1) First ride a Panasonic unit powered bike to set a marker standard to judge from.
2) Hill climbing.
3) Smoothness of transition at the 15 mph cut-off speed. Some have an unpleasantly abrupt transition.
3) Action of any torque sensor, some designs have harsh responses to changes in pedal pressure.
4) If a throttle/pedelec dual mode design, switch to pedelec and see if it has progressive power. Some just blast straight into full power as soon as pedal rotation is detected, disconcerting and dangerous when confined in heavy traffic.
5) Check to see if the control method suits you, many different types on the market, e.g. throttle action with pedelec, torque sensor only, pedelec only when throttle not switched to etc.
6) What is it like to cycle with power switched off?
7) Try a fast downhill if possible to see how stable it feels. This is a good test for frame/forks stability and overall bicycle design.
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