Guide to Buying an Electric Bicycle
If you have decided to buy an electric bicycle, that’s great. I’ll do my best to help you.
If you are just curious or thinking you might buy an e-bike think about reasons like saving money, enjoying life, but above all think of an extra 10 years of good and happy health and good mobility, and that’s priceless. I have pages here to add a bit of gentle persuasion.
In case you did know realise it, you can DIY convert most bikes to be electric bikes. There’re many YouTube videos about doing that.
2nd hand e-bikes on e-bay, garage sales and ads.
As increasing number of e-bikes become a few years old there will be more 2nd hand bikes for sale.
These will be cheap but beware that the battery may need to be replaced. It is quite likely that the main reason that the bikes are for sale is because of the expense of getting a battery replacement. As batteries get older the distance they can take you gets less. An old battery can be charged and “going” but will die in a short distance.
So if the bike is “going” make allowance for replacing a battery, and find out from where you can replace it. If the bike is not “going” do make a good assessment of what will be needed. If you can’t do that talk to someone who can.
Replacement parts, especially batteries and controller
These are the parts most likely to fail, and also the parts most difficult to replace. Some batteries are quite “generic”. That is their shape and means of fixing is the same for some different bike brands. These are easier to replace even if some things such as input and output sockets are different. Some batteries are specific to a bike brand. (That is a battery has to be a battery FOR that bike.)
Imported e-bikes are imported with a battery installed in the bike of course. Replacement batteries are expensive, and quoted prices vary a lot. Importing batteries by air freight is expensive, and an importer has to order many in a shipment or pay a premium for one or a few.
You should ask whoever sells your bike these questions about replacement batteries :
- are they generic or specific to the bike?
- are there replacements in stock, or available quickly, and what do they cost?
Controllers for the motor are usually different from one brand to another, and often from one model to another. They look similar but there are very many different arrangements of the sockets for the many wires coming from and going to them. I know this is a problem because many people ask me for a controller for a bike they bought from somewhere else.
A motor should last many years. Unless it is a unique design they could be replaced by a similar generic motor.
Other electric parts, throttle and brakes, are usually generic and replaceable.
The non electric parts are usually replaceable by any bike shop, though many bike shops are loathe to fix e-bikes (that will change).
Is the bike legal?
On the road power must be less than 200 watts, or 250 watts if it has no throttle.
A fueled motor must be registered as a moped.
Last year Australia changed its E-Bike rules to match those of Europe.
The effect of the new rules is that :
- Bikes already in Australia that comply with the old rules can be used.
- E-bikes now cannot have a throttle independent of pedallling.
- Pedalling faster than 6kmh is necessary and assistance must cease at 25kmh.
- Allowable continuous power output is increased from 200 watts to 250 watts, subject to those provisos.
Electric Bicycle Frames and Styles
Selecting an electric bike to buy is no different to selecting an ordinary bicycle, except that they have a motor to help you and some controls for the motor.
You should keep in mind your preferred style of riding and what you will use the bike for.
Heavy or light?
This is the major factor. A light electric bike weighs about 21 Kg. A heavy one weighs about 38 Kg. That is a big difference, and it is very noticeable.
Why such a difference? The main reason is the battery. A 36v lead-acid battery weighs about 14.5 Kg and a 36v lithium battery weighs about 4 Kg.
Bikes with lithium batteries usually have a light aluminium alloy frame.
Bikes with a lead-acid battery usually have a heavier steel frame.
All electric bikes are heavier than a similar non electric bike would be. The battery and motor are quite heavy. Usually about 9 Kg.
E-bikes with lead-acid batteries.
They make a lot of electric bicycles in China. More than 25 million each year! But about 90% of them are heavy bikes with lead-acid batteries. Why ? Because they are cheap, very cheap in asia,
so nearly all electric bikes there are the heavy ones.
Several million of the lighter electric bikes get exported to the rest of the world – because that is what they prefer there.
I used to have both types but found that if I offered two similar style bikes side by side : one heavy, and one light, customers preferred the light ones – at twice the price. So, I don’t have the heavy ones any more. Very few people wanted them.
There are some heavy e-bikes about. Any new electric bike selling for less about $700 is probably a heavy one (a 36v lithium battery costs about $400). They are cheap but heavy.
A warning about their batteries. They don’t last as long as lithium batteries. The battery case will probably be specific the the brand of bike. If so, the case will probably be hard to replace unless the place you buy it from has spares. If so and if you need to replace the battery you will probably need to replace the batteries within.
The batteries inside are 12v brick shape batteries wired in series.
The 12v batteries are very cheap in China, and are imported installed in a bike. Replacements can be bought at autoparts and battery shops, but are much more expensive to buy in Australia.
They are much smaller than a car battery but not so much cheaper.
Lightweight electric bike frames
The frame shapes of electric bicycles are similar to those of ordinary bicycles. You can get (just about) whichever type suits you…
(If you don’t know which that is, you should try a few friend’s bikes).
If you sit and watch the stream of bikes in Amsterdam, or Copenhagen, or other big bikey european cities you will see that nearly all the bikes are “city” type bikes and that the riders are sitting upright. I think that as more people here adapt their ways to bike riding “city” style of bike will become more common than “road” or “mountain” bikes, especially for short rides, or commutes.
Of course anyone who has difficulty get over a frame with a high bar will like the city or “step through” frame.
If you are very style conscious there are some very stylish, and very expensive, electric bikes coming from european designers…and some cheaper California inspired “cruisers” from China.
Also worth considering are folding electric bikes, which are most commonly “city” style with smaller (20″) wheels.
Folding Electric Bikes
I am finding that folding electric bicycles are becoming much more popular because many people either do, or plan to take the bikes on their travels in their car, or mobile home.
They can stow them easily and don’t need an expensive bike carry rack. Not only that but they stow away in home or office and can be taken on a lot of public transport. Those who
“don’t like” folding bikes can just forget that they do foldup until they need to be folded up.
Range – how fare does an e-bike go?
The energy available (which translates, other factors being equal, to how far you can go) is proportional to voltage V of the battery X the Ampere-Hour (AH) of the battery. The most
common combination is 36v and 10AH and this battery is suitable for motors up to 500 watts.
There are some 24v 250 watt electric bikes, which are 1 or 2 kg lighter but have range about 2/3 of the 36v bikes.
As a rough guide a 36v battery in a 250w electric bicycle going about 25kmh should go about 35-40 km.
The bike factories in China quote a “range” for their bikes, and bike shops generally quote that range in their description. I find that this quoted range is usually quite optimistic – possibly because they assume people will extend the range by pedalling.
Of course, you can extend the range by pedalling, and I hope you do, and get that beneficial exercise, but comparisons should be made on what the is range with battery alone.
There are many factors that affect the range of a bike. These are mentioned in Notes below.
Electric bicycle motors
The cheap and heavy electric bikes common in asia usually a have brushed motor.
Brushed motors are a little bit cheaper. The lighter more expensive electric bikes would now have “brushless” DC motors, commonly called BLDC.
There are 2 types of BLDC motor – larger diameter motors that are (internally) ungeared and have power from 300w to 1000w, and more compact motors have internal gears (that make a low whirring sound) and have power up to 300w. The bigger ones are about 2kg heavier and run more silently.
Bikes, and conversions, can have motor power from 200 watts to 1000 watts. The higher power 1000w motors should (sometimes must) have 48v battery.
Depending on what country you are in anything above 250w may be illegal (on a road).
In Australia, for instance, the legal limit is 250w whereas in US it 750w, and other places are either in between, or don’t care.
There is some confusion about the “watts”. The chinese suppliers quote the motor’s power as watts of “input” and most bike shops repeat the input watts in their description of the e-bike. The authorities regulating these are concerned about “output”.
This matters particularly in australia where the limit is 250w “output”.
Electric motors do not have a fixed upper power limit and the output power can exceed nominal power. A higher voltage gives higher power. All motors are somewhat inefficient, ie they lose energy between input and output, and the electric motors are at best 80% efficient.
The cost difference between low and high power motors is very little, but the cost of batteries to support them does vary – roughly in proportion to V x AH, higher V and/or AH being needed for high power motor.
What power of bike would be suitable for you?
For most people and most purposes – that is travelling about 25-27kmh on ordinary streets and roads in ordinary suburban terrain a 250 watt bike is quite adequate.
Suggestion : If you do ride an electric bicycle that has more power than is allowed, do, at least, pretend to be pushing on the pedals.
(Better still, do push on the pedals, and get that very beneficial exercise)
For comparison between your efforts and the bikes’s power – 250w is about what you can produce if you are reasonably fit. If you are a competition road cyclist you could put out twice or more of that- but you wouldn’t want to go electric would you?
(If you are on a 500w bike and overtake a road cyclist on a hill please be polite.)
The cost of an e-bike?
The prices quoted for electric bicycles varies a lot. Generally $1300 to $2500 for an alloy frame, and about half that for a steel frame.
The Chinese are not concerned about recommended prices so beware of any fictitious “save $$$” on RRP. (nothing much sells for recommended price these days anyway)
Compare like with like. The quality of components varies a lot…within China, and more so when they use parts from Taiwan instead of Chinese parts.
Compare frame features such as whether the fork has dampers, the handlebar post is adjustable. Compare also quality of, or presence of items such as basket or rear rack, front or rear lights, seats, mudguards, chainguards, tyres and tubes (brand, thorn resistant, reflecting strip). The cost difference between a good and inferior – say pedal or seat – is not a lot in China, but they do try to have a cost advantage over one another rather than a quality premium, so look for quality parts.
Batteries are the most expensive component in an electric bike, about 40% of the total.
There has been, and I believe still is, a very big difference in the performance of batteries between the many places that make them.
Eventually I hope the lesser quality ones will get weeded out, and the better quality makers will increase business. The batteries all look the same, but one doesn’t know how long or how well they will go until they have, or have not, done or gone as they should.
There are several formulations generally called “Lithium-ion” or “li-ion” and others with LithiumIronPhosphate (or LiFePO4, or LFP) cathode.
The li-ion and LFP batteries are usually quoted as having a “life” of 800 and 2000 charges respectively. This quoted “life” comes from the battery supplier who may (or may not have) at some time done a test on a battery. Such test would have been done by rapid repeated charge/discharge cycles until the battery’s energy was reduced by 20%.
In practice, in real use, you may get half of that, but in any case the LFP batteries should last twice or more as long as li-ion batteries because they are much more resistant to the things which degrade all lithium batteries, vibration and shock, (especially) heat, and time itself.
LFP batteries are not common (probably because of cost saving by the factories), but are becoming more common. Even though the energy contained is a little less than in a same size li-ion battery and that they cost more it is worthwhile getting LFP batteries.
However, LFP is a bulkier cathode and any size of battery will contain less of it (and thus energy/distance) than a similar sized battery with Li-ion. For instance 11AH Li-ion and 9AH LFP are often the same size and A 10AH LFP battery will be taller than a 10AH Li-ion battery.
Outside of Europe (where they can’t have one) electric bikes will most likely at present have
a hand throttle. There may be some now, possibly made for europe, that don’t have a throttle.
These will have “pedal assist” or PAS. With this starting, or stopping, pedaling turns the motor on, or off. An improvement to PAS, which many bikes have now is selectable amount of “assist” which you can vary by a handlebar mounted electronic device.
Many bikes will have both PAS and throttle. And that’s nice…but maybe illegal.
And now a word about how the “assist” works.
It does not matter whether your bike is powered by the front wheel or the rear wheel, you can add your own effort to the going, but only if you “get ahead” of the motor, whatever speed it is going. What I mean by that is that you need to pedal faster than you would to go at the same speed if the motor was not working. When you do that you put some tension in the chain. The motor “notices” that and reduces its output.
The more effort you make the less the motor makes until it feels it is not needed, and then you will be doing all the work.
All electric motors have a maximum possible speed, and an optimum efficiency range (rpm) about the middle half (about 1/4 to 3/4 of the maximum) within which they will be operating close to their maximum efficiency. On hills at speeds lower than about half the maximum speed it is best if you add enough power of your own to maintain that speed (using the gears). If the motor slows down and “struggles” it will be sucking a much larger current from the battery. This will shorten life of the battery, and may cause the controller to burn out.
Benefits to you? A lot!
If you need convincing think of the benefits…
Good for the environment, and saves you money, and most important of all – good for YOU!
Whether you go for a walk, or ride a bike, a small amount of daily exercise has a huge effect on your health, fitness and happiness in later life, and has been shown to add years to your life compared with a sedentary and sitting down lifestyle.
A win-win for all, don’t you think? Go find a good electric bike, and start enjoying it!
Gears, or not for an e-bike?
Most electric bikes have at least 6 gears and one chainwheel cog.
Most of the time (if the power is on) you won’t need more than the top gear or two anyway.
Unless you will be a serious unpowered cyclist some of the time you won’t need 18 or more gears – 6 will be more than enough.
Generally the smaller 250W motors will have maximum speed on flat streets of about 25-27kmh.
A 500W motor would travel about 5 or 6kmh faster (not twice as fast). The maximum speed is not directly proportional to power, but is more closely proportional to power when climbing hills at slower speeds. (Because wind resistance increases rapidly at higher speeds and eats up the extra power, whereas the energy needed to fight gravity is proportional to speed).
The range of an electric bike depends on…
The bike, the battery, the terrain, the ride, the day, and you, it’s rider :
- 1.The bike….it’s weight, its condition, whether the tyres are fully pumped, and whether the wheels spin freely, and the brakes don’t drag.
- 2.The battery….its voltage, its AH, the ampere-hours, and its age…(the product of the V and the AH is watt-hours, and that is the energy available to make the bike go, although there will always be some energy left that can’t be used). The capacity of any battery reduces with its age (more so with li-ion, less so with LFP).
- 3.The terrain….hills have a very big effect.
- 4.The ride….the speed, the stopping and starting. Any use of brakes destroys energy that first came from the battery and has to be replaced to get going again. The distance that you would have gone if you coasted to a stop is that much less range – possibly up to several hundred metres. The get-going reduces range because the motor is inefficient at low speed. At full speed the range could be a third less than it would be at around two thirds of max speed – because the efficiency of the motor is much less when it is running close to its maximum speed.
- 5. The day….less if it’s windy, or very cold and
- 6 you, the rider…how much effort you contribute yourself – As a guide, a fit cyclist could sustain about putting out energy of about 200W, and the more energy from you the less is needed from the battery.
Tips for getting a greater range from battery.
- 1. keep tyre pressure up (this also reduces the chance of a puncture)
- 2. accelerate slowly, and
- 3. anticipate stopping and use the momentum to glide to a stop.