Electric-bicycles use lithium ion batteries as their power source. On Pedal Assist e-bicycles, the electric motor is activated when pedalling. Pedal-assist setups supplement the efforts of the cyclist as he/she pedals. These bicycles have sensors mounted on the bottom bracket to detect the pedalling speed and force, and the assist mechanism responds by providing additional momentum. The motorised assistance engages only when the rider is pedalling, hence the name 'Pedal Assist'. Brake activation can be used to disable the motor. The Pedal Assist electric drive system is limited to a speed of 25 kmph on most e-bicycles in the Indian market, and its motor is relatively low-powered.