Common E-bike Battery Problems and How to Fix Them
There’s nothing worse than having to spend hundreds or thousands on an eBike only to have problems with its battery. Don’t get me wrong; e-bike batteries are built to last. but they’re still prone to failure if they aren’t adequately taken care of during their lifetime.
What happens if your battery fails?
Well, in this article, I’ve covered some most common eBike battery problems and how to fix them. So, if you’d like to know more. keep scrolling!
Ebike Battery Problems
When it comes to eBike troubleshooting, there are a couple of things that might be causing your battery problems, including:
- eBike battery pack swelling
- eBike battery not charging
- eBike battery not running for very long
- eBike battery pack not holding a charge
- eBike not turning on
- eBike not speeding up
Don’t worry, though. I’ll walk you through each one here!
eBike Battery Pack Swelling
If your eBike battery pack is swelling up, well, you likely have a pretty serious problem with one. or more. of the lithium-ion cells.
Some electric bike models use flat pack cells. and these are known to swell if they suffer some damage. On the other hand, the 18650 lithium-ion cells are far more resistant to swelling and, in turn, more reliable.
If you notice that your eBike’s battery pack has a bulge in it, be sure you turn off the power and carefully remove the battery from your eBike. It’s a good idea to recycle the battery; most cities have a place where you can do this.
Now, some eBike battery packs are positioned inside the bike’s frame. That makes it somewhat harder to notice if you have a swollen battery pack.
The only way to check if the battery is swollen is to drop the lower plate and take out the battery pack. Note that you’ll have to disconnect some cables before you do this.
eBike Battery Not Charging
If your battery isn’t charging, start by checking the following:
- Is the power turned on at the outlet?
- Is the charger working and outputting over 36 Volts?
- Is the battery hot?
- Is the battery charger port full of dirt?
- Has the battery been left discharged for several months?
- Has the fuse blown in either the eBike battery pack or the charger?
eBike Battery Not Running For Very Long
Lithium-ion batteries generally have a life of 700 charge cycles. They usually tend to lose full charge capacity over this mark.
That is entirely normal. and will, unfortunately, only get worse as time goes on.
Still, if you’re charging your bike every few days, you should be able to get many years out of your electric bike before you begin to notice the capacity of your battery is starting to degrade.
If you notice your eBike battery isn’t running as long as it used to, check the following:
- Is the battery pack being charged to 100%?
- Do you have a dragging of a disc brake?
- Is the terrain uphill?
- Are you assisting your battery by peddling?
- Are your eBike’s wheel bearings freely spinning?
- Do you have a short circuit in the battery, wiring, or motor?
Any of the scenarios mentioned above could lead to your battery discharging rather quickly.
eBike Battery Pack Not Holding A Charge
Lithium-ion batteries are good at holding a charge. However, like any other type of battery, they will slowly discharge over time.
If your eBike hasn’t been charged for a more extended period, it would be a good idea to give it a top-up. and see how it goes.
If you notice that you’re charging your battery, but it still discharges quickly without being used, you might have a short circuit somewhere or a faulty battery at your hands.
Here’s a quick test that can detect the problem:
Remove the battery pack from your eBike and charge it up on a bench. Once it’s fully charged, test the battery by leaving it off the bike.
If it holds a charge, the issue will be your electric bike. most likely a short circuit in the bike’s wiring or the motor. However, if it doesn’t hold the charge, your lithium-ion cell is faulty.
How Do I Know If My Bike’s Battery Is Charged?
Your battery charger will probably feature a LED light indicator that changes states depending on the bike’s battery level. It’ll go from red to green when the battery is fully charged in most cases.
However, in some chargers, the LED light will turn off completely when the battery is charged.
Either way, the point remains the same. you’ll have a way to track the progress while charging the battery.
Remember not to leave the battery pack on the charger longer than 24 hours, though.
Lithium-ion batteries don’t prefer being left on the charger. In the short term, this won’t hurt. but after a while, the battery’s capacity will go down.
You’ll also have an indicator of the battery’s current level on the battery pack itself or the speed controller. Some will use a 0-100% range, while others have a series of LED lights, depending on the model.
eBike Not Turning On
Let’s start with the obvious solution:
If your e-bike isn’t turning on, be sure to check if the main switch is in the “On” position.
Next, check the fuse for the battery pack. This fuse is usually located on the side and could blow up because of short circuits, vibrations, over-current, or old age.
If the fuse is in good condition and the battery pack is fully charged, check if the speed controller is in good condition, as well. The speed controller is the component that sends signals to turn on the battery pack.
These speed controllers could malfunction if damaged. either by dropping your bike or allowing water to get into them.
Hold the bike’s “On” button for about 10 seconds to force the speed controller to turn on. Some speed controllers are turned on by pressing the “M” button. Again, it depends on the e-bike model you have.
Be sure to check that your battery pack has at least two bars of power. An extremely low battery power level can lead to your electric bike not turning on, by the way.
Another thing to check here is that the electrical cables are correctly connected. Sometimes, the dirt roads can dislodge the cable connections; this is often the case with mountain electric bikes.
Water can find its way into these connections, too. Pull them apart and ensure the connection is tight.
eBike Not Speeding Up
There are numerous reasons why your electric bike isn’t speeding up.
often than not, the feedback magnets. positioned on the pedal crank or the rear wheel hub. for the proximity switch get dirty. Clean them with a rag, and you should be good to go.
This common eBike battery issue is often wrongly diagnosed.
Most quality electric bikes feature a switch on the back and front brakes to stop the drive motor. In some cases, these switches can get stuck. leading to their failure. Activate both brake levers a couple of times to try and free up the switch.
To check the limit switch, though, you might have to remove the whole rear or front brake lever. That’s another reason why you should avoid leaving your eBike out in the rain.
Also, while it might sound obvious, be sure to check if you’re in the proper mode. for example, pedal-assist, throttle-only, or pedal-only. I’ve sometimes found myself in the wrong mode, and I couldn’t figure out why my eBike isn’t speeding up.
There is typically a minimum speed that will activate the drive motor. That is just a safety feature. and it’s usually around 1.8 mph.
What Speed Are eBikes Limited To?
eBikes are limited to 25 km/h. or 15.5 mph. to conform to the majority of road rules around the globe. Once the motor reaches this speed limit, it will stop providing power further.
Of course, you can still pedal faster than 25 km/h, but you won’t get any assistance from the main motor.
Once the speed controller recognizes that you’re under 25 km/h, the battery management system will again supply power to the main motor. That is a standard component on most electric bikes. and, again, its role is to ensure that you conform to road rules.
Is 250Watts Enough For An eBike?
In most standard cases of use, 250W is more than enough power for you to ride your eBike on asphalt or dirt roads casually. A 250W drive motor is usually limited to 15 mph and can handle up to 240 pounds in rider weight.
If that doesn’t sound impressive, remember that you can always assist the main drive motor by pedaling.
You can always upgrade your bike with a Bafang conversion kit, though!
Conclusion
We can agree that e-bikes have come a long way since their first appearance. Granted, battery problems can occasionally happen, but most can be solved easily and quickly.
Hopefully, the tips I’ve outlined above will help you keep your eBike running fast. and for a long time. And remember:
The most significant danger to batteries of eBikes is excessive heat and low voltage. Make sure you keep your eBike battery topped up. and it will last for a very long time.
Don’t Buy Another Gas Car! No Hybrids Either. It’s Got To Be Electric!
Your current car is getting a bit long in tooth and it’s time when you would normally be looking to replace it. Don’t buy another gas car! Some of you won’t let “them” pry a gas car from your cold dead fingers. However, many of the rest of us are open to the idea of an electric car. Some of you just don’t think one would work for you. If you are dead set on pulling a big boat 500 miles to Lake Powell on a regular basis, or taking a 45 ft travel trailer on a cross country trip, you are correct. However, for everyone else, an electric vehicle would not only work for you, but it’s a much better vehicle and you will love it. Besides, we are approaching the time when gas vehicles will fall out of favor, new sales will be banned or just fade away, and the resale value of your gas vehicle will drop to nearly zero. Ever try to sell a tube TV after flatscreen TVs had taken over the market?
17 Teslas at Supercharger in Beaver, Utah. December 26, 2022. Photo by Fritz Hasler.
The top two reasons for thinking an EV is out of the question for you are most likely these: you think there aren’t enough charging stations, and you think EVs don’t have enough range. If you buy an EV, your primary charging station will be in your garage. If you buy a Tesla, its fabulous Supercharger network along all the Interstate highways makes long-distance driving no more complicated than driving a gas car. Ford has just signed onto Tesla’s Supercharger network as well, so you are no longer restricted to buying a Tesla for a good long-distance travel car. With other brands, more planning is required for long trips. There are also backroad excursions far from the Interstate highways that would require some research and perhaps an overnight stay at a hotel with a destination charger. However, the federal government’s Inflation Reduction Act has 5 billion to upgrade the national charging network, so even that problem should go away over the next few years.
If you think range would be an issue, think again. Some electric cars, like the Tesla Model S, now have a range of more than 400 miles, which is much longer than most people’s preferred stops for bathroom breaks. There are also plenty of other brands now which have a range of longer than 300 miles, and almost every EV has a range of more than 200 miles. (If you drove 200 miles a day on weekdays and didn’t drive at all on weekends, that would be 52,000 miles a year. That’s about 4 times the national average.)
If you are thinking EVs are too expensive, think again. The full 7,500 federal government tax credit for electric vehicles is now available for the least expensive Tesla Model 3 (40,240), the similarly priced Volkswagen ID.4, (38,995 MSRP), and the even cheaper Chevy Bolt (26,500 MSRP) and Chevy Bolt EUV (27,800 MSRP). With the full federal government tax credit plus the state tax rebate (in many states), a Tesla Model 3 can now be 30,000 or less. In Colorado, the subsidy has just been raised to 5,000. So, in Colorado you can buy a luxury Tesla for essentially 27,000, only 10,000 more than a Toyota Yaris econobox.
However, note that you have to have a 7,500 IRS federal tax obligation in the tax year that you buy the car — or whatever your tax obligation is below that is your max tax credit. Also, you don’t get the refund at the point of sale — you need to wait to file your taxes. One way handle this if you have a good credit rating: put 7,500 of the purchase price as a charge on a credit card, and then many cards offer free balance transfers with 0% interest for up to 18 months for a new credit card application. Before the balance is due, you will have your tax refund and can pay off the credit card. If you lease your car from Tesla, you can get the government rebate at the time of sale.
List of electric vehicles on the market or coming soon
If you are thinking the model you want is not available, think again. In a quick survey, I found that 41 different models of EVs from 20 different brands are available this year in the US, with another two coming in 2024 and others later. EVs range from small budget cars as low 20,000 (with the government subsidy) to large sedans and SUVs that seat 6 or 7 people to full size pickup trucks from Rivian and Ford (and soon Chevrolet).
They now make the EV model you want and you may be able to stay with your favorite brand!
EV availability was a problem as late as last year, but the Ford F-150 Lightning pickup truck has been in production for over a year now, the startup Rivian has been making pickups for over a year as well, and many other vehicle types are available — almost all other vehicle types. Rivian makes a pure electric SUV on the same chassis as its pickup that is similar to a Ford Excursion or other large SUV. If you want to go with a traditional Tesla SUV, the Model X will seat 6 in three rows of captain chairs with plenty of foot room for adults in all rows. You can also get the Model X with seating for 7. Then there are smaller electric SUVs like the Ford Mustang Mach-E, Tesla Model Y, Nissan Ariya, etc.
See the EVs I found below that are available in 2023:
- Tesla: Model 3, Model Y, Model S, Model X, Cybertruck, Semi
- Ford: Mustang Mach-E F-150 Lightning
- GM: Hummer, Chevrolet Bolt and Bolt EUV, and Cadillac Lyric
- Rivian: R1S and R1T
- Volkswagen: ID.4
- Nissan: LEAF and Ariya
- BMW: i4, iX
- Polestar: 2
- Porsche: Taycan
- Mercedes: EQE, EQB, and EQS
- Audi: e-tron (various versions)
- Genesis: G80 and GV70
- Jaguar: I-Pace
- Lucid: Air
- Volvo: C40 and XC40
- Mini: Cooper SE
- Hyundai: Ioniq 5, Ioniq 6, and Kona Electric
- Kia: EV6 and EV9
- Subaru: Soltara
- Toyota: bZ4X
On the marketin 2024:

Available later:
- Tesla: 25,000 car and shuttle car
- Aptera: Hyper-low coefficient of friction, solar 3-wheel car with 500 mile range
details on charging an EV
Where will I refuel? Only farmers and rural residents can have a gasoline refueling tank on their property. Safety zoning laws prevent gas tank installations in cities. However, with an EV, you will do most of your refueling in your garage.
There are three levels of charging for EVs: Level 1 (L1), Level 2 (L2), and Level 3 (L3).
L1: Any normal 110V outlet anywhere. Obviously, these are much more ubiquitous than gas stations. However, L1 is very slow. You get ~4 miles of range per hour. 110V charging is useful only if you are able to take a day or two to charge your car. We have friends with a top-of-the-line EV who make do with L1 charging. They make cross-country trips using Superchargers, but they don’t do much local driving and have a second car.
Note: My Model 3 came with the EVSE cable needed to charge with a 110V or NEMA 14-50 outlet. New Tesla owners need to purchase a 200 Mobile Charging Cable.
L2: 220V charging that most EV owners have in their garage, carport, or driveway. When I took my EV to Northern Wisconsin for the first time, I called an electrician to see if I had 220V service in my standalone garage and to schedule charging installation — 20 minutes and 130 later, he had installed a NEMA 14-50 outlet in my garage and I was good to go. L2 charges your vehicle at ~24 miles of range per hour. If you have L2, you start every morning with a full charge. If you make a longer trip in the morning, you may need to charge for a few hours before doing it again in the afternoon. For local driving, your “gas station” is in your garage. It’s as easy as charging your cellphone. Also, you never need an oil change or emissions check. In Utah, your first mandatory state vehicle check is after 4 years for mechanical issues.
L3 (DC fast charging): L3 direct current charging ranges from 50 to 350 kW in the US. Tesla has over 1500 of its 150–250 kW Superchargers out there today, with 12,000 stalls spaced at 70 to 130 miles on all the major Interstate highways and in major cities in the US. A Supercharger will charge your Tesla from 20% to 80% state of charge in about 20 minutes. Note: I do 500 cross country miles per day in my EV (the same as I did in my gas-mobile). However, if you are driving “nonstop” across the country, an EV will slow you down a bit. Remember: The Tesla Model S has 405 miles of range and the rest of the Tesla lineup has versions with ranges of up to ~350 miles.
Why not a plugin hybrid?
At first glance, a plugin hybrid would be a good way you could gradually transition to an EV. With up to 50 miles of EV range, you could do 90% of your driving on electricity. You plug in at home and at work, and only on longer trips would you ever use gas.
A plugin hybrid is an especially bad choice for someone who doesn’t have easy access to charging at home and work. The buyer takes advantage of the government subsidy on purchase but may rarely charge the car and then it runs almost entirely on gas.
Double the powertrains, double the trouble. A big advantage to an EV is the simplicity of the electric motor drivetrain, and leaving all the complexity of an internal combustion engine behind. With a plugin hybrid, you get the problems that may arise with the electric drivetrain and battery plus you have all the fueling, oil changes, emissions inspections, and maintenance problems that go with a gas car. It doesn’t seem worth it.
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Arthur Frederick (Fritz) Hasler, PhD, former leader of NASA Goddard Space Flight Center Scientific Visualization Analysis Laboratory (creator of this iconic image), and avid CleanTechnica reader. Also: Research Meteorologist (Emeritus) at NASA GSFC, Adjunct Professor at Viterbo University On-Line Studies, PSIA L2 Certified Alpine Ski Instructor at Brighton Utah Ski School.
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Electric bike conversion kits 2023 – Give any bike a boost
Why pay for a brand new e-bike when electric bike conversion kits can easily give a boost to the bike you already have?
E-bikes have enabled people who need or want some pedal assistance to broaden the range and scope of their riding while making it easier than ever to choose sustainable and greener transport methods.
Whatever your reason for wanting pedal assistance — whether it makes cycling more accessible to you and your family, or you think you’ll have more fun with that boost. the e-bike market is vast and often requires a large upfront cost. So if you’re struggling to find an e-bike that suits you, and already have a bike at home, then you might consider an electric bike conversion kit instead.
Whichever option you go for, there’s no denying that the best electric bikes make it easier for riders to explore and experience different terrains and riding environments. Plus they offer a cheaper and greener form of transport to get you from A to B at a higher pace for less effort than a conventional bike, which is especially beneficial for those who are commuting or using them for work. The best electric bikes for commuting can make for a speedier and altogether less sweaty cycle to work, not to mention the money saved when compared to soaring fuel or rail fare prices.
But what if you’re not sure about which option to go for? If you’re weighing up an e-bike vs an e-bike conversion kit, consider whether you already have a bike that you love riding. Converting it means you can continue enjoying the same ride quality while introducing you to a new world of electrically-assisted fun.
To make all these decisions easier for you, we’ve outlined the key things to consider when fitting an electric conversion kit to your own bike, including the various motor and battery options available. We’ve tested as many as possible in real-world riding conditions, assessing how easy they are to fit, and what kind of electric assistance they provide.
So here are our findings, and our roundup of the best electric bike conversion kits you can buy right now.
Best electric bike conversion kits available now
You can trust Cyclingnews
Our experts spend countless hours testing cycling tech and will always share honest, unbiased advice to help you choose. Find out more about how we test.
Reasons to avoid
A thorough purchase process ensures the product is easy to install, but it’s complicated so can take time
The first on our list is one we reviewed very recently and which really impressed us. The Cytronex electric bike conversion kit is extremely well thought-out, with great specs and top-notch engineering. You only need Allen keys to install it, it comes with an accompanying app to offer up basic diagnostics, and once it’s set up it’s a breeze to operate.
When purchasing, you’ll go through a thorough process, which can feel a bit over-complicated, but in doing so it means the actual conversion is a straightforward one. We tested out the Cytronex on a Brompton T-Line and found it delivered smooth and intuitive power. Plus, our hands-on time with it leads us to believe it’s strong and durable enough to use for commuting.
While it’s pricier than some of the options listed below, one thing to consider is that it comes from a UK-based company that offers comprehensive customer support. You can pay less for a Bafang kit on Amazon, but buying direct from a company that can support you if anything goes wrong, makes it a smarter choice in our view.
For an in-depth look, check out our Cytronex review.
Reasons to avoid
One of the easiest ways to convert a bike to electric is to swap out the front wheel for one with a front hub motor. This is the approach that Swytch takes, but there’s more to a good system than just a motor and battery. From our time testing and reviewing it, it’s clear to us that the team behind Swytch have considered the whole system in its design.
The battery mounts to the handlebars and we found that a really useful detail. It is easy to disconnect and take it away for storage, so it doesn’t get stolen when you are out and about, or to lighten the bike when, for example, it needs to be carried up a flight of stairs.
The 2022 Swytch system, which we tested, makes use of a neat handlebar-mounted LCD display instead of the buttons on the battery it had before. There’s also a cadence sensor that attaches to your bike. It’s a well-thought-out system that looks and feels great.
To read all about how it works, and find out why we gave it four stars, take a look at our Swytch review.
Reasons to avoid
If you’re on a tighter budget than the Cytronex or Swytch allow for, then as we mentioned above, getting a kit from Chinese manufacturer Bafang may be a better option. Plus, if you like the idea of an electric bike conversion kit but just don’t want to have to deal with the added complexity of a mid-drive setup, then the Bafang Front Hub kit makes things much easier.
Like the mid-drive system listed below, the Bafang Front Hub Motor kit covers everything required and gives tons of spec choices. We started by choosing our wheel size and display preference, then added the battery size and shape we wanted.
We did find it more of a time investment, given the installation process was more complex than the Cytronex, Swytch and Rubbee, but this did allow us to achieve a powerful, high-quality set-up.
To find out more about how we got on, read our Bafang Front Hub Motor review.
Reasons to avoid
There are a number of simple install options on the list but the Rubbee X takes it a step further. We were really impressed with how easy it was to attach the mount to the bike’s seat post and then click the unit into the mount. There’s no need to change the wheel like the Swytch system. Here the motor sits on top of the rear tyre and a roller pushes it around from above. There’s also a wireless cadence sensor, as this is a cadence-based system that adjusts based on pedalling cadence, rather than torque.
There is a slick-looking 250-watt motor with a single battery in the base kit. If the 10-mile range of the base unit feels a little constricting, another battery can be added to double the range. Rubbee also has a handy phone app that can be used to change assistance modes.
We’ve spent some time testing it out, so why not check out our Rubbee X e-bike conversion kit review for more details.
Reasons to avoid
Bafang is one of the largest and most well-known electric bike motor companies in the world. It’s been around since 2003, and in 2014 Bafang established a US arm to better support the US market. There are many well-known electric bike companies sourcing its components, so if you want to get in the game and source your own electric bike components, you won’t go far wrong with Bafang.
This particular option covers everything you need for a mid-drive motor conversion kit. As long as the bike you are starting with has a bottom bracket sized between 68 and 73mm, this kit will work. From there you can choose the front chainring size, the battery size, and what display works for you.

If you’re not sure whether or not a mid-drive motor conversion is what you need (or what other drive options there are), head down to our FAQs at the bottom of this article for an explanation of all the possibilities you can choose from.
Reasons to avoid
The most natural-feeling electric bike conversion kits are going to be those with a mid-mounted motor. If that works for you and you also like the idea of doing some pedalling, then the very best is a mid-mounted motor paired with a torque sensor.
Instead of the system knowing you are pedalling and adding power, such as the Rubbee X cadence-based system above, a torque-based system adds a percentage of power. The Max torque available on this TongSheng system is 80Nm but depending on your chosen assist level, that 80Nm will add between 36 and 300 per cent to your pedalling power.
To keep it simple, think about it as an amplifier. If you pedal harder you go faster, just like a normal bike, but now your muscles have extra support, so you can go further with less effort.
Reasons to avoid
If you like the idea of a mid-drive system and you want it to have torque-sensing pedal assist then you’ve got a few choices. The challenge with a system like that is complexity. For some people, it’s no big deal to take apart a bottom bracket, but for others, it’s a slightly more intimidating prospect.
The Pendix system does the same thing as other kits but there is a dealer network that handles sales, support, and installation. This comes with an extra cost attached, but the benefit is that you can feel comfortable that the system is correctly installed and ready to ride.
Types of e-bike conversion kits
Friction drive conversion
A friction drive e-bike conversion means there is a roller that pushes against the wheels tyre. So when the roller turns, the wheel turns. It’s not the most efficient strategy, but it’s simple and it works. There is very little involved with regard to making it work but, at the end of the day, it doesn’t work as well as other systems out there. The Rubbee X is an example of a friction drive conversion kit system.
Mid-drive conversion
The best electric bikes tend to be mid-drive because this delivers the most natural ride feel, and the same is true of conversion kits. The weight sits low in the frame and the power gets applied to the crank for a more natural power delivery sensation. The only downside is pricing and packaging, plus it can be complex to set up yourself. Different standards make it challenging to figure out exactly what you need, as well. The Bafang Mid Drive Motor Kit is an example of this.
Electric bike wheel conversion
Swapping either a front or rear wheel for one with a hub-mounted motor is a good balance. The conversion process is very simple and, depending on how the battery mounts, the weight distribution can be quite good. Powering the wheel does change the way the power delivery feels, and making the front wheel heavy can affect the handling of the bike. If mid-drive seems overwhelming, this is an excellent option. Cytronex and Swytch are examples of this.
How to choose the best electric bike conversion kit for you
If you’re interested in fitting an electric bike conversion kit to one of your own bikes, you should consider your own personal requirements first and do plenty of research. You’re in the right place, as this guide will help you with a lot of that.
Before anything, familiarise yourself with the laws regarding e-bikes in your region. Then you may want to choose a conversion kit based on your range and journey needs. If you live in a hilly city, for example, you may want something with a little more top-end power. Lastly, check whether or not the system is compatible with the bike you plan to fit it onto. If you don’t feel comfortable doing this yourself, think about getting a quote for installation from a reputable bike shop.
Do all electric bike conversion kits come with a battery?
The short answer is ‘not always’. You need a battery, of course, so when browsing online, make sure the kit you select has one included. Since not all kits include a battery, you might find yourself browsing through options and landing on something at an unbelievable price. If that’s the case, double check it’s got the battery included. If not, then it is possible to source the battery yourself, but be sure about what you are getting.
How fast do electric bikes go?
This is hard to answer specifically as electric bikes are, on the whole, designed to assist pedalling rather than replace it, and it is the same with electric bike conversion kits. The measurement of the power of the motors is in wattage and, in effect, the higher the wattage of the motor, the faster speeds it will be capable of achieving.
However, the speed is often limited as a result of country-specific regulations. In the UK, the assistance an e-bike can legally provide is up to 25kmph (15.5mph) and, after that point, the bike can go faster but without any assistance from the motor. Anything faster would not meet the UK’s electrically assisted pedal cycles (EAPC) criteria, would be classed as a moped or motorcycle, and need to be licensed and taxed appropriately. The laws are different depending on the country, with the United States, for example, allowing more powerful motors – although individual states have their own legal frameworks.
Which bike is best for electric conversion?
You should consider the condition and componentry of your old bike. With an electric motor dramatically increasing the torque, using a low-quality or worn drivetrain will result in poor performance, with shifting being affected and the chain skipping or even snapping. Another important consideration is the brakes, adding the extra weight of an electric bike conversion kit and increasing potential speeds will put more stress on the brakes as they try to curtail momentum. We recommend choosing to convert a bike that has disc brakes as they will provide far better braking performance.
I haven’t heard of a lot of these brands, are they safe to use?
In the world of electric bikes, there are a lot of brands you may not have ever heard of. There’s been a boom going on for a while, so new brands are popping up all the time. Not only that but Europe, and especially the US, are playing catch up to the trend of electric bikes. You will probably stumble across a lot of unfamiliar brand names.
Consumers have a tendency to look away when they encounter a new brand. It’s not a bad strategy most of the time but in the electric bike world, including conversion kits, you’ve got to be more open than that. If you aren’t open to names you’ve never heard of you will find the options limited. A lot of the names you may come across are unfamiliar to you but have a solid history behind them.
That doesn’t mean you should go forward blindly. Do your research and be careful with your money, like always. The only thing that might be different is the need for being open to new companies. At the very least be willing to look a little deeper, read reviews, and do some research. The brand you’ve never heard of might actually be a well-established brand from a different part of the world.
Is converting my bike to an electric bike worth it?
There are plenty of reasons to install an electric bike conversion kit to your current bike, but the question of whether it’s worth doing is going to depend on your circumstances.
For many kits, once the installation has been completed, it will be an arduous task to remove it again, so one of the questions you’ll need to ask yourself is whether or not you want to retain the ability to use the bike as a ‘normal’ bike. If you expect to be flitting between the two (powered and non-powered) then a kit that can simply be folded out of the way – like the Rubbee X – might be perfect, but you might instead prefer to simply buy a second bike for the convenience.
The second question is to assess the state of your current bike. If you don’t yet have one, then the cost of buying a bike, buying an electric bike conversion kit and then fitting it, is probably not going to be worth the time, effort, or money involved. However, if you have a bike that is in reasonable repair, then the value for money – and effort – will be greater.
Beyond the financial and practical element, the question of ‘is it worth it’ will also depend on the amount of use you get out of it. E-bikes can be incredibly motivating and enjoyable and if converting your standard bike to electric helps you to ditch the car on a regular basis, then the answer becomes clear.
If you want a monetary answer to this question, then there are ways to work out whether the investment is worth it. Take a moment to think about your current car usage and work out the cost per day/mile, including fuel, parking and running costs. Try to work out how many journeys, days or miles you will use the bike for after it is converted. Once you know this, you should be able to work out the reduction in car running costs per mile/day and, with that, you should be able to work out how many miles/days it will take for the electric bike conversion kit to pay for itself.
Should I just buy an electric bike instead?
Remember to consider all your options. You have a bike in the shed you haven’t touched for many years and it seems like a perfect candidate for conversion to an electric bike. It might be, but it’s also just as possible that it’s a better candidate for a sale. Sometimes it’s better to take the money from that sale and put it towards an electric bike someone else built.
As with anything, consideration for the end-use during design and build can have advantages. A quality electric bike conversion kit might end up being very close to the price of a complete electric bike. If a company starts with a clean slate and designs an electric bike, it’s easier to keep costs low and integration high. Really consider why you are thinking about converting your bike and whether it makes sense compared to what’s on the market. In some cases, it will but in others, it won’t.
Are electric bike conversion kits legal?
The kits themselves are entirely legal, and fitting them to your bike is equally so. However, the question of legality arises in relation to where you then plan to use your newly powered electric bike. The answer will vary hugely, depending on where in the world you’re based, and which kit you choose.
For example, in the US, there are different classes of e-bikes that vary by their power, speed limitations and whether or not they have a throttle, and each class is subject to different rules. Things are a little more simple elsewhere, with the UK stating that anything with a speed limiter of over 25km/h is classified as a moped, while anything up to 25km/h (15.5mph) is classed as a bicycle.
Before you complete any purchase, make sure you have an understanding of the local laws that govern electric bikes, which is where our guide to e-bike classes comes in handy.
How do you install an e-bike conversion kit?
Sadly, there is no single and simple answer to this question. Each electric bike conversion kit works in a different way and therefore fits onto your bike in a different way too.
The most simple options are the friction-drive kits, such as the Rubbee X, which place a roller onto your rear tyre. In the example of the Rubbee, you simply need to mount the device onto your seat post, with the roller placed against the tyre. However, more complex systems require the removal of drivetrain components and wheels, and the installation of wiring. These are far from impossible, but they may require some tools and a bit of patience.
How much does an electric bike conversion kit cost?
will depend very much on the conversion kit in question. Some are available for as little as £250 (350), while the more high-spec and integrated kits can fetch as much as £750 (900).
Will a bike shop fit my electric bike conversion kit?
It’s understandable that you might not want to take on the arduous task of fitting your electric bike conversion kit yourself. You might not have the tools, the know-how, the confidence, or simply the time to invest. Luckily, almost all bike shops will be happy to fit it for you.
Some systems, such as the Pendix kit listed above, are only sold via physical stores and the fitting is sold as part of the overall package. However, with kits bought online such as the Bafang kit, the shop will charge you for the time it takes, which will add to the cost of the overall conversion. In our opinion, knowing that it’s been done correctly and safely is worth spending extra.
Some bike shops or workshops also may refuse to install a conversion kit to a bike they consider unfit for purpose or potentially unsafe. If you plan to have your local shop fit a kit it may be worth consulting with them on the job first to make sure they are happy to do it for you.
Individuals carrying out the instructions in this guide do so at their own risk and must exercise their independent judgement. There is a risk to safety if the operation described in the instructions is not carried out with the appropriate equipment, skill and diligence and therefore you may wish to consult a bike mechanic. Future Publishing Limited provides the information for this project in good faith and makes no representations as to its completeness or accuracy. To the fullest extent permitted by law, neither Future Publishing Limited, its suppliers or any of their employees, agents or subcontractors shall have any liability in connection with the use of this information, provided that nothing shall exclude or limit the liability of any party for personal injury or death caused by negligence or for anything else which cannot be excluded or limited by law.
How to convert a bike to electric power | Electric bike conversion kits explained
The best electric bike conversion kits will enable you to add a motor to your existing bike simply and relatively cheaply – at least compared to the price of buying a whole new electric bike.
There are an increasing number of ebike conversion kits out there, and they’re getting more sophisticated and easier to install on your bike, making for a practical alternative to a new purpose-built electric bike. An electric bike conversion kit will include the motor to drive you along and the battery to power it. It also needs to include the apparatus to control the power output level. This usually takes the form of a bar-mounted display.
In addition, a kit will include sensors to detect how fast you’re travelling and your level of pedal input to ensure the power supplied matches your needs. We’ve tested a few electric bike conversion kits here at BikeRadar, but there are lots more we’re yet to try. A full test of the best electric bike conversion kits is in the works – stay tuned. If you want a more detailed explanation of the different types of kit available and things to consider when purchasing an electric bike conversion kit, then head to our explainer further down the page.
Best electric bike conversion kits 2022: our picks
Swytch electric bike conversion kit
Swytch says its electric bike conversion kit can convert any bike into an electric bike. Stan Portus / Our Media

- Pros: Very compact; easy to install; variety of range options
- Cons: 100mm threaded front axle only; not compatible with thru-axles
London-based Swytch makes a conversion kit that, it says, is the lightest in the world at 3kg total weight. It can convert any bike into an ebike.
The kit includes a 40Nm brushless hub-based motor that comes pre-laced into a replacement front wheel. The lithium-ion battery pack connects to your handlebars and also acts as the system controller and LCD display.
There’s a crank-mounted cadence sensor, and that’s all you need to fit to your bike to get going.
There’s a Brompton-specific kit available too, with an adaptor for the Brompton’s front luggage mount.
Depending on the range you want, there are three sizes of battery pack available, which provide a claimed range of 35km, 50km or 100km.
Swytch has recently unveiled an even more compact kit with a.sized battery that weighs just 700g and, Swytch says, gives 15km of range.
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Cytronex electric bike conversion kit
Cytronex makes electric bike conversion kits for Bromptons, as well as standard bikes. Russell Burton / Immediate Media
- Pros: Clever sensor tech; decent range
- Cons: Not much onboard info on battery level and range
Weighing between 3.2kg and 3.6kg, the Cytronex ebike conversion kit is another front-wheel conversion to house a hub motor, but in this case, the battery is designed to fit in a standard bottle cage.
We tested the kit on a Cannondale Quick hybrid and reckon that conversion takes around 30 minutes. The charge level is displayed via LEDs on the battery, which also houses the system controller. We got up to an impressive 48 miles on a charge.
We’ve also tested the kit on a Brompton P Line lightweight folder, where the total weight undercut the C Line-based Brompton Electric. Fit it to a C Line and it’s also cheaper than the Brompton Electric.
Electric bike conversion kits: different types explained
Electric bike conversion kits come in styles to suit all types of bike. Russell Burton / Immediate Media
There are a number of ways to electrify your existing bike for assistance up those hills: you can fit a powered wheel, either front or rear; you can attach a drive unit to the bottom bracket; you can fit a motor above the rear wheel and drive it via friction; or, most sneakily, you can conceal a motor in the seatpost.
Whether you ride a hybrid, mountain bike, road bike or even a folder, tourer or gravel bike, it should be possible to convert your bike.
Many can even be fitted by a competent home mechanic if you’re feeling handy and have an afternoon spare.
So, what are your options? Let’s take a look at the different ways to convert your non-assisted bike into an electric bike.
Powered ebike wheels
The Swytch is a good example of a readily available universal electric bike conversion kit that uses a motor at the front hub. Swytch
Fitting a powered ebike wheel is probably the most practical option for many people.
A powered ebike wheel is built around a special hub that contains a motor. This is usually powered by a separate battery.
This sounds simple, but the main downside is that it adds rotating mass to your bike, which feels harder to accelerate than non-rotating mass.
There’s a steady stream of front- and rear-wheel conversion kits on Amazon and eBay, all looking suspiciously similar, priced from around £150 and with names you’ve probably never heard of.
Be wary of systems controlled by a throttle (also called ‘twist-and-go’) though. Legally, they’re classified as electric motorcycles rather than ebikes, and need to be taxed and insured. Take a look at our guide to ebike laws for more information.
Rear-mounted friction drive ebike conversion kit
Readers of a certain age may remember earlier incarnations of these in the 1980s/90s: a box that sits on your rear wheel and powers it via friction with a rubber flywheel driven by a motor.
The idea hasn’t gone away, and lives on in devices such as the Rubbee, which promises bolt-on electric assistance for nearly any bike.
Rubbee’s base model has a claimed weight of just 2.8kg, with a 16km range that can be extended up to 48km with the top-spec, 4kg version.
It works with any wheel diameter between 16in and 29in, has an integrated carrying handle and clips on and off your seatpost. start from €579.
Concealed ebike conversion kit
The Vivax Assist hid a motor in the seat tube of the frame and applied power directly to the axle of the crank. Vivax
Now we come to the low-key way to do it – hiding a motor inside your bike so no one knows it’s there.
The Vivax Assist was the best-known device for doing this, although the company has now ceased trading. It’s the system that was used by Belgian cyclocross pro Femke Van den Driessche in 2016 to power her way to victory in her home championships. She was found out at a subsequent race, got a six-year ban and quit racing.
Vivax Assist may be no more, but we reckon this idea still has legs – at least for the budding cyclocross cheat.
Mid-drive ebike conversion kit
eBay and Amazon are awash with mid-drive motor electric bike conversion kits like this one from TongSheng. TongSheng
Many commercially available ebikes are powered with motors mounted around the bottom bracket, near the pedals.
These have the advantage of placing the weight low down on the bike, making it more stable.
This isn’t just a ready-made option though – you can also buy aftermarket conversion kits with mid-drive units.
Bafang is a brand that is increasingly focusing on complete ebikes, but it also offers a mid-drive conversion kit on Amazon, as well as wheel hub motors.
Priced from £360, Bafang says the conversion is easy to install using only a few tools to remove the bottom bracket and fit the drive on the front of the down tube.
As above, be careful of throttle-controlled kits that won’t pass the UK ebike regulations and will legally be considered a moped.
You’ll find other mid-motor systems on Amazon too, such as that from TongSheng, which is claimed to fit 95 per cent of standard bike frames and be 30 per cent lighter than a Bafang unit.
It uses a torque sensor, so should fall within the ebike regulations, and is priced from around £350 – although that doesn’t include a battery.
German brand Pendix has a mid-drive system priced from €999 to €2,190 that weighs from 5.4kg for a 28km range. It replaces a BSA bottom bracket and can be fitted to folding bikes as well as a wide range of regular machines.
Folding ebike conversion kit
The Brompton electric conversion from Electric Concepts is one of many kits available to electrify an existing Brompton. Electric Concepts
What can you do if you’ve got a folding bike and want to join the electric revolution?
Well there’s good news if you’ve got a Brompton – a number of ebike conversion kits are available. They generally work with a powered hub in the front wheel and a battery carried in a bag mounted on the front.
As discussed above, Swytch and Cytronex can both be used to convert a Brompton. Swytch’s Brompton kit is priced at £999, although discounts of up to 50 per cent are sometimes available on the site.
As with its other systems, there’s a front wheel hub motor, a clip-on power pack and a bottom bracket torque sensor. Quoted range is up to 50km.
Swytch will also build wheels for folders with other wheel sizes and different fork blade widths, such as Dahon’s models.
Are electric bike conversion kits legal?
If your electric bike uses a throttle, it is technically classed as a moped, and must be taxed and insured as such. Simon Bromley / Our Media
Most electric bike conversion kits are legal to fit to a bike, although the precise rules differ depending on where you live.

In most of the world, the motor needs to be limited to a maximum of 250 watts of continuous power output, unless the electric bike is only used on private land.
You also need to be pedalling for the motor to work – a throttle can only operate at low speeds and assistance needs to cut out once the speed exceeds 25kph. There may be a minimum age to ride an electric bike: in the UK it’s 14.
The rules are different in the US, where higher power outputs and higher speeds are usually legal, while Australia has some variants as well, so it’s worth checking that your electric bike conversion kit is legal where you live before purchasing.
Is converting an electric bike worth it?
An electric bike conversion kit is not cheap, so you want to be sure it’s going to work for you.
You need to have a candidate bike in decent condition to justify taking the kit route.
If you’re going to have to buy a bike to fit the kit to, or going to need to make a lot of repairs to your bike to make it roadworthy, the total cost is probably going to mean it’s not a lot cheaper than buying a complete electric bike.
You need to be confident you can fit the kit yourself as well. If you’re going to have to pay a shop to fit the motor or sort things out if the conversion goes wrong, your savings over purchasing a new electric bike may dwindle quickly.
It’s also worth noting that an electric bike conversion kit may affect your bike’s handling, particularly if there’s a heavy motor and battery mounted somewhere where the bike was not designed to carry it.
Drivetrain components may not be adequately beefed up for the extra power they need to transmit and may wear or break. Factors such as torque steer may be a problem, and cabling and sensors can be unsightly.
In contrast, if you buy a complete electric bike from a reputable brand, it will have been engineered around the motor and battery, and you’ll know what the finished product looks like.
Can you convert any bike into an electric bike?
There are designs of electric bike conversion kit that will work with pretty much any type of bike. Kits are available that are engineered specifically for certain bikes, such as the folding bike conversion kits we’ve talked about above.
A design such as the Rubbee should be mountable on most bikes. However, tyre wear may be an issue with a road bike with narrower tyres, and wet-weather grip between the motor’s drive wheel and the tyre may also be a problem.
But some kits, such as those that work with a specific bottom bracket configuration, may not fit on some bikes. An unusual wheel size may also limit available options, so it’s worth checking the compatibility of your planned solution before buying.
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