A guide to the types of ebikes currently available in the UK
What is an ebike?
An ebike is a bicycle with an electric motor to assist propulsion. The motor is powered by a rechargeable battery, and its operation is governed by a controller.
What types are there?
Basically two, a motor which is bolted to the bottom bracket and drives the cranks, known as a crank drive. The second type uses a hub motor which is laced into either the back or front wheel, known as a hub drive.
What are the advantages and disadvantages of the two systems?
A crank drive rides more like an ordinary bicycle because it drives through the gears, which the rider uses in the same way as a push bike. A hub motor works more independently of the rider, so can feel more like (a very underpowered) moped.
There are two types of hub motor: direct drive
and geared
. The direct drive motors rotate all the time and drain pedal power energy when the system is not active. The better design is the geared hub motor which allow the motor to "freewheel" when not in use, which allows the bicycle to ride like a "normal" bicycle when electric assist is not in use.
The front wheel drive hub motors do exhibit some strange characteristic in wet weather on slippery surfaces e.g. drain covers where the front wheel can lose grip.
How long does the battery last?
Depends on the size of the battery, the riding conditions, and how much assistance you ask for via the controller.
Batteries are measured in amp/hours (Ah) and are usually around 10Ah or 15Ah. 20Ah batteries are available but are generally a lot more expensive. A 10Ah battery in favourable conditions could last 40 miles, but against hills and headwinds that could drop to under 20 miles. (The large capacity batteries are heavier and much more expensive).
What about throttles?
Throttles are legal in the UK but not everywhere in Europe, so most manufacturers don't fit them. Power is governed by fixed settings, usually about five, which the rider chooses via a button on the handlebars. The controller then varies the power delivery depending on how fast you are pedalling, and in the more advanced systems, how much torque you are applying to the pedals.
Throttles are available for some aftermarket kits. While it's tempting to want and use one, holding a throttle open for a long period of time is wearing, and some people find it difficult when they are pedalling as well. The use of a throttle does reduce the range as the throttle is "power hungry".
The majority of kits have a controller and pedelec controller, so the rider has a choice of using set power levels and / or the throttle. The more upmarket kits have a LCD screen with Mph, odometer, battery voltage and power setting.
The pedelec system cuts in after a couple of revolutions and cuts off when you stop pedalling and provides a controlled electric assistance.
What's the legal position of ebikes?
The EAPC regulations state that in the UK for an ebike to be legally a push bike it must have a motor of no more than 250 watts continuous power and the motor must cut out at 15mph (=/-10%). The speed cut out is not negotiable, the watt rating is more complex because all motors deliver more peak power when the controller demands it. There are other regulations regarding braking efficiency etc. and the regulations can be found online.
Nearly all complete ebikes sold in the UK are UK legal. The position is different with aftermarket kits where there are lots of higher power motors on sale. I've not heard of anyone being prosecuted for using a high power kit, but legally they are not bicycles, so cannot be used on cycle paths and should have a number plate, and insurance.
Some ebikes with legal motors can be derestricted - the 15mph speed limit removed. This makes them illegal and often doesn't help a great deal - the motor is tuned for torque, not speed, so provides a lot less assistance the faster it goes.
How much do ebikes cost?
Anything from £500 to £5K+. As with ordinary bicycles, you get what you pay for. The motor and battery are heavy metal and valuable, so make up £500 or more of the cost. On a £650 ebike, the bicycle part will be cheap and nasty. Paying more than £1,000 will get bike components of medium quality.
The low cost ebikes use sealed lead acid (SLA) batteries. These are heavy and despite the rating of the battery the range is limited due to the construction of the battery at their 1 hour rate. Nicads were used in some early ebikes, again old technology and suffer from "memory problems and premature failure". The current Models use mainly Lithium, LifePO4 or LiPo batteries and further variants are now in production.
Some of the low cost ebikes use brushed motor technology. These motors are heavy and do not produce as much power as the later brushless motors.
The controller and motors are not interchangeable between these two systems
What about converting my bike?
A good option if you are reasonably competent mechanically and electrically. Converting enables you to choose the bike and the motor/controller/battery combination - handy if you have specific needs. It can be a bit cheaper, but a quality battery is about £300 and a hub motor £100+. Add a controller and a few bits and pieces and the parts bill will come to around £500. (
Fitting a front hub motor to alloy front forks IS NOT RECOMENDED).
Crank drive kits are more expensive, but simpler to fit because there's no messing around with lacing a wheel, and the wiring is more straightforward.
Most kits come from China and quality is variable, some very good, others poor. BMS supply some good quality kits but beware the lower prices, once import duty, UK VAT and carriage is added to the price it does mount up. In most cases the duty is payable to the courier before delivery.
What's not to like about ebikes?
They are all heavy - 20kg+ - so the cycling experience is not as pure as on a push bike. The weight also means they are hard to pedal unassisted, which can be a problem if the electrics fail or the battery goes flat.
Another disadvantage is the weight makes ebikes unwieldy at A gates and other restrictions. Lifting one on to a train, up stairs or car rack is hard work.
Fixing a puncture is more complex on a hub drive - no quick release and the motor needs to be disconnected. Less of a problem with a crank drive, but there's still the weight to contend with. (
There are some tubes available now that are made to fit without removing the wheel from the bike).
Hub drives torture spokes, so breakages are more common. That can be sorted by a properly built wheel, but as with ordinary bikes, getting one of those can be difficult.
There is hostility from some push bike riders - most ebikers will have been called 'cheats' more than once, but in reality ebikes fill a gap in the market that allow the not so fit to enjoy a bike ride without the effort of a convention bicycle.
(
Adding a e-motor to a trike transforms it and makes it easier to ride uphill, It also helps with touring trikes that are laden with camping equipment etc.)
The above is intended as a general guide and is accurate as far as I am aware. Specific queries are probably best dealt with in separate threads where I - and others - can provide recommendations and opinions.
The website that caters solely for electric assist pedal cycles is the pedelec website.
The UK EAPC regulations are in the process of being revised. The 40kg for cycles and 60kg for tandems and trikes has been lifted and Electric assisted pedal quad bikes are being legalised.
Note: Thanks to @voyager for additional supporting information.
