An introduction to electric bikes

  Electric bikes: The ultimate guide

Guide contents

• What are electric bikes?
• Why use one and are there any drawbacks?
• Isn't it cheating?
• How does an electric bike work?
• How far will they go?
• What battery should I get?
• Where is the motor on an electric bike?
• How much do they weigh?
• Do electric bikes need a lot of maintenance?

Electric bike technology has come on leaps and bounds in recent years and household names such as Raleigh, Bosch and Shimano are just a few of the companies jostling to get their products noticed as sales continue to grow along with public awareness of the joys of powered pedalling.

Of course, as with any relatively new or unfamiliar product, there are a host of questions you might have.

What are electric bikes?

An electric bike is really just a bicycle with the addition of an electric motor system designed to help you pedal. Like regular, non-electric bikes, no paperwork or helmet is legally required if they comply with the law, although we would always recommend using a helmet. The electric assist limit is 15.5mph and the motor rating limit is 250W. You must be pedalling for the motor to work. The extra energy is provided by a battery that needs recharging. Power is activated by pedalling or by a handlebar control. Electric bikes are available in just about any style that regular bikes are, from leisure hybrids to mountain bikes and there are even a few road racing bikes with electric assist out there. With an explosion of electric bike sales in continental Europe, the good news is that there is now more choice of models to suit all kinds of riders than ever before.

Why use one and are there any drawbacks?

Electric bike pros

There are many compelling reasons; electric bikes are generally faster than non-powered ones (especially for a rider of average fitness over hilly country), you usually save money if you replace car journeys (or even a second car) or public transport with an electric bike, there are strong arguments to say the extra electric bike acceleration is safer and safer-feeling in traffic than non-powered bikes and they still allow you exercise and save the planet at the same time (they are generally considered a 'green' mode of transport).

Electric bike cons

Drawbacks? Prices have headed up in recent years but this is partly a reflection of better and more reliable technology. They do weigh more than the lighter designs of non-powered bikes. Batteries wear out and are usually several hundred pounds to replace, though better makes of battery should last for several years (see below for more detail).

Isn't it cheating?

I'm never quite sure how to take this comment, often addressed to me when out riding an electric bike! If it means 'you aren't getting the exercise you should', then electric bikes provide plenty of exercise, if that is what you want; you can adjust down the power controls and of course you still need to pedal. You can simply go further for the same amount of effort. If you want even more exercise than on a non-powered bike you can simply turn the motor off. 

How does an electric bike work?

An electric bike can assist you when you’re pedalling. You choose when to have powered assistance and you also choose how much powered assistance you desire. It also means that, if you stop pedalling, you free-wheel just like on a normal bike.

Most electric bkes that are sold should have a speed sensor and most have a torque sensor and crank sensor as well. These sensors feed information to the control unit, which also considers the power level requested and adjusts the power accordingly.  

The amount of assistance is normally measured as a percentage of your own ‘power output’. Depending on the motor system, up to 300% power can be available. If you’re producing 10W of power, the motor will add 30W, giving a total output of 40W. In reality, this makes cycling quite exciting again. 

Whilst it may sound a bit complicated, the reality is that riding a modern electric bike is very intuitive and most people are surprised just how easy and natural it is.

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How far will they go on a charge?

This is much more difficult to know than you might imagine. Battery range depends on power settings (which can usually be changed by the rider via a handlebar control), rider weight, terrain, weather and the efficiency of the bike. Claimed figures are usually under ideal 'laboratory' conditions and you can expect less, often much less. However, even smaller batteries on inefficient bikes should yield around 15 miles, whilst we tested a very large battery on an efficient bike in the lowest power setting and managed around 100 miles over quite hilly terrain. The answer really is 'it depends.'  

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What size battery should I get?

You should ask for the Wh (Watt hour) rating of the battery for any bike you are interested in. 360Wh is standard for many bikes today and may give a range of 20-30 miles on average. However, capacities can now exceed 600Wh. It all depends on how far you envisage going and if you are willing to accept the extra weight and greater replacement cost of a bigger battery. The quality of a battery – roughly indicated by the length of guarantee available – is equally important.

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Where is the motor located?

Usually it is one of two main places, either around the pedals (called crank drives, providing the electric assistance to the chain) or in one of the wheels, powering the wheel, called hub motors. Traditionally, crank drives are preferred for very steep hills and for electric mountain bikes, whilst hub motors, often with throttles, have been advised for weaker pedallers and for town riders who like quick acceleration for nipping in and out of traffic.

But the difference between the two systems seems to be diminishing, with hub motors producing ever more powerful machines that are certainly better hill climbers than they once were. Some makes of hub motor let you put power back into the battery, sometimes called regenerative braking as it also slows you down on descents, though you may still need to use normal bike brakes as well.

This doesn't add a great deal of energy back into the battery but is nice to save wear and tear on your brakes. Throttles are less likely to be featured on new electric bikes from 2016.

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How much do they weigh?

20kg, including battery, is a good benchmark for a lightweight electric bike. Less than this and an electric bike can justifiably claim a tag as a true lightweight. If under 25kg it is still quite good going, especially if equipped with 'extras' such as lights, mudguards and pannier rack or a large battery for extra range. That's not to say 25kg-plus machines should be discounted if they feature lots of extra equipment and a big battery.

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Do electric bikes need a lot of maintenance?

The better designs of today's electric bikes need little more maintenance than a normal bike. The electric components are sealed from the weather and do no need any user maintenance or servicing. You are just advised to top up the battery from a plug socket after every ride (the vast majority of electric bikes have removable batteries). It's a good idea to monitor the capacity of your battery over time using a plug meter that measures Watt hours put back into the battery. Some battery makes allow warranty claims if the capacity falls below a certain threshold within a certain time frame (often two years).

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Browse electric bike companies

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Finished reading?

If you have finished reading our Electric bike FAQs, return to our 'Electric bike ultimate guide'.

  Electric bikes: The ultimate guide

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