Hub-centered power assisted bicycles
Hub-centered power assisted bicycles use a sealed lead-acid rechargeable battery in a similar way to a hybrid engine, storing energy while riding, or recharging from a wall socket.
In Motion Technologies in Dandenong have developed an axial flux motor to produce the Avanti Electra bike. The motor has no moving parts and is smaller, lighter and more efficient than other power-assist motors. It delivers up to 200 Watts of power to the front wheel to assist the rider either in hill climbs or in extending riding distance beyond that which the rider would be capable of alone. Newer versions (eg by Sanyo) will also recover and store energy used in braking.
In cases where the battery is recharged by the user, a high level of sustainability authenticity is expected. When charged by an external source, the electricity source must be considered when evaluating whether it is a greener option than an unassisted bike. The potential of the technology to enhance city life by reducing car use is also a benefit, but a full LCA would be able to provide the most robust assessment.
NOTE: There are a number of versions of power assisted bikes. They range from simple hybrid type bikes to the full petrol motorised mopeds. Their sustainability authenticity is extremely variable, and each must be assessed individually using robust analysis. In some cases local legislation will limit and define what is and what is not a bicycle.
From “Innovation in mobility for sustainable outcomes” case studies by Geoff Browne.