What are Electric Bikes?

The bikes that we sell are pedal assisted or pedelecs. This means that the motor will not start until you start to pedal and when you stop pedalling the motor will stop. Bikes with a throttle are not outlawed but beyond 4 mph it can only be used in combination with the pedals. In our experience the bikes that have a throttle are not as good as the bikes that do not have a throttle. The amount of assistance that is available from the motor means that in the vast majority of cases a throttle is simply not necessary. On Bosch powered bikes, there is the ability to power the bike at walking speed without pedalling – it’s called Walk Mode.

Provided that the bikes comply with the European Regulation EN 15194 they do not have to be taxed or insured. You can ride an electric bike in the UK anywhere that you can ride a non-electric bike. All of the bikes that we sell comply with this regulation.

How do they work

The Motor

Electric bikes have a motor that can be fitted to the front or rear hub or can sit in the bottom bracket (between the pedals). Each position has an advantage appropriate to different riding styles. When the motor is in the bottom bracket torque sensors ensure that you get an immediate response. It also means that the weight of the motor is in the middle of the bike. This gives better weight distribution and being lower down ensures a lower centre of gravity. The motors are 250 watts continuous output and are brushless.

By and large the motors that sit between the pedals (crank drive or mid-drive motors) are better, often more powerful and more sophisticated. Most importantly they work in a different way. A crank motor responds to the pressure (torque) that you apply to the pedals and then multiply this. A motor on the wheel however does not normally respond to your torque but just go at a set speed according to the level of assistance that you have selected. This makes the crank drive motor feel more natural and gives a greater feeling of control. It is certainly our preferred system. A motor on the wheel works perfectly well however and because you only need the pedals to moving, with a minimal amount of pressure some people prefer it. It does the job very adequately and tends to be cheaper.

The Bosch Performance Line CX motor used in the higher performance electric bikes

The Battery

The batteries are lithium ion and are typically held on the down tube or on a rack on top of the rear wheel. Increasingly the batteries are inside the down tube, so that they are not visible at all. The capacity of the battery is measured in amp hours or watt hours. The Bosch battery comes now in four sizes – 300, 400, 500 and most recently 625 watt hours.


A 400 watt hour battery can give the bike a range of about 70 miles depending on the level of assistance used, the type of bike and where/how it’s being ridden. However the broad rule of thumb we use is that a 400 watt hour battery will give a range of about 40 miles, a 500 watt hour battery 50 miles etc. This assumes average use of the levels of assistance and on varying terrain. It is by no means a best case and is what we believe is very achievable.

Bear in mind however that the range can be affected by a number of factors – the weight of the bike, weight of the rider, the pressure in the tyres and very significantly the terrain; the range on the road will be much more than off road. For a lot of people we find that a 400 watt hour battery is more than sufficient. However if you want to be sure and are planning to use the bike for touring, for example, then you can consider the 500 watt hour battery or even the 625.

What battery do I need?

The battery should last a long time if it is looked after. The Bosch batteries for example have a very good battery management system. This means that when the battery is not used for a while it will go into a sleep mode. This prevents the cells from going into a deeper dormant state from which they cannot recover. The range of the battery will go down over time but the reduction is very gradual. After 5 years we are yet to replace a Bosch battery for a customer because they are no longer getting the range that they need.

It is worth getting the battery size right from the outset. Replacement batteries are expensive (the new 625 Wh battery costs over £750). Remember as well that a larger battery will last longer than a smaller one. It is possible with some bikes to choose the battery size. This applies for example to some of the Moustache bikes and to the Gazelle bikes. However with most brands the battery size is determined by the model, so that the very large batteries are only available on the more expensive bikes.


PP500_w486The Bosch Powerpack 500 for the rear rack (left) and downtube (right)

Walk Mode

Many of the bikes have an independent walk mode. This enables the user to move the bike slowly forward without engaging the pedals – useful for particularly boggy terrains or tough hills where you have dismounted the bike.

The Control Unit

The bikes can be ridden in different modes controlled by the control unit on the handle bars. The mode that you choose determines the amount of the assistance that the motor gives back to you. This varies according to the motor manufacturer but with motors that have pedal sensors the principle is the harder that you pedal the more assistance the motor gives to you. For the Performance Line Bosch CX motors the additional assistance that you get with derailleur gears from the motor is as follows:

Eco Mode:50%

Tour: 140%

EMTB*: 140-340% (*Dynamic mode with bigger torque range)

Turbo: 340%

Other systems work in a different way or have different power capabilities.

The Law and Electric Bikes

The basic elements of the law as applied to electric bikes are:

  1. The motor must not have an output of more that 250 watts continuous.
  2. The assisted speed must be limited to 15.5 mph (25 kph). The only place that you can use an unrestricted bike is on private land with the landowner’s permission. Some may lead you to believe that ‘off road’ is ok. This is not the case.
  3. A throttle can only be used without the pedals being engaged up to 4 mph. If the pedals are engaged (i.e. moving, even if slowly) then a throttle can be used up to 15.5 mph.
  4. In the UK you need to be at last 14 years old to ride an electric bike.