What are Electric Bikes?
Most of 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. Some of the bikes (for example the Wisper bikes in our range) do have a throttle as well. This can be used only in combination with the pedals but means that you have access to even more power. Provided that the bikes comply with the European Regulation EN 15194 they do not have to be taxed or insured and the rider does not need a license. You can ride an electric bike in the Uk anywhere that you can ride a non-electric bike.
How do they work
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 the sensors that detect pressure being applied to the pedals gives a more immediate response. It also means that the weight of the motor is in the middle of the battery, giving better weight distribution and being lower down ensures a lower centre of gravity. The motors are 250 watts continuous output and are brushless.
The Bosch Performance Line CX motor used in the higher performance electric bikes
The batteries are lithium ion and are typically held on the down tube or on a rack on top of the rear wheel. The capacity of the battery is measured in amp hours or watt hours. The Bosch battery comes in three sizes – 300, 400 or 500 watt hours. A 400 watt hour battery will give the bike a range of between 40 and 80 miles depending on the level of assistance used – i.e. 40 miles would be in the highest level of assistance (or ‘Turbo’) while 80 miles would be in Eco. Most people will find the range they achieve varies according to how much assistance they use, typically falling somewhere in the middle as they adjust the assistance according to what they need. The 500 watt battery will, logically, give you 25% more range. For most people a 400 watt hour battery is more than sufficient but 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.
The Bosch Powerpack 500 for the rear rack (left) and downtube (right)
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 Bosch motor senses the effort that you apply to the pedals through a torque sensor and re-calculates this 1,000 times per second.
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:
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:
- The motor must not have an output of more that 250 watts continuous.
- 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.
- 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 usd up to 15.5 mph.
- In the UK you need to be at last 14 years old to ride an electric bike.