Buyer's guide to electric bike kits

Everything you need to know about converting your bike into an e-bike

There's a wide array of electric bikes out there, with models to suit every pocket. But what if you're attached to your existing bike, whether that's due to its sentimental value or its financial value? An electric bike kit could help you convert your beloved ride into an ideal e-bike. Here Richard Peace, joint author of Electric Bicycles, looks at the pros and cons, compares some of the different models available, and offers buying advice.

Kits why or why not?

There are a number of benefits offered by kits over ready-to-ride electric bikes:

> A much loved bike can stay in use, with all the added advantages of a motor.

> A bike you've always fancied but which doesn't come in an electric version – even a folder or a recumbent – can be converted. This means you can get exactly the bike you want, with exactly the features you want. And when you want a change of bike, the kit can be swapped over.

> A kit can, with care, also be a way of saving money and upping quality compared to buying a pre-assembled electric bike. A bit of judicious shopping around for a good quality second-hand bike to convert with a decent budget conversion kit can give you a superior electric bike to a ready-made one at the same cost.

> If you're on any sort of quest for a lightweight electric bike, a kit can help with this, especially if you can afford to splash out.

Against that you need to consider whether you have the skills or inclination to fit a kit, or indeed whether you have enough technical interest to research the matter and make a choice. Bear in mind that not all kits will fit all bikes.

What to think about when buying an e-bike kit

Ease of installation varies from kits that are suitable for any DIY enthusiast through to those that should be handled by qualified fitters only – for example, the Gruber Assist. Electric bike servicing and repair isn't readily available at all bike shops, and this is especially true for kit conversions. For some work you may find it necessary to send your bike, or parts of it at least, to specialists.

Even though the majority of electric bikes are bought ready-made, there's a good range of conversion kits available and most can be fitted by a competent bike mechanic. The majority use hub motors and increasingly, these are offered ready spoked into a wheel. The budget systems tend to use a throttle control (E-bike), while more sophisticated models such as the BionX have pedal sensors so that the power kicks in only when you start pedalling (pedelec). Other systems offer a choice.

Always ask for a full list of requirements for any bike the kit is to be fitted to. For hub motor kits you'll need to check your frame's rear dropout width and what gearing the system is compatible with – you'll often find rear hub motors only work with screw-on type freewheels. With all types of kits, you'll need to find out the battery mounting requirements – eg. rear rack, frame or seatpost.

What different kits are available?

The most widely available kits include:

Alien / Suzhou Bafang: This throttle control kit comes as a front hub motor ready-spoked into a 26in (mountain bike) or 700c (road) wheel. Mounting points are required for a rear rack which carries the battery, and space is needed for a small bag or box to mount the controller and wiring loom, which needs a bit of care to fasten up securely. Cost: £600. Weight: 9kg.

BionX: This is a pedelec system with regenerative braking. It's good for touring or commuting in hilly country and is often used on recumbents and some folding bikes. The rear hub motor is ready-built into a 24in, 26in or 700c wheel. There are rack-mounted and frame-mounted battery options. Cost: £1,100-£1,800, depending on options. Weight: 5.5-8.9 kg.

Currie Electro Drive: This is a chain drive system which comes ready mounted to a 26in rear wheel (700c fitting possible with re-spoking). It's good on hills and for load carrying/towing. Cost: £400. Weight: 12.3kg.

Ezee: This hub motor kit is available with a good range of wheel sizes (20in, 26in, 28in, 700c – the latter three sizes coming with disc brake options. Cost: £895. Weight: 8kg+, depending on options.

Gruber Assist: This is probably the lightest system available at time of writing. It's designed for mountain bikers, or any reasonably fit cyclist, wanting a bit of assistance up the hills and is unsuited to stop/start town riding. A tiny motor in the seat tube drives the cranks, with the battery mounted in a saddlebag. Cost: £1,750 plus £100 fitting. Weight: 1.9kg.

Heinzmann: This is a superbly strong, high quality kit suitable for all uses. It's a throttle control system with pedal sensor option. The large hub motor will fit front or rear wheels. Cost: £1,155-£1,550. Weight: 7-9.3kg.

Tongxin: This kit is light and compact, and especially suitable for folding bikes (eg. the 'Nano-Brompton'). It's a throttle system with a small, powerful front wheel hub motor to suit most wheel sizes. Cost: £725, depending on options. Weight: 5.2kg.

Where can I get more detail?

Specialist kit fitters such as the UK's Electric Mountain Bikes, who sell Heinzmann, Gruber, BionX and Currie kits, will be able to give more detail on the particular kits they sell and whether they're suitable for home fitting or not.

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