Motorized bicycles, commonly referred to as e-bikes, are relatively new in the US and Europe although they have been popular in China for many years where sales actually out-strip motor cars. They are an ideal option for cyclists wanting a little help on hill climbs and for commuters looking for a sweat-free economical mode of transport.
Before rushing out to buy a bike that in theory does all the hard work for you, it is important to understand that an electric bike is designed to offer assisted pedaling as opposed to totally motorized cycling. Whilst the motor can do much of the hard work, especially on hills, the rider is still required to pedal.
In order to keep electric bikes within the bicycle category, speed is limited to between 15–20 mph, dependent on a country’s motor vehicle classification laws. Riders may want to go faster than this which is where pedaling without using the motor comes in. Bicycle weight then becomes very important.
Electric Bicycle Weight
The heaviest parts on an electric bike are the motor, frame and battery. Cheaper e-bikes tend to have heavier motors and batteries which are fine for petite Chinese commuters weighing around 50 kg but not so great for the average 70–90 kg Western adult. The heavier the electric bike, the harder it is to pedal unassisted. This results in increased use of the motor with the possibility of overheating if used for too long and reduced range as the battery runs down more quickly.
Whilst manufacturers are constantly working on ways to reduce frame weight, the average electric bike still weighs around 30 kg, more than twice the weight of an ordinary bicycle. Those looking for a lighter option therefore need to look closely at the type of motor and battery used.
Electric Bike Motors
Motor power determines how fast the bike will go. Speed varies according to rider weight and wheel size as the same motor attached to a 20” wheel has to turn faster when attached to a 24” wheel to reach the same speed.
Most electric bikes use hub motors which are self contained, largely maintenance free and are directly attached to the wheel hub which adds considerable weight to the rear wheel. As they are mass produced, however, they are cheap.
More expensive electric bikes use brush motors, offering higher speeds and better torque which translates into more power. Brushless motors are a cheaper hybrid offering reduced maintenance as they are less likely to overheat.
Electric Cycle Batteries
The battery supplies power to the electronic motor. A fully charged average battery’s range is normally between 12 to 30 miles with gentle pedaling, the actual distance varying according to weight and size of rider and the terrain being ridden. Smooth, dry pavement, for example, will give a much higher range than wet grass or loose dirt.
A rider must be prepared to pedal when moving off or on hills otherwise battery power is severely drained.
Battery types vary from the common, heavy lead acid types used in cars to lightweight and expensive Lithium Ion batteries.
An important factor when looking at electric bike batteries is their recharging time. Cheaper lead acid batteries can take 8 hours to fully recharge whilst more modern Lithium batteries take just a few hours.
Cost of Electric Bikes
Prices range from as little as $200 for cheap Chinese designs with heavy lead acid batteries up to $3,500 for lightweight designs using the latest battery technology. A reasonable quality e-bike will cost around $1,500 so it’s important to look at all the variables before making a decision. Whilst some mainstream bicycle brands like Schwinn and Giant produce e-bikes, most models are produced by niche brands, specializing in motorized scooters and mopeds.
Buying an Electric Bike
With so many variables in motor power, battery type, rider weight and actual bike design, the only real way to tell if an e-bike is right for an individual rider is to take it for a test ride, preferably on the terrain most likely to be used.
Compare motor power, battery life, recharging times and overall bike weight and, above all, be prepared to put a little effort in on hills and start-up before deciding to join the next revolution in eco-friendly transport.
Related Articles
Before buying an electric bike, you may be interested in the Pros and Cons of Riding an Electric Bicycle or converting an existing bicycle with an Electric Bike Kit plus for an alternative green method of commuting, see our article on How to Choose a Folding Bike.
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