Electric bike conversion kits 2024: Add a motor to your bike

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. The battery voltage and output need to match the motor. It’s really important to make sure that your charger is compatible too;    charger incompatibility is cited as a cause of many fires caused by electric bikes.

It depends, and that’s why we’ve not quoted it for each kit listed above. Instead, we’ve included the battery size and motor power, to help you get a fair gauge of how one compares to the next. 

To help you understand why that’s relevant, a quick basic formula: A 100Wh (Watt-Hour) battery will last for one hour when the motor is putting out 100 watts of power. 

Different products come with different battery sizes and various motor powers, but as an example, if your e-bike conversion kit has a 250-watt motor, and it has a 500Wh battery, it will last for two hours at full power. 

To then convert that into a distance (to be able to quote a range) is even more confusing. Riding uphill will use more power but be slower than riding downhill, so you’ll cover different distances for the power output depending on where you live and the terrain you’ll cover. What’s more, one person may use full power sparingly, whereas another will use it everywhere.

And finally, if it’s cold, batteries perform worse than if it’s warm, so will drain more quickly in winter than in summer. 

With all that said, in our experience, a 200Wh battery paired with a 250w motor will get you around 25-30km when used on mixed terrain with a mixed use of power outputs. 

Some battery options will have much larger capacity than this though. Long-range electric bike conversion kits might give you around three times this range, although the battery will be larger and heavier and cost significantly more. 

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 25kph (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 same is true in the EU.

The laws are different depending on the country, with the United States, for example, allowing more powerful motors for some e-bike classes – although individual states have their own legal frameworks.   

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.

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 will be 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 to be 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. 

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 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. 

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 of 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.

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 and EU 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.  

The best legal electric bike conversion kit will vary by where you are based. In the UK and EU, a motor has to have a continuously rated power output of no more than 250 watts, whereas in the US a more powerful electric bike motor can be used. There are also higher speed limits for assistance in the US and an electric bike conversion kit can include throttle control, whereas elsewhere it needs to be pedal actuated.

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, and thus the fastest electric bike conversion kits to install, 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.

In general, a kit which includes a replacement wheel is likely to be faster to install than one that sits in your bottom bracket, as removing your old wheel and fitting a new one is relatively straightforward. It’s then a question of bolting the battery to your frame and cabling the two up, along with any extra control units and sensors included in the kit.

Prices 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) or more. 

An e-bike conversion kit will add significantly to the value of your bike and, if it’s easy to install, it’s also easy to remove. It’s worth considering insuring your e-bike conversion kit, just in case.

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 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. 

Like all of our buying guides, our advice is gained through countless hours of using products in the real world, often back to back against their peers to compare them, but ebike conversion kits have an additional need. 

If a conversion kit is too tough to install, it will cost you more as you seek the help of a professional. Therefore, with our testing, we also spend time fitting the kit to the bike in the first place, judging how long it takes and how intuitive it is. 

Once that’s done, we do the real-world testing, judging the range, the ease of use and the durability of the product in question.