Guide To E-Bike Conversion Kits | Electric Bike Report

Here’s a list of suggested e-bike conversion kits based on our knowledge of the firms involved. They have a track record of reliable service in the provision of electric assist kits.

Lightweight Hub Motor Kits – From around 7-9lbs / 3-4kg

Lightweight e-bike conversion kits are ideal for electrifying bikes when you also want the final weight of your converted bike to be as light as possible. This often applies to folding bikes that people will be lifting up regularly (or maybe a non-folding one they need to carry up steps regularly) but it could also apply if you just want a lightweight e-bike that’s quick and easy to ride once the motor has cut out at the legal assist limit.

Naturally these small kits don’t have the raw motor power of larger ones, though riders can prefer this as it gives them a more ‘bikelike’ ride and also probably means they get more exercise. So if you are quite a sporty rider and want a light e-bike that gives you just a bit of a helping hand up steep hills then a lightweight hub motor electric bike kit is definitely worth thinking about.

To keep weight low you are quite likely to get a small battery with such kits, so range may be at the low end of the spectrum – though some of these small kits are incredibly efficient, and if ridden by fairly fit riders can achieve very impressive figures indeed – for example tests on the Cytronex C1 have shown it to be on a par with some mid-drives with bigger batteries in terms of the range achieved.

Even better news, there are several companies producing small e-bike hub motor kits, mainly from the EU area where the 250W motor power, 15.5mph assist laws suit the smaller size more.

In this section we have classified e-bike hub motor kits weighing less than 4kg as lightweight.

The work of many years’ development in the UK, Cytronex uses a discreet geared front hub motor and a bottle unit containing batteries, controller and (more recently) Bluetooth functionality. There is little in Cytronex that is not manufactured in the UK, plus a plethora of original design features, including marine-grade stainless steel mounting mechanism for the bottle and a tiny sprocket movement sensor, responsible for delivering power.
At 3.2-3.6kg / circa 7-8lbs (depending on spec) it has to be one of the lightest retrofit options out there.

Though the battery is a modest size it keeps the weight down and the efficiency high, meaning an impressive range from such a relatively small battery. Cytronex currently have 5 patents and their own-designed tech includes the innovative sprocket motion sensor and their own unique design of bottle battery plus the unique new 2-way control, the “Boost Button”. There are EU and US spec kits.

2021 has seen quite a number of improvements that should see the Cytronex kit go from strength to strength. They are now using new lithium cells in the battery packs to give 198Wh, a welcome increase on the previous 180Wh, but still within the limit which allows the product to be transported on a plane. This is another unique Cytronex feature where the two battery packs inside the bottle are each 99Wh, just below the dangerous goods limit.

The new bottle battery units now have Bluetooth – Cytronex say ‘As our main PCB is inside the bottle with the battery, Bluetooth allows the users to monitor charging from their phones, for example. So if you charge up in a cafe whilst stopped for coffee or lunch, you can now see how much charge you have without going to check. Also you get the exact charge level on your phone and can alter the power levels on the go.’

The Boost Button is also new – there are 5 different colours now (for 5 power levels, instead of 3) and now you can move up and down through them by pressing on the left or right of the Boost Button. They have also further improved both the main C1 sensor (making it neater and easier to fit, and also making it universal – previously they had a slightly different mount for hub gear bikes). The Brompton sensor has also been further improved to make it even easier to fit.

Price range: From £1045 as of 2021, and their range of complete Cytronex-powered e-bikes includes most styles of bike including tandems and a Brompton-specific model we have reviewed here.

Swytch

The UK’s Swytch promise a kit to fit virtually any bike with the extra claim that it is one of the easiest kits out there to fit, with three main elements:

• 1. A front hub motor ready laced into 28″, 26″ and 16″ (Brompton) rims in stock and they also offer custom build service for other sizes. The only non-compatible wheels will be those with thru-axles which tend to appear on high end mountain bikes and so are much less likely to have such a kit fitted.
• 2. Battery options are 180Wh (‘Eco’ kit) and 252Wh (‘Pro’ kit) – both are relatively small capacity batteries as e-bikes go so if you think you can manage the extra weight of the larger pack on your handlebars that is probably the best option for most riders.
• 3. The universal pedal sensor (which has just gone through a redesign) can be easily configured to fit around the pedal crank on the opposite side to the chainwheel. It is essentially a circle of twelve magnets that communicate with a separate sensor fixed to the bike frame via a small sticky pad. Sensor and magnet wheel can be aligned using small Allen-head bolts so that they line up accurately – the idea being to get the magnets to pass as close to the sensor as possible without touching it.

I’ve tested the heavier 2.1kg (252Wh capacity) ‘Pro’ battery option and found that particular kit option added 4.45kg / 9.8lbs to the weight of the bike.

Vekkit

A relative newcomer, Polish firm Vekkit looks a very minimalist kit with a claimed install time of around 10 minutes. It comprises a front wheel with a motor, bag with a battery, wireless pedal sensor and wireless handlebar remote.

There are few independent reviews out there so all details are the company’s own; wheels size options from 16” to 29”, total weight added just over 3kg (smallest battery option) and battery option sizes are 180Wh, 187Wh and 360Wh. There are also options from folding bikes like Bromton and Dahon that have very narrow front forks.

From around €730 including shipping to the UK – that includes the smallest battery and no handlebar remote (app control only). They also appear to ship to the US but note the kits are UK/EU spec with 15.5mph assist limit.

Xofo are certainly not as well known as the likes of Bafang or Shengyi but they produce this neat little motor with a claimed 1.8kg weight that makes it a true lightweight. The Xofo kits on offer from Canada’s Grin are made specifically for the very narrow front forks on Brompton folding bikes. You can get battery complete systems starting at around US $1000.

Bafang G311

Bafang’s geared front hub motor version has a listed weight of 2.3kg and Grin has ‘ready to roll’ complete kit options or you can build your own system from individual components if you have that level of knowledge.
It is a step up in weight from the likes of Xofo and Cytronex but should offer a little more electrical assistance.

This small, light geared hub motor from the UK is great for Brompton conversions and similar where you want electric hill climbing ability but don’t want to add too much weight. Nano can also supply kits for Moultons, Dahons and other bikes on request.

The Nano system is based around a brushless 250w, 290rpm, 36v motor built into a Brompton front wheel which connects to a controller via a modified luggage block and luggage frame to enable the system to become live when the Brompton bag, containing the battery, is clicked into place. The Nano system for Bromptons is specifically designed to work so that the Brompton fold is unaffected. There are pedelec only options and pedelec plus throttle (but no twist and go option) as the kit is EU/UK spec with a max assisted speed of 15.5mph.

Recent developments include a slimmer motor which, on most Bromptons, will fit straight into the forks without any adjustment. If an adjustment is required Nano supply the necessary tool and instructions. The motor is under 2kg in weight with an excellent free wheel so you will hardly notice any difference when pedalling without using the motor.

Nano advertise the fact that their option of smaller 4Ah, 36V Bosch powertool batteries means they are one of the few systems that can be taken on a plane. Being Bosch, this option also means the batteries are readily available if you need replacements or spares.

Price range: From £800 for the kit alone for complete kits as of 2021.
Here is a review of the Nano system.

ARCC

From Cambridge in the UK, ARCC (like Nano) use an EU-spec front hub motor and Bosch powertool battery, but their approach is rather more high-tech, featuring a wireless ‘pod’ control unit. They specialise in kits for Brompton and Airnimal Joey folders as well as the classic UK Moulton design. The kit adds just under 4kg to the overall weight of the bike, including the battery. They also come ready fitted to ARCC’s own range of bikes.

The ARCC solid looking aluminium e2-pod is both a wiring nexus and battery mount clamped securely on to the head tube which communicates wirelessly with the handlebar-mounted Bluetooth controller (or an iPhone with appropriate app if preferred). Also feeding into the pod are the cables from a bottom bracket torque sensor and brake lever sensors.

Battery options are 144 or 216Wh Bosch power tool batteries and there is also the option of buying an even larger 324Wh Bosch power tool battery though that is not directly available from ARCC, despite this it’s easily available through DIY outlets and the like.

EBR has tested the Moulton option.

Price range: From £1799

Mid-weight Hub Motor Kits – Circa 9lb – 18lb / 4-8kg

Note that some firms mentioned in the Mid-weight Kits section, like Leeds, offer a fairly light option but this involves very small batteries and most of their offerings are over 4kg in weight. Also note some of the biggest batteried options from some of the brands mentioned are a couple of kg heavier than 6kg, but we have classed the brand as ‘Mid-weight’ as most of their kits are in the 4-6kg range.

A well respected Chinese manufacturer of (mainly) hub motors. GRIN produce ready to roll kits using their X1 and X2 motors.

As the motors themselves weigh around 6.5lbs / 3kg, most battery options should produce a kit in the 9-18lb / 4-8kg range

Dilinger US also produce a 17lb / 7.7kg kit that uses a 350W / 20mph Shengyi motor coupled with a 470Wh battery. There is also a UK/EU spec Dilinger kit with the same motor and battery. These kits are priced at US $699 / £699 respectively.

Leeds offers a nice range of affordable and easy to fit kits in 250 and 500 watt US spec options with a range of frame and rear rack mounting batteries. Mainly front hub motors but can do rear hubs on request. Disc-brake options. The option of a quick release fitting for the wheel nut is a nice touch too.

Price range: US $549-$1599 for complete kits as of 2021.

Here is a review of their 250 watt and 500 watt systems.

This video shows you the options available on their 250 series kit:

Hill Topper

Hilltopper is an economical front hub option that looks easy to fit. There are three options all based on geared front hub motors with the range topping Summit option being the most powerful with a 48V battery and 480Wh battery and weight of 21lbs / 9.5kg. The lightest option is the 16mph, throttle only , 36V, 194Wh batteries Sprinter option that adds 13lbs / 6kg. The middling Horizon option adds pedelec control to the Sprinter’s throttle only and a bigger 410Wh battery and comes in at 18lbs / 8kg and has a top assisted limit of 20mph.

Price range: US $549-$1099 for complete kits as of 2021.

Here’s an install video for the Sprinter option: