Thinking of buying an electric bike? If you’ve started to do some research on the best electric bicycle motors, you may well have got confused. How much power do you need for power assisted bicycling? Why is maximum power output so much higher than the legal limit?
The answers are not straightforward as you also have to look at battery size and how you plan to ride the bike, but this article aims to clarify the main points to consider.
Electric Powered Bicycles
The first questions you need to ask yourself are where you plan to ride and whether you’re happy to do some of the pedaling as the power, measured in watts per hour required, will be affected by how hard the motor has to work to propel the rider on steep hills.
Motor power, drawn from the electric bike battery, is measured in volts and you will see electric bicycle motors advertised with 12, 24 or 36 volts. The amount of power produced, however, is dependent on the flow of amps or current from the motor as you need to multiply the voltage by the current to get power output expressed in watts; a motor drawing 20 amps x 36 volts from the battery pack, for example, will produce 720 watts of maximum power.
Electric Motors for Bicycles
Electric bicycle laws vary by country and in the US by state, but in the UK, the legal limit for e-bikes is 200 watts of continuous power. Maximum power output, however, as in the example above, is usually much higher because most people want the bike to do most of the hard work on hills. If you only have a motor and battery combination capable of producing say 240 watts (20 amps x 12 volts), then you will either have to do a lot of the pedaling with only gentle assistance, or accept a very slow ride to work.
As a comparison, for instance, the average cyclist can produce around 100 watts of power continuously, increasing to several hundred watts only for short bursts before exhaustion kicks in. Power produced by electric motors for bicycles should be viewed in a similar way.
Maximum Electric Bike Motor Power
The maximum power generated by any electric bike motor and battery combination can only be sustained for a brief period without some level of pedaling; otherwise the motor will burn out. So riders who want to use an e-bike for riding steep inclines will want the highest possible maximum power output to minimize the amount of additional pedaling required. Someone looking for gentle assistance on flat terrain, on the other hand, may only need a maximum power output that is just above the legal continuous power limit.
When comparing e-bike specifications, remember also that actual electric bicycle motor performance depends on the motor’s efficiency, type of electric bike battery, road conditions, and the rider’s weight and fitness level.
Which Electric Bicycle Motor is Best?
To decide which electric bicycle motor is best, you need to determine whether you want the motor to do all the hard work or whether you’re happy to pedal a lot to extend the mileage before the battery needs to be recharged.
Buy an e-bike/battery combination with a high maximum power output around 900 watts if you plan to ride steep hills with minimal effort or look for an e-bike with a lower number of watts if you just want a gentle assistance.
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Also of interest may be
- Electric Mountain Bikes: Where to Buy, Cost and Best Brands
- Cheap Folding Electric Bikes with LiFePO4 Bicycle Batteries
- Electric Folding Bicycles for Easy Healthy Bicycle Commuting.
Helen Smeaton - Helen Smeaton runs a cycling and hiking business and is also a freelance writer and web designer. Read her profile for more information
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