Which is the best electric bike conversion kit for my bike?

The post Which is the best electric bike conversion kit for my bike? appeared first on Cycling Electric. Following very swiftly on from our guide to the which electric bike motor is best for your needs, we’re now taking a deep dive on which are the best electric bike conversion kit options for your bicycle. This one is, unfortunately, a thorny topic. Great care and attention is advised when shopping; there is no […] The post Which is the best electric bike conversion kit for my bike? appeared first on Cycling Electric.

Dec 8, 2023 - 16:39

The post Which is the best electric bike conversion kit for my bike? appeared first on Cycling Electric.

Following very swiftly on from our guide to the which electric bike motor is best for your needs, we’re now taking a deep dive on which are the best electric bike conversion kit options for your bicycle.

This one is, unfortunately, a thorny topic. Great care and attention is advised when shopping; there is no one ‘best’ electric bike conversion kit solution. In many cases, it’ll be dependent on the type of bicycle you have in mind for the conversion. If you think that buying an e-bike outright might be better, then we have a buyer’s guide for the best e-bikes under £1,000 and the best e-bikes under £2,000.

Electric bike conversion kits – need to knows

In many cases, adding such a kit will invalidate a bike’s original warranty and at worst you could inadvertently end up with something illegal. We’ll explain all of that in more detail, but don’t let these things put you off. It may be that a conversion kit could give an unloved bike a new lease of life. Pedal-assisted cycling has been shown to encourage people to ride more often and for longer per trip, very often replacing expensive car or train journeys; so all-in-all, such a kit could be a huge money-saver.

As with anything mechanical and more so because this is also a delicate electrical product, we strongly advise that even if you do buy such a kit that you have a professional fit it. In fact, why not consult your local bike shop before you buy? They have the expert knowledge and will be able to point out any compatibility issues ahead of your purchase. We are strong advocates of the local bike shop‘s knowledge, so give them a call or visit to hear their thoughts. They may even have a product in house that could serve your needs better.

Why is this worth the investment of your time, you ask? The reasons are both mechanical and electrical. To summarise, a bicycle manufacturer won’t have accounted for this kind of modification of its standard product and more so, won’t have tested its manufactured product to account for the additional stresses adding a motor can place on components. This is why they cannot guarantee a warranty against a modification to their products; there is simply no way to make such a grand speculation.

While electric bikes can only go roughly about as fast assisted as a fit cyclist can unassisted (25kmh/15.5mph is the legal assistance limit in much of Europe), the average speeds are likely to be higher, as is the weight of the cycle. The physics of additional speed and mass equate to the need for better engineering, something that is obviously not directly accounted for by either the bike maker, nor the electric bike conversion kit label; ultimately that means there is no ‘best’ one-size-fits-all solution.

The best electric bike conversion kit is a legal one

We hear you, you may wish to go a bit faster, but the law is equally clear on modifications as it is on standard issue electric bikes. To recap, that law is:

An assisted limit of 25kmh (15.5mph)
A maximum power output of 250W
Able to be ridden on roads and cycle paths
Does not need a licence, tax, nor insurance
Is essentially a bicycle in its legal standing
Is based on a pedal-assist system. Throttles are not permitted unless the e-bike is type approved.

That final point is particularly relevant in your Googling as many of the kits that will make your bike illegal to ride anywhere other than private land do tend to offer a throttle. Other tell-tale signs can often be indicated by the power output offering more than 250W, sometimes substantially more. It’s these kits that will see you converting your bicycle into what is, legally speaking, a motorcycle. As a result motorcycle laws then apply to you, the rider. You can therefore get points on your licence if found riding one without the proper registrations, insurances, taxes and even if you are not wearing a suitable helmet. You also would lose the right to ride on cycle paths, as is permitted to legal electric bikes.

It is worth addressing an elephant in the room. You may have read that electric bike conversion has resulted in a spate of fires; some clarity is needed on that point as it’s complicated. To explain in full, we have a handful of dedicated articles on the subject of what may be causing these issues, but for the most part, as long as you’re buying a legal kit and fitting it properly, you’ll be just fine – even specialist insurers agree, despite having the opportunity to gain from hysteria.

Finally, note that no two kits are quite the same and styles vary. A conventional approach is to replace a wheel with one that carries a hub motor and place the battery in a bottle cage, but of course that loses you a bottle cage mount. Alternatively, there are mid-drive kits, like the Bafang unit featured later, which place the weight nice and low, but may affect your clearance. Each system has pros and cons and it’s for you to assess which best suits your bike’s frame, accounting for its shape and strength.

Which is the best electric bike conversion kit for me?

Swytch electric bike conversion kit

Swytch e-bike conversion kit best electric bike conversion kit article

From £625 | VIEW OFFER

We reviewed the Swytch electric bike conversion kit back in May and warmed very quickly to its simplicity. It comes in two versions – the £649, 709g Air and £849, 1,076g Max – which as the names suggest provide differing ranges based on the battery capacity offered. Overall, we weighed the systems as weigh something like 2.84kg or 3.13kg, in total.

The brand claims that its kit will fit 99% of bikes out there and, judging by its compact size and integration of the motor into a wheel, it’s hard to argue any different. In fact you’re not limited by wheel size or brake type.

The key thing you’ll be looking at aside from the price is the claimed range for each battery. Swytch have that as 15km assisted for the 90Wh Air and 30km for the 180Wh Max. The motor has a 40Nm torque.

What is important to remember when considering these numbers is that they are not guarantees, rather fair use averages. If you’re a heavier rider the motor has to do more work; if you’re riding in the hill a lot the motor has to do more work; if you’re riding off road on uneven terrain the motor has to do more work; if you’re on assistance mode 5 of 5, the motor has to do more work. You get the idea and of course this trail of thought applies to all e-bike systems.

The Swytch system can charge from as little as 1.5 hours thanks to a newly-available 3A charger that’s compatible with the Max battery, though otherwise it’ll fall somewhere between one hour and 2.5 hours.

Pros
Unobtrusive, light and presentable
Hub integrates into the wheel
Weight is reasonable
Easy to fit

Cons
In a purely cost to capability ratio, you may decide just to buy a cheap e-bike for similar all-inclusive specs

Boost conversion kit

From £522 | VIEW OFFER

British tinkerers of electrics, Boost, has been in the market for electric bike conversion kits for a while now, but before that also produced cycles that would more likely be found on our sister website, cyclist.co.uk.

That means that the engineers with the team have a background in design that straddles both borders and as such understand a little about optimising the process of converting a bicycle. As such there’s a system built for more or less any bicycle and also specialist projects in the pipeline targeted at popular platforms like Brompton’s folding bike.

The business is incredibly reactive to a changing marketplace, with the founder also keeping close tabs on the ongoing VanMoof saga, pitching the idea of replacing electrics for owners, should the electric bike company have no future. In short, this is an agile business, with a 3D printer, a lot of ideas and a successful kit already on the market that’s even seeded in some bike shops.

The main system on the market at present is able to convert most bikes, has a bottle cage ready battery that claims to assist to approximately 50km and pairs to a rear wheel motor.

The kit can be bought for DIY assembly, but the brand prefers to route customers via bike shops in order that the correct configuration of replacement wheel is specced. The system carries a one year warranty and has a free to download app that governs some of the assistance features.

If you do feel happy fitting at home, all you need do is tell the brand your bike’s wheel size and they’ll build their hub into a custom wheel upon request with a 7 to 11-speed cassette to match your bike. Your bike must have bottle cage mounts to fit the battery.

Pros
Suitable for bikes with 26″, 27.5″, 28″, 29″ and 700c wheels
The all in price, installed in a shop is £695, which feels competitive

Cons
Doesn’t automatically come with a display, but can be bought, if desired
Not compatible with through axle yet (QR, 9.5/10mm solid axle only)

Skarper

From £1,295 | VIEW OFFER

This one’s not officially ready to go as yet, but it does have some big name backing in that Chris Hoy is an ambassador.

The Skarper DiskDrive system might represented the best electric bike conversion kit for the placement of the weight in that the clip on system has a super low centre of gravity thanks to its below chainstay placement. What you do need, however, is a bike with disc brake capability as the Skarper system relies on generating its propulsion by utilising a custom rotor as a point of contact.

This, apparently, has no impact on braking and is advertised as being a safe way to propel your converted bike. We haven’t tried one as it’s not launched yet, but we’re curious about the unconventional approach.

The Skarper conversion kit is an all-in-one package that integrates both the battery and the motor into the casing. It is apparently capable of 50Nm of torque, weighs 3kg, plus an extra 300 grams for the DiskDrive rotor and offers an ‘up to 60km range’.

Pros
Apparently easy to fit
Visually better than most
Comes in a 20kmh version for the US market

Cons
Unconventional idea that places a lot of trust in one unbolstered area of the bike

Bafang mid motor kit

£510.70 | VIEW OFFER

Mid motor systems are generally preferred by e-bike makers as they’re able to deliver a higher torque and place the system weight in a desirable area to maintain a bike’s balance.

The Bafang mid motor replaces your bottom bracket axle, sliding the motor’s axle through the shell in order to offer up a pedal assist system. The catch, because this is adding a weight directly to an area of the frame where there’s lots of welding, is that the bike it’s fitted to must be alloy and with a bottom bracket width of between 68 and 73mm.

One thing we will advise, from our shopping around, is that you should seek out the 250W system to remain inline with UK regulations. More powerful options exist online and these will see you fall foul of road laws without accounting for the fact you are essentially creating a motorcycle.

This system will very likely require specialist knowledge and tools to fit, so be sure that your local bike shop is happy to fit the product before you take it in. Most bike shops will not, for liability reasons, touch the more than 250W motor kits.

With an 80Nm torque, this conversion kit is likely the most capable for steep terrain. Be aware a battery is sold separately.

Pros
The weight is in an ideal place
High torque
No need to switch out wheels

Cons
Be sure to buy the right version for UK regulations

Cytronex C1 conversion kit

From £982.99 | VIEW OFFER

The Cytronex kit tips the scales at around 3.6kg and will cost around £950 all in, albeit there are several levels of customisation that will, for example, let you choose between a Mavic or a Halo rim. There’s also a fast charge option which may add appeal, though that adds £128 to the bill, plus it appears the shop sells compatible e-bike lights that can be wired with the system.

The C1 conversion kit comes with a battery of 180Wh, which weighs 1.5kg. The motor, meanwhile, can be specced for either EU or US regulations and adds a further 2kg. The battery is mounted via your bottle cages and the hub motor is built into a wheel, with a sensor tracking your cadence via the cassette.

Cytronex’s website can somewhat simplify the process for you, in that it actually offers bike sales that come equipped with the kit, so you can buy everything at once in confidence it is well-fitted.

The motor system carries a one year warranty and a separate manufacturer’s warranty applies when bought as a bike package. Batteries in Cytronex products purchased on or after 18th July 2020 are covered by a 2 year warranty.

The C1 comes with a partner app that will enable you to fine tune the assistance each mode offers. These power modes are indicated by a handlebar mounted ring that changes colour based on your output.

Pros
Fast charger option gives 90 minute charge
Shop sells custom options, including lighting
Possible to test ride at a UK bike shop

Cons
Expensive in context of buying a new e-bike, or even a quality second-hand

Rubbee

From €579 | VIEW OFFER

The Rubbee burst on to the scene with a new take on a somewhat old idea from the DIY e-bike conversion world where people used to rig up drill motors against rear wheels to get a bike moving. This, is of course, far more sophisticated, safer and legal. What’s more, it’s likely the easiest system to fit at home.

As you’ll see in the picture, in this instance the entire system is mounted to the bike’s seatpost (which somewhat rules out bikes with dropper posts) and touches down on the tyre. Friction from a whirring motor at the rear propels the rider, with rollers touched down on the rear tyre. For that reason, we suspect this system will work best (quietest, anyway) on urban tyres versus knobbly off road tyres. That said, we have, as yet, not personally tried a Rubbee, so cannot say which bike type best suits this electric bike conversion kit.

There’s some interesting features here, despite the unconventional approach, including a rear light that indicates the rider slowing down. Everything is of course all built into one package too, which simplifies things and means no wheel changes. It also boasts some regenerative braking, which recharges the battery incrementally.

That said, the weight of the unit is placed high up, which is not generally conducive to improved bike handling and we do wonder what happens with all the road muck and grime. The system, obviously, does not work if your bike has mudguards, so it’s probably a warm climate option.

The basic system weighs 2.8kgs, while a larger battery capable of around 20 miles assisted rather than 10 weighs 3.4kg.

The system is priced from €579 with €99 add ons for upped battery specs.

Pros
Regenerative braking adds battery life
Trio of options for range (though one is US-specific)
Easy installation
Builds in a rear light that indicates rider speed

Cons
Maximum tyre width compatibility is 2.5″, ruling out fat tyred bikes
Won’t work with mudguards or a pannier rack

Which is the best electric bike conversion kit: Frequently asked questions

What is an electric bike conversion kit?
If you have a bicycle that you are not riding as much anymore, but think you’d like to get back into cycling without wasting the asset you have, one of the best ways to get moving again is to add an electric bike conversion kit.

With one of these kits fitted you will have a motor that senses your own pedal power and offers you some matched energy in return, helping you get back to fitness, take on the hills and enjoy riding again. As with any electric bike these kits can help you get exercise if you are carrying an injury, or simply feel unable to cycle on your own steam for any reason.

How do I know if my bike is compatible?
This information will be found on the manufacturer’s website, but each of the motors we have featured here have a high level of compatibility with bikes of all shapes and sizes.

Consider when buying your bike’s frame and the available space for kit, plus whether the bike is in good enough shape to accommodate additional weight. If there are any signs of stress on the frame have them checked out by your local bike shop and ask specifically whether the bike will cope with additional forces and weight.

Are they dangerous?
If fitted correctly and aligned to the UK/EU regulations then no, these kits can be a very sensible and somewhat eco-friendly option to reviving an old bike.

We do, however, strongly recommend against tampering with electrics or batteries yourself as legitimate products undergo stringent testing to ensure safety. DIY solutions are those that are most commonly found to cause fires. Think of it like this – would you modify your toaster without knowing what you’re doing? No. An e-bike is much the same, it’s electrical and there’s a big battery that can be dangerous to play with without professional knowledge. Everything should be watertight and all charging equipment appropriately matched. DIY tinkering is therefore not advised.

How much should I spend?
One thing to factor in when buying is that it’s best practice to also upgrade your brakes to account for the added forces put through a bike fitted with an an electric bike conversion kit. Factor that into your bill, as you cannot put a price on safety.

It is also worth considering, if your budget is limited, whether the cost of a kit is a majority of the way toward buying a cheap electric bike. As with all things in life, you can get what you pay for, so check out our other buyer’s guides for advice.