Guide to electric bikes
Guide to electric bikes
What is an electric bike?
The simple answer is that an electric bike (e-bike for short) is more or less a regular bike with the addition of a motor to assist your progress.
The more complicated answer is that it is a hybrid form of transport meaning part of the power comes from the rider (exactly how much is up to you) and part of it from the motor. This applies up to around 15.5mph which is the current legal limit for electric assistance. Once you are pedalling beyond that speed the motor will not assist you.
You might also hear e-bikes called pedelecs. This is simply another name for e-bikes where the power is activated on pedalling instead of by throttle. The vast majority of today’s e-bikes are pedelecs – so clearly they are not really similar to mopeds or motorbikes as you must pedal to activate the motor (added to which, e-bike motors are much less powerful than moped motors).
Why would you choose an e-bike?
E-bikes are capable of doing just about everything a regular bike can do and more. So it may be you can extend what can be achieved through cycling, whether it be touring, leisure riding or daily commuting and chores, and gain a whole new experience in the process. Even e-bike sceptics often come back with a smile on their faces and appreciative words once they have actually been persuaded to step astride an assisted machine.
E-bikes are are also in a very privileged position legally speaking, as under the relevant European law (now applying in the UK – technically speaking ‘harmonised’ with UK law) they are in exactly the same legal position as non-powered bikes, so they bring all the well-known advantages of bikes but without any of the red tape normally associated with motor power.
As well as the obvious benefits of a motor – helping you get up the hills more easily and with less sweat – there are several other benefits that might not at first occur to you.
- If you have a recurrent injury or illness e-bikes may help you keep cycling through it, rather than having to give up pedalling completely.
- E-bikes fill the gap between journeys short enough for walking or non-powered cycling and longer trips where a train or car may be necessary.
- You could get to and from work faster on an e-bike and convert commuting into leisure time.
- They can be a viable replacement for a second car with all the environmental, financial and other benefits that this entails.
- E-bike riders often say they feel safer in traffic than when riding a non-powered bike, as the extra acceleration and speed up hills mean the speed of other passing vehicles is less than it otherwise would be. The quick acceleration off the mark also means you can clear stationary traffic more quickly.
- You can carry heavier loads more easily than with a regular bike, so many shopping trips and the school run might now be a possibility with an e-bike.
- You still get exercise – it’s not cheating! Many studies have shown that e-bikers get plenty of very beneficial aerobic exercise. The vast majority of e-bikes have power level settings on the handlebar controls that let you dial down the power if you want more exercise, or turn it up if in need of more assistance. Some even have a display linkable by Bluetooth to a heart rate monitor, to display your heart rate and calories burned.
- They are great fun to ride!
There are downsides compared to regular bikes; extra weight is the most obvious (although newer systems just emerging promise lighter e-bikes in the future). Writing in 2018 sub-20kg (including battery) is considered a fairly light e-bike. Modern motors are generally very reliable but today’s batteries should really be regarded as consumables if you plan to ride your e-bike a lot and keep it many years. They inevitably degrade slightly with time and more so with heavy use (and much more so with abuse), with a likely replacement cost of several hundred pounds. A good quality e-bike is a sizeable investment – but is that really a downside if you use it to its maximum potential, which is considerable?
How has e-bike technology improved over recent years?
Having just given a battery warning it has to be said that batteries, once the real Achilles heel of e-bikes, are now pretty much ‘fit and forget’ for a good number of years on good quality machines, as long as you look after them with a modicum of care. It’s just that, ultimately, they will need replacing. By contrast a good motor may well outlast you.
The other big development of recent years has been something of a motor power arms race between the major motor manufacturers such as Bosch, Brose, Shimano and Yamaha. Motors on e-bikes are legally limited to a maximum of 250 watts ‘continuous power’. This is a scientifically hazy definition and the peak powers of today’s motors reach many times this (for brief periods only). In practice this means quicker hill climbing and better acceleration.
Perhaps more helpful are the % assist settings on motors which are normally detailed in the bike spec. A lowest power setting can add around 40% of your pedal effort whilst on the most powerful motors top settings more than triple your own power input at the pedals!
However, don’t run away with the idea that today’s motors come anywhere close to those found on even fairly modest mopeds in terms of horsepower. Power delivery on the best quality electric bikes, usually delivered via a clever device called a torque sensor is smooth and seamless. Modern e-bike motor power is felt most in terms of quick acceleration up to the legal assisted limit of 15.5mph.
Different types of e-bikes?
There are almost as many variations of e-bike as there are regular bike. Here are a few examples of the various genres:
Probably the most popular class as they are suitable for a variety of uses including commuting, leisure rides and daily chores.
Gazelle produce a nice range of ‘sit up and beg’ e-bikes as you might expect of one of Holland’s best known manufacturers of quality bikes. Their PUUR NL+ has all the typical features of a Dutch town bike par excellence; rear and front racks for plenty of carrying ability, low step-thru height, fully enclosed chain and hub brakes. No special clothing or ‘extras’ needed, just get on an ride.
Kalkhoff make some of the most stylish commuters using their own brand of motor. Their Integrale model might be termed a modern sports commuter with a frame integrated battery and a crank motor that blends nicely into the bike’s frame lines. Also it has one of the biggest capacity batteries out there.
Of course, there is a huge variety of commuting e-bikes as just about all the quality e-bike makers have city and commuting versions.
E-mtbs – electric mountain bikes – are growing hugely in popularity as people discover how a bit of electric assist really comes into its own off-road where the going can get very tough. Haibike are probably market leaders but other choices include:
Giant, who use a totally remodelled Yamaha PW-X motor that is getting very good reviews on their Dirt E+ range
Scott who use a variety of crank drive motors on their range of e-mtbs including the very quiet Brose and the highly-regarded Shimano Steps.
Not e-mtbs, but suitable for trails and dirt tracks and ideal for long distance off road touring, are many of Riese & Muller’s extremely distinctive and immensely strong e-bikes. Take their New Charger model; capable of carrying 160kg rider and luggage weight and with the option of R&M’s dual battery technology to take battery capacity up to 1000Wh.
An ideal use for extra power allowing you to move what couldn't be moved easily by bike otherwise. Leading brands include Riese & Muller and Urban Arrow.
Well-engineered, portable brands are rarer than you might think. Brompton have set back the launch of their own model but well-made Brompton retrofit kits are available from the likes of ARCC and Nano.
Speed-pedelecs are capable of 45kmh / 28mph assisted speeds but as they not, legally speaking, e-bikes but mopeds we consider them in our separate article on e-bike law.
Types of motors
E-bike motors fall into two main categories; crank (or mid) motors and hub motors. Today crank motors are by far the most popular and are usually easily recognisable as a significant addition to the bike frame’s normal shape around the bottom bracket area. Their ability to maintain their power over a range of speeds have been at the heart of their success.
However, hub motors still have a place. For the budget-minded hub motors still tick many of the boxes; they provide a decent amount of assistance and the fact they don’t need a special frame manufacturing mean they can be retrofitted as kits to many kinds of ‘regular’ bike – perhaps an old favourite that is just in need of a boost to keep you using it. Small hub motors can also be very light and there are options to fit in the front or rear wheel.
Just as important as the motor type is the method of power delivery; better motor systems use torque sensors to ensure the motor responds to the amount of pressure you put on the pedals. Budget systems with motion sensors don’t feel as intuitive, as the as the motor simply kicks in in response to pedal movement.
Just about every e-bike sold today is based on some kind of lithium chemistry as this offers the highest energy density of all the different ‘flavours’ of battery. Early e-bike batteries were very heavy lead acid and these were succeeded by nickel metal hydride and nickel cadmium but soon manufacturers settled on lithium as it simply gave the most mileage.
Battery range varies enormously; the same e-bike with the same weight rider can produce huge range differences if ridden over different terrain and in different weather. Bosch’s handy Range Assistant gives an idea of all the variables at play and the huge impact on range they can have.
Having said all that, around 20 miles would be a minimum range expectation from a standard size battery of around 500 watt hours capacity ridden on full power over extreme terrain. A lightish very efficient e-bike with a lightish rider ridden on lower power settings and a 600Wh plus battery could exceed 100 mile range. Of course, spare batteries are available and can be carried with you to extend range.
It’s advisable not to run out of battery power as most e-bikes are hard work to pedal without power over anything but the easiest terrain.
Charging the battery is usually possible either on or off the bike and typically takes several hours.
However, it’s advisable to remove the battery when the bike is not being ridden for long periods and on cold nights. Cold temperatures and physical knocks are two factors that can decrease battery life.