functional prototype to a marketable mobility product.