E-bike conversion kits are an often overlooked option. If you have a bike ready to fit one, they can certainly be an economical choice - but it's not all about saving money as the best e-bike conversion kits can also pack a punch in performance terms. These options may be pricier, but they can give you something that measures up against the best electric bikes for lower overall cost.
There might be other compelling reasons to think about retrofitting. Your old bike might fit you like a glove or you might just be sentimentally attached to it but feel an electric boost will get you out and about on it more. If you have a relatively unusual bike like a recumbent or a trike 'off-the-peg' electric options to replace it may be limited and kit options could be a good way to go.
For more general info on e-bikes check out our beginner's guide to electric bikes, as many of the basic points made here apply to kits too.
Best e-bike conversion kits 2023
- Cytronex (Best overall) | Buy for £1,045 from Cytronex
- Swytch (Best lightweight kit) | Buy from £449 from Swytch
- LaVita Boost (Best for 'bike-like' feel) | Buy from LaVita from £549
- Dillenger Samsung Power 2.0 (Best value) | Buy from Dillenger for £599
- Nano for Bromptons (Best for Bromptons) | Buy for £820 from Nano
- Bafang BBS01 (Best for hill climbing) | Buy for £799 from Dillenger
- Revos eBike Kit with 200Wh battery (Best friction drive) | Buy for £599 from Revolution Works
- Zehus (Best high-tech kit) | Buy for £1,290 from Nfixed
- Heinzmann (Best quality motor) | Buy from £1,581 from EV Solutions
- Pendix (Best for hard to fit bikes) | Buy for £1,590
- ARCC (Best overall quality) | Buy for £1,799 from ARCC
The higher price of the Cytronex kit reflects the fact that it is designed from the ground up to produce a lightweight and high tech solution that will feel extremely bike-like to ride and which will offer ground-breaking range from the 198Wh battery. Our tests on earlier versions of the kit (here and here) show the British company has largely succeeded.
The Cytronex battery is designed with two independent battery packs inside which means that the original 180Wh battery (as reviewed by us, now updated to 198Wh) can be transported by air because it is classed as two batteries of up to 100Wh installed in equipment. Other products that have followed suit recently only provide one battery, consequently the capacity is less than half that of Cytronex, and the Cytronex battery goes a long way for its size. A new Mini Charger that will fit in a standard bicycle seat pack, has now been introduced, and provides an 80% charge in about 2 hours.
The front hub motor may look conventional enough but a plethora of original design features include a quick release bottle battery, a simple but highly functional handlebar mounted ‘Boost Button’ and a sprocket movement sensor mounted out of the way on the chainstay. The Boost Button has been improved since our review – now offering 5 power levels which can be changed by pressing left or right. The unique patented Cytronex sensor senses the sprocket gear teeth which means that no brake switches or speed sensors are required. The sensor has a new neat and compact chainstay fixing for 2023.
Along with the ARCC and Pendix systems this is probably the highest quality system featured and includes impressive details such as a marine-grade stainless steel mounting mechanism and Bluetooth functionality that, via the brand new smartphone /tablet app, lets you not only alter the power of the five motor assistance levels but also monitor the exact charge of the battery even when it is off the bike. This means you can also monitor charging - a very useful feature at a coffee or lunch stop. Diagnostics in the smartphone App allow Cytronex to diagnose an issue from a log sent anywhere in the world.
At 3.2-3.6kg depending on spec it is also one of the lightest retrofit options out there.
In addition to the kit, Cytronex offer complete bikes from the likes of Cannondale, Whyte and GT. There is also a Brompton specific option and a tandem option.
UK-based Swytch are known fro the small and sprightly front hub motor allied with a pedal sensor that fits around the pedal crank and a handlebar mounted battery. Its remarkable success has been due to a combination of an attractive price (the most heavily discounted price meaning you have to wait a few months to get a 'bulk discount' rate) and a claim of almost 'universal' fitting (it's certainly one of easiest and most widely compatible kits available).
New for 2022 is the battery itself and the battery mounting system, all designed to make the system lighter and more manageable. There are two battery options (98Wh and 198Wh) and the smaller one, the Air, is reduced in size by 70% and weight by 50% compared to its predecessor. The Air which has a claimed weight of 700g and measures little more than 20x10x2.5cm - ideal for a large pocket or a small bag. There is also a Max version of the battery which is only 1.4cm longer but twice as thick.
We found even the lower power levels provide a very useful amount of power so that 10 miles is a reasonable mileage estimate from the small battery if the power is used a little sparingly. We were also impressed with the optional display that lets you easily change power levels or switch the power off (the Swytch is a nice system to ride with no power too).
Read the full Swytch e-bike conversion kit review.
Launched in 2022, the LaVita Boost rear wheel hub motor system is both one of the easiest to fit kits out there and one that gives the most 'bike-like' ride. It does that by integrating the sensor into the rear wheel, using a wireless handlebar display and by keeping the kit's weight in the optimal position on the bike so that it doesn't affect handling. There is just a single wire run from the fame mounted 'bottle battery' to the rear hub motor.
The downside is it's relatively limited compatibility when it comes to donor bikes. At the time of writing it was limited to 700c and 26" size wheels with derailleur gears (ie it's not compatible with hub geared bikes). The semi-automatic power delivery was generally smooth and effective though the want of a bit more power up steeper hills was our only real criticism.
We concluded 'In short, the Boost is a uniquely simple offering, ideal for both leisure and sport riders who want a bit of assistance whilst keeping their bike light and with riding characteristics as little affected as possible by the addition of the kit.'
The internet is awash with cheap hub motor kits from sellers you are unlikely to have heard of, but Australian-based Dillenger sell in a number of countries and have done so over a number of years, building up a good track record in the process. Their website also offers good info on compatibility and fitting and they offer a clearly set out one year warranty.
Dillenger’s Samsung Power 2.0 front hub motor kit packs a lot of value in given the budget price so it’s perhaps not surprising they claim to have sold over 10,000 worldwide.
It ticks all the boxes: it’s disc brake compatible (standard 6 bolt mounting), comes ready spoked into a wide range of wheel sizes (20”, 24”, 26”, 27.5” and 29”), has a decent sized 468Wh battery (with USB socket for charging devices) with cells from a recognised maker (Samsung) and also has the option of a throttle.
Bromptons have narrower front forks than most bikes and Nano’s Brompton-specific kit is based around a brushless, front hub 36v, 250w, 290rpm motor with a weight of 1.6kg. This comes already built into a new Brompton 28-hole double-walled rim. Nano have long experience of providing e-kits for Bromptons and the latest iteration of their popular kit adds around 3.3kg total to the weight of the recipient Brompton. It features a single 144Wh clever and practical ‘in bag’ battery. Larger batteries are available.
With Brompton’s own electric version (not retrofittable) starting at almost £3,000, and weighing in at 17.4kg, the Nano option fitted to a second hand titanium-specced Brompton (typically around £1,500) looks a very tempting option.
Undoubtedly the most popular mid-drive kit in the western world - where mid-drive kits are rare indeed. The BBSO1 is rated at the UK/Euro motor output level of 250W whilst the BBSO2 is rated for the US market at 750W. The Dillenger version comes with a 522Wh battery so the sub-£1,000 price tag looks attractive. Like Dillenger’s front hub motor kit, the battery has a 5v USB socket handy for recharging.
You need to be happy removing and reinstalling components in the bottom bracket area of the bike of course, but if you are, you should get all the benefits of a much more expensive mid-drive e-bike (currently most mid-drives cost well over £2,000).
The kit weight is stated as 7kg, which is pretty heavy for a kit, but the weight is nice and low down and produces a well handling bike that’s also easier to pick up than you might think. The motor position also means your front and rear wheel setup can remain just as it is.
Instead of using a motor in the wheel, the Revos system is based on a friction drive unit. The motor is in contact with the rear tyre and directly drives the tyre when you’re pedalling. This is powered by a bottle-cage-mounted battery, and there’s a cadence sensor which you fit to the crank. That’s pretty much it. The version we tested with a 200Wh battery weighed in at just 2.7kg.
If you’ve got a bike you like and you’re looking for a way to simply give it a bit of power to help you along then the Revos is about as simple to fit as a system could be. You shouldn’t expect huge power or range from it, but the assistance is meaningful and welcome.
Take a look at our review of the Revos Kit With 200Wh Battery.
‘All in one’ kits – with all the elements required to add electric assist to a bike in a single wheel hub – were a growth area a decade or so ago, with new designs regularly coming along. However, many have faded from view.
The Zehus system appears to be going strong though. It is a gearless rear hub system that can be purchased both as a retrofit kit and on certain ‘off the shelf’ e-bikes - we have tried it on both the incredible Hummingbird Electric and the latest much improved version is fitted to the impressive Vello+.
So far models available in the UK have all been single-speed models but the Zehus website suggests versions that can take 4, 7 or 9 derailleur gears also exist. Stated battery capacity is 173Wh which is 20% bigger than its predecessor and Zehus Gen2 also claims 50% more torque. To quote our Vello+ review, there is 'a much more reliable Bluetooth connection to the handy Bitride app.'
Zehus Gen2 retains high tech features such as the regenerative braking and a built-in inclinometer to measure gradient.
The Zehus has a stated weight of around 3.5kg and various wheel size options are available from Nfixed in the UK. You may also see the system branded as the Flykly Smartwheel.
This longstanding German manufacturer produces electric drives for everything from tracked snow vehicles to electric boats, so e-bike motor technology should pose few problems for them.
The only motor kit currently available in the UK (via exclusive supplier EV Solutions) is the DirectPower gearless motor. This is a quiet and very high quality motor with a good amount of power but at 4.5kg for the front wheel version, this is certainly going to be one of the heavier kits out there. This is motor weight only too – the standard 500Wh battery will add several more kilograms. But if solid construction and high reliability (and the possibility of regenerative braking) are high on your list, and you don’t baulk at the very high price, this certainly could be an option.
This German-designed high quality kit places a gearless motor in the non-drive side of the cranks. It’s a very pricey but very high quality system. There are three options of increasing battery capacity, starting at 300Wh.
It is a very neat, minimalist looking system that requires minimal cabling. Control is via a knob on top of the cleverly designed 48V battery. It’s pretty heavy - the lightest version adds around 8kg. There are folding bike versions as well as options for regular bikes.
Pendix don’t give out detailed fitting instructions as they insist their kit is fitted at a dealer. It is distributed in the UK by Velobrands and there is a dealer page on their website.
ARCC, like Cytronex, produce a small, lightweight and high tech kit based around a geared front hub motor. Like Cytronex, they actually UK manufacture many of the components they have designed themselves.
They use small capacity Bosch powertool batteries which are mounted in the ‘Intelligent Drive Unit’ that is permanently fixed to the head tube, minimising the cable run to the front wheel motor (though it does all make the bike rather front heavy). An extra battery can be frame mounted using ARCC’s own bespoke battery holder. Perhaps the most impressive element of the kit is the wireless handlebar unit used to control power settings.
There are Brompton specific options, disc and rim brake options and the system comes with a five year warranty on the ARCC system and a one year warranty on the batteries.
ARCC do not allow ‘home fitting’ and you need to send or take the recipient bike to ARCC in Cambridge. If you want a complete bike then ARCC sell a small range of these too, including Moultons and their own-manufactured Abington and Rosemont town bikes. Ebiketips has already reviewed their electric version of the Abington.
The kit itself adds just under 4kg to the overall weight of the bike, including a 144Wh battery (216Wh batteries are also available from ARCC and 324Wh ones from third party sellers).
ARCC say early 2022 should see the launch of a new app (on both iOS and Android) and a new version of the handlebar control unit with a screen and more ride data.
How to choose from the best e-bike conversion kits
Will it fit my bike?
Hub motors not only need the correct width dropouts but also the profile of the forks in the area of the hub motor should not foul its smooth running. The better kit providers have motor templates or measurements, so you can check before purchase if the kit will fit. Will the battery fit where it is supposed to? Sometimes things can be modified to fit - e.g. fork dropouts or motor axle filed down slightly to ensure fitting - but some kits just won’t fit to some designs of bike.
Mid-drive kits are more widely compatible but require a higher level of bike maintenance skills. We fitted one so you can see just what is involved here.
A good kit provider should have a list of relevant questions that will allow you to tell whether the kit they are selling will fit your bike. If they unable to say whether the kit will fit or not it may be best to look elsewhere.
How complicated and time consuming is it to fit?
All kit fitting requires at least basic bike DIY skills such as swapping out a wheel and refitting a tyre. At the more complicated end are mid-drive kits that require you to remove the bottom bracket, perhaps to fit a torque-sensing bottom bracket or even a mid-drive motor.
Check how many separate, interconnected wired elements there are. Some of the budget-priced kits may come with brake cut-out levers (though often it isn’t necessary to fit them) and both cadence and speed sensors (simpler kits feature cadence or movement sensors only). You also need to ensure the cable runs between components will reach to where they are supposed to, so again if this info is not available, check how many cables there are and what their lengths are.
Simply put, the more interconnected elements there are, the fiddlier the kit will be to fit, the more potential problems there will be and the less ‘clean’ the converted bike will look. The LaVita Boost is the simplest kit to fit we have tried.
Note that a minority of e-bike kit producers (eg ARCC and Pendix) will only allow their kits to be fitted by themselves or accredited bike shops.
Can e-bike conversion kits be removed?
Kits can of course be removed to give you your old bike back - you might even want to try out another kit. They can be swapped between bikes too, adding further versatility. Most kits need at least some basic DIY skills, whilst some require more advanced ability but generally never anything too daunting. The summaries above highlight the skill required and the reviews will provide further detail on what may be involved.
How much weight will it add?
Conversion kits can be a surprisingly effective way to own a lightweight e-bike. They range from around 3.2kg (eg Cytronex, Swytch and Nano) all the way up to 9kg or more for a very beefy motor with an extra large battery. This means that if you're looking for the most economic way to get a bike with power assistance, a high quality e-bike weighing 10-12kg may now be within your financial reach.
Is there a 'best' design of kit?
Not really - it all depends what's important to you. Mid-drives are generally more powerful but add more weight. Rear hub motors give a better balanced bike than front hub motors but will fit a smaller range of donor bikes. Bigger batteries add more weight but also more range.
Are all kits legal?
No - be careful as it's an area rife for selling kits that don't comply with the UK regs. Beware in particular kits described as 'high performance' or 'off-road only'. As with legal 'off-the-peg' e-bikes, conversion kits should be limited to 15.5mph assist with a 250W rated motor and no 'twist and go' throttles are allowed. If the kit is described as complying with EN15194 it should be legal.
For more on e-bike conversion kits, keep an eye on our reviews section.