Variables affecting range achieved on an electric bike need to be considered if you are thinking of purchasing your first electric bike, or replacing an older one, you will want to have an idea of how far you are going to go with the pedal assist. Below, I look at several variables which will have a bearing on the answer. But if want a quick rule of thumb, then you can use the following easy formula and make some extra variations for your own circumstances.
If you are planning to use an electric bike because a push bike has become unenjoyable, you are an average weight and want some exercise, you will ride in a slightly hilly area, use the gears sensibly on reasonable roads without heavy stop start traffic, then you can use the following formula.
Quick Formula
You can short cut analysing the Variables affecting range achieved on an electric bike by using this quick formula
With a 36V bike find out the Ah of the battery. This may be printed on the battery or it may say how many Wh. the battery delivers. Let’s say it is 36V X400 Wh.
Divide the Wh. by 36. 400/36 = 10.4Ah. Multiply the answer by 3. 10.4 X 3 = 31.2 miles
Generally, an average rider will get 3 miles rage for every battery Ah.
Variables
But let’s look at some of the many variables in more detail:-
The Rider
What is your weight? A rider weighing 120Kg + 25 Kg for the bike might get 30 miles, whereas an 70Kg person + 25 Kg with the same set-up might well achieve 37miles
Pedalling Speed
How fast do you pedal? How much effort do you put into the bike for a certain speed? 120Kg rider pedalling at 35rpm at 12mph will reduce the range to 27 miles, but if he pedals at 90rpm the range increases to 31miles. Similarly, the 70kg rider increases from 34 – 39 miles range. We will leave them both at 60rpm for the rest of the test.
Average Speed
We have been assuming that our 2 riders have been averaging 12 mph. If the 125Kg rider speeds up to 14 mph, range reduces from 30 – 27 miles and by slowing to 10mph it increases to 33. Similarly, the 70Kg rider decreases from 37 – 33miles at 14 mph and increases to 42 at 10mph.
Power Selection
So far, we have assumed the rider only uses the “Tour” riding mode. Increasing the power to “Sport” or “Turbo” can reduce the range. 120Kg from 30 to 26 and the 22 mile range at 12mph. Similarly, the 70Kg rider goes from 37 – 32 then 28 miles
The Bike
The bike needs to be in good physical condition and well lubricated. We have assumed that the rider has been riding a city e-bike with hybrid bike tyres. Changing to MTB tyres could reduce the range by up to 10% due to the extra rolling resistance. Different bike styles will also affect the mileage achieved.
The Battery
The capacity of the battery will affect the mileage achieved. Batteries are expensive. If you are considering a 300Wh battery, using the quick formula above, we calculate 8.3Ah X 3 = 25 miles. But then, if the rider is 120Kg, pedals 35rpm at 14mph on turbo power with MTB tyres, the range could be reduced to as little as 15 miles. On the other hand, the 120Kg rider with a 500wh battery rides at 90rpm at 12mph on Tour with Hybrid tyres is estimated at 40 miles.
Strong Winds
Can reduce your range
Hilly Terrain
Will reduce your range. To minimise this effect, you need to use the gears on the bike to maintain the amount of effort you put into the ride. If you just turn the power up to turbo, range will fall.
Road Quality
Riding on a poor quality surface such as unmade tracks or across fields will reduce range
Stop/Start Riding
If your route has a lot of stop/start – such as traffic lights – range will be reduced. Frequent acceleration from a stopped situation will use extra power and reduce overall range
Summer or Winter
E-bike lithium batteries do not perform as well at colder temperatures. Performance usually drops off up to about 10% when the ambient temperatures fall below 10 degrees C. You might find it beneficial to take a warm battery from your home and install it on the bike just as you are about to set off.
Motors
All motor types are different. If you choose a high torque motor because it delivers more power, the range is likely to be less than a low torque motor
Conclusion
You can now understand that there is a multiplicity of factors that reduce or increase the range that you will achieve on your electric bike. We want all customers to be pleased with the performance of their e-bikes and for the bike to be suitable for their expectations. If there are a range of batteries offered with the bike you choose, selecting a battery does not deliver the range you need is an expensive error if you then have to purchase a battery with greater capacity.
We hope that this article will help you make the correct decision.
Acknowledgement
The estimates quoted in this article have been calculated using the Bosch e-Bike Range Assistant with the setting on Winter.
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