Regen is available on SuperHero version only. The motor is capable of converting the motion into current feeding the battery, creating a braking force. In order to achive that the chain needs to transmit power to the motor pinion. That is usually prevented by the freewheel on the rear wheel hub. Also, when regenerating the chain will be tensioned on the lower part rather than the upper one as it usually happens. That means that in order to achieve Regen you'll have to switch to an internally geared hub with the freewheel locked. You'll take advantage of the freewheel inside the crankarm so that your pedals won't be dragged by the rear wheel. This will allow you to regenerate when pressing the brakes. Although the motor is capable of generate 10A of current ( 480W at 48V), the amount of energy you can regen depends on the battery you choose: all the batteries have a charging current limit. That's 2A for the 250Wh battery, 5A for the 550Wh and 670Wh batteries and 7A for the 840Wh battery. In order to calculate how much energy you can regen, consider that 10 minutes of regen ( which can be achieved by going downhill) at 5A will give you 40Wh. That's a 7% recharge on a 550Wh battery.