A Little Extra Help
E-bikes (with a brief look at the power-assist controversy)
Power-assist for bikes is a hot topic, igniting flame wars on cycling websites.
The controversy is fueled by a big question that has no easy answer: does power assist "pull" from the cyclist and pedestrian world -- seducing pure cyclists to add more and more power to their bikes and drawing pedestrians away from mass transit and walking? Or does it enable drivers to abandon cars and SUV's for a healthier, more-sustainable lifestyle?
Worldwide, will affordable, readily-available power-assist for bicycles increase consumption of resources and generation of pollutants? Or will it lure drivers from cars to less-polluting, less-expensive, less space-consuming e-bikes?
Locally, will power-assisted bikes complicate traffic patterns and push "real" cyclists aside on streets and cycleways? Or will they reduce car traffic, generate demand for better bike parking and other cycling facilities, and help clear the local air?
Personally, will power-assist make me lazy, fat, and rude? Or will it motivate and enable me to bike places I would have driven, and keep me cycling when my aging joints would otherwise have given out?
The photo below illustrates the good side of power-assist -- somebody who could afford to drive a car figures out how to bike instead. He uses power assist to get past the barriers that would keep him from switching to a regular bicycle. For most of the power-assist enthusiasts on the Internet, the choice of an electric assist bike is a move toward less pollution and a healthier lifestyle.
For the world's far more numerous poor, an e-bike is a step away from human power, but a step with undeniable advantages for the individuals concerned.
To keep ourselves and our environment healthy, we need to move drivers in developed countries from cars to bikes while encouraging the developing world to keep human-power viable and avoid over-dependence on internal combustion engines. Power-assisted bicycles have a definite role in both areas.
Leaving the pessimistic view to others, let's look power-assist options, and what they can do:
This bike was converted to power-assist by adding a hub motor to the front wheel. The batteries are in the three white tubes below the seat. Several Minnesota HPV Association members (including Mark Stonich, seen in the background) tried it and talked with its owner at a MnHPVA ride. With electric assist, the owner could handle a commute that was too long for him to manage on a regular bike. Combining front-wheel electric drive with rear-wheel pedal-drive, he also had better traction on slippery surfaces.
What's available?
Mostly, we are talking about electric systems, though small gasoline motors can also be used on bicycles. If the motor is built into the hub of the wheel, it is a hub motor. The power can also be delivered directly to a tire (friction drive or roller drive - used on the French SoleX bikes that were popular after World War II), through the spokes, along the chain, at a secondary axle, or at the bottom bracket. One way to add temporary power assist is through a powered trailer (also here and here). Read more about power assist options and systems here, here and here. For an account of designing and installing an assist system, click here. For discussions of power-assisted bicycle sidecars, click here.
The power can be controlled by a throttle or through a system that detects and augments the cyclist's own efforts and cuts out when he or she stops pedaling (pedelec). The power-assist can be proportional to the rider's pedaling force or can be varied.
For nearly-invisible electric assist (concealed in the frame) that will give you an extra boost over a hill or into a headwind, Schwinn is promoting a line of electric assist bikes, new in 2007. Batavus in the Netherlands has been offering the similar "onzichtbare motor" (invisible motor) for some time now.
Bionx sells a power-assist system that allows the rider to generate and store excess power on downhills and use it to maintain speed going up. Frederik Van De Walle has used the Bionx system on a WAW velomobile and reported on it in a blog.
A to B, a small magazine from England, now available through on-line subscriptions, reviews electric bikes and folding bikes -- and electric folding bikes. They publish a wealth of on-line advice, including "Why choose an electric bike?"
Electric-Bikes.com includes comparative information on electric bikes, and a lot of material on other electric vehicles.
Kinetics is an electric bike supplier in Scotland, with a webpage that provides information on the Heinzmann system and other electric bikes.
A useful Yahoo discussion group with extensive archives is the Power-Assist mailing list.
