I thought some people here might find it useful, so I've brushed it down and updated it:
What to look for when buying an electric bike
Written by Mike Boxwell
Not all electric bikes are the same and if youÃ¢â‚¬â„¢ve never tried an electric bike, here are a few pointers to help you identify which is the right bike for you.
Know the law
The law defines an electrical pedal assisted cycle (EAPC) as a pedal cycle with a small electric motor to assist the rider.
Maximum powered speed of the cycle is 15mph and the maximum motor power is 200w continuous output (250w for a tricycle).
The maximum weight for the electric bicycle is 40kg (60kg for a tricycle) and this weight includes batteries.
In addition, an electric bicycle must conform to normal bicycle construction and use regulations.
Electric bicycles are regarded in law as a bicycle and not a motor vehicle. As such, any electric bicycle conforming to the above definition can be used without insurance, tax, MoT certificate or safety helmet. The only caveat is the rider must be 14 years old or over.
When you are buying an electric bike Ã¢â‚¬â€œ especially if you are buying across the Internet Ã¢â‚¬â€œ make sure the electric bicycle you are buying conforms to these regulations. A surprisingly large number of them do not and this could have serious repercussions for the owner: buy an electric bicycle that does not conform to the EAPC legislation, and you can be prosecuted for driving an un-roadworthy motor vehicle without tax, insurance, and MoT. Have an accident in an electric bicycle that does not conform to EAPC legislation and you face prosecution with a likely prison sentence at the end of it.
Power, power and more power
Electric bikes arenÃ¢â‚¬â„¢t exactly the most powerful vehicles on the planet, but there is huge variance between different bikes available. By law, power output on an electric bike is limited to 200w, although voltage isnÃ¢â‚¬â„¢t specified.
As a rough rule of thumb, higher voltages equate to more torque and better performance. That isnÃ¢â‚¬â„¢t always the case though: electric motor performance varies considerably from manufacturer to manufacturer and some of the better designed bikes perform better on a 24v system than the cheaper bikes do with 36v electrics.
Most electric bikes have hub motors built into either the front or rear wheel. In general terms, rear wheel motors tend to be better, both for bike balance and also for low speed manoeuvring. In most instances, the hub motors themselves are single geared, so even if you can change gears on the bike itself, the gear change will only affect your pedalling, not the electric motor.
There are one or two exceptions to this rule, and the benefit of having a geared motor is improved hill climbing abilities. However, the difference tends to be slight, and for most owners this benefit is outweighed by the reduced ease of use.
Gears, or No Gears?
A lot of electric bikes do not have gears at all. The reason for this is simple: gears can actually get in the way on an electric bike.
When you pedal off from a standing start, the electric motor will cut in and help you accelerate. As a result, a very low gear is rarely required. As you accelerate, the electric motor continues to help you, meaning you can often be in the wrong pedal gear as you try to keep up.
Many people who own an electric bike with gears say that they rarely take the bike out of top gear Ã¢â‚¬â€œ the motor providing all the acceleration they require.
There are exceptions to this rule:
if you are cycling in hilly areas, buying a bike with gears will help you up the steeper bits
If you wish to travel at faster than the 15mph speed provided by the motor, a higher gear will make this easier to achieve.
How does the electric motor work?
Many electric bikes will only provide you electrical assistance when you are pedalling. These bikes (known as Ã¢â‚¬ËœpedalecsÃ¢â‚¬â„¢) have been built for the European market where electric bikes must be pedalled for the electric motor to cut in.
In the UK it is legal for the electric motor to be powered independently, using a motorbike-style throttle control on the handlebars.
Some budget electric bikes also do not allow you to pull away with electrical assistance. With these bikes, you have to pull away first and then the electric motor will cut in at above 2-3mph. Avoid these bikes Ã¢â‚¬â€œ much of the benefit of an electric bike is in having assistance when pulling away.
Ideally, you need an electric bike that will allow you to either power the motor either through the pedals or through a throttle control, and that provides power from the moment you pull away.
There are a number of different brake technologies now available for electric bikes. These range from the traditional Ã¢â‚¬ËœVÃ¢â‚¬â„¢ brakes as found on most bicycles, through to band brakes, drum brakes and disk brakes.
At the front of the bike, disk brakes are the most efficient, with Ã¢â‚¬ËœVÃ¢â‚¬â„¢ brakes also providing good braking characteristics in good weather. At the rear of the bike, disk brakes are also the most efficient, but drum brakes or Ã¢â‚¬ËœVÃ¢â‚¬â„¢ brakes can also work well. Avoid the band brakes used by a lot of the cheaper electric bikes. They tend not to work at all well.
Band brakes and drum brakes are not particularly efficient on the front of the bike as they do not provide enough initial Ã¢â‚¬ËœbiteÃ¢â‚¬â„¢ to slow the bike down quickly at speed.
The biggest disadvantage of the traditional Ã¢â‚¬ËœVÃ¢â‚¬â„¢ brake is that they do not provide good braking in wet weather. If you are going to be commuting all year round, it is worth choosing an electric bike with front disk brakes in order to get around this problem.
If you are travelling for more than one or two miles, it is worth considering an electric bike with some form of suspension Ã¢â‚¬â€œ or at least with reasonably large wheels which can absorb the worst of the bumps.
Suspension has been frowned upon by certain members of the cycling fraternity for years, as the suspension itself reduces the efficiency of pedalling. However, with electric bikes this is not an issue in itself, and suspension can make a big difference to comfort Ã¢â‚¬â€œ especially if cycling regularly over uneven surfaces.
What is more important Ã¢â‚¬â€œ Performance or Ease of Use?
An important question to ask yourself! If you are looking for an electric bike that is easy to use and maintain, choose a single-speed electric town bike. They are simple to use, require very little maintenance, typically have a good carrying capability with front basket and rear storage options and are effortless to use.
If you enjoy pedalling and want a performance electric bike, choose a bike with gears. YouÃ¢â‚¬â„¢ll go faster because youÃ¢â‚¬â„¢ll tend to use the electric motor to help you accelerate and pedal to go faster than the 15mph allowed by the electric motor.
If you enjoy pedalling, make sure you choose an electric bike that is easy to pedal, such as a touring bike or town bike. Folding bikes with small wheels are relatively low geared, making them easy to pedal up hill or when pulling away, but making the pedals virtually redundant at speed.
There are a number of different battery technologies available for electric bikes. These are Lead Acid Gel, Nickel Metal Hydride and Lithium Ion.
Until recently, Lead Acid Gel (LA) batteries were on the vast majority of electric bikes and are still the most popular battery technology for low cost bikes. The benefits of these batteries are reliability, range and price. The major disadvantage is weight Ã¢â‚¬â€œ it is not uncommon for the batteries themselves to weigh as much as 30% of the overall weight of the bike.
Lead Acid Gel batteries tend to last around 250-300 recharges before they need replacing, and so the cost benefits of buying the lower cost batteries can be outweighed by the number of times you need to replace them if you intend to be a regular user.
Nickel Metal Hydride (NiMH) batteries are much lighter than lead acid gel batteries. They will also last a lot longer before requiring replacement. However, the disadvantage is that unless they are properly maintained, range will decrease thoughout the lifetime of the battery and overall range may be less than an equivalent lead acid gel battery. Replacement costs are approximately twice that of lead acid gel batteries.
Lithium Ion or Lithium Polymer batteries are exceptionally light Ã¢â‚¬â€œ often weighing less than one kilo. TheyÃ¢â‚¬â„¢re not cheap, but performance is good, they recharge quickly and theyÃ¢â‚¬â„¢ll probably outlast the rest of the bike! If youÃ¢â‚¬â„¢re planning to use your electric bike a lot, lithium-based batteries are the ones to go for.
Just as important as the batteries themselves is the positioning of the batteries on the bike. A lot of electric bikes have their batteries on the front crossbar or on top of the rear wheel. This means the batteries are fairly high up on the bike and can give the bike an unbalanced feel. Other bikes have the batteries low down in the frame, below the seat. This is the preferred position for most riders: the bike has most of its weight low down in the frame making it feel more balanced, whilst the longer-wheel base makes for more relaxed cycling.
Most electric bikes come with a poor choice of tyres. In many cases, the tyre quality is not very good, in other cases they are simply the wrong type of tyre to get the best out of your electric bike, so if you're planning on buying an electric bike, budget for a tyre change in order to get the best out of it.
Mountain bike tyres can reduce the range of your electric bike by up to 20%, so replace them with good quality road tyres, preferably with puncture protection. My personal preference is Schwalbe Ã¢â‚¬ËœBig AppleÃ¢â‚¬â„¢ comfort tyres. They have puncture protection, are fairly grippy and have the real benefit of cushioning the ride, making journeys much more relaxing and enjoyable.
When you get your electric bike
If you havenÃ¢â‚¬â„¢t been using a bike for a while, make sure you get some practice on quiet roads. Read up on the Highway Code and get your confidence before facing busy traffic. Find out where your local cycle routes are Ã¢â‚¬â€œ you will often find that the journeys you do all the time can be done on cycle paths and back roads, avoiding the mainstream traffic completely. Not only is this safer for you the cyclist, but it also makes your journeyÃ¢â‚¬â„¢s out far more enjoyable.
Finally, don't forget to have fun! Electric bikes are hugely enjoyable and an easy way to get some gentle exercise. Most electric bike owners end up using their electric bikes almost every day and for many people they're now used as their main form of transport instead of using the car.