If you already have a bicycle, but want to take advantage of the benefits of an electric drive, such as extending your practical riding range or boosting your top speed, you don't have to buy a whole new all-electric bike.
Instead, you can use an efficient friction-drive module, such as the Rubbee, that can quickly and easily turn your current bike into an electric bike when you need it to, but can also pedal it old-school when you want to.
The Rubbee module connects to the seat post of almost any bicycle and uses rollers made from a special polyurethane blend to transfer the power from its powerful (250W rated, 800W peak power) electric motor to the rear tire.
"The Rubbee Drive uses a revolutionary easy way of attaching an electric drive. After the first initial installation the drive can be attached and detached in just a matter of seconds. This allows the system to be used by everyone - as long as they have a bicycle."
With an integrated 20000 mAh battery (capable of a range of about 15 miles in fully-electric drive mode) providing the energy, and handlebar-mounted throttle controlling the amount of electric assist, this 14 pound module can is said to enable a top speed of about 15 mph on most bikes.
The Rubbee can be used in "freewheel" mode (with no electric assist), in partial assist mode (pedaling manually while being assisted by the device), or in fully-electric mode (no pedaling necessary), so riders can use it as they desire in order to either extend battery life or speed up their commute.
The device is housed in a CNC-machined aircraft-grade aluminum chassis, and is said to be able to be installed or removed in less than a minute, which means that swapping the Rubbee onto another bike you own is a quick and easy process. The Rubbee battery charges in about two hours, and it has an integrated battery management system to ensure that the battery pack "is healthy for thousands of cycles."
Rubbee just finished a successful crowdfunding campaign on Kickstarter, and while I didn't see any way to order the module on their website just yet, with any luck the Rubbee will be available to order online once the company gets up to production level.