Brian Wismann, Brammo Director of Product Development, about regenerative (regen) braking- from BrammoFan’s site:
1. Not enough energy to be regenerated off the rear wheel of a lightweight motorcycle. Most braking force is applied to the front wheel of a motorcycle (some 70%) – and applying braking force to the rear wheel is a tricky deal without knowing traction conditions. All of this at the maximum benefit of much less than 10% increase in range.
2. Regen turns your motor into a generator – which means it’s working when it might otherwise be resting. This adds heat to the motor and can reduce the service life of the motor by increasing the duty cycle.
3. Control – regen is a variable parameter and probably requires an additional hand control to be done properly. Vectrix did this by twisting the throttle forward, which was elegant but also presented problems. New riders were slowing only with regen and failed to learn how to apply the true mechanical brakes properly when they needed to stop fast!
4. Range – in most cases, you’ll experience greater range by “free wheeling” and coasting with no regen than you would if regen kicked in when you let off the throttle.