How to fit an electric bike conversion kit - what you need to know | Boost Bikes

Assuming you're clear on the benefits of a rear-wheel electric bike kit (see our guide to why they are better than mid or front-wheel drives), here's how to go about upgrading your bike. Our installation guide has step by step instructions - this guide will help you:

In general, you can fit the kit yourself if you’re happy replacing tyres and adjusting gears and brakes. If you’re not - for instance your bike maintenance is limited to repairing punctures - you should use a shop to fit it.

The warranty process is the same whether you or a shop fits it. We don’t anticipate problems, but if you have any, post the kit back to us and we’ll deal with the issue.

What’s in the kit?

Electric bike conversion kits consist of three main parts;

  • A new wheel with a hub that contains the motor and sensors
  • the controller (the brain of the system and the power control] which holds
  • the battery

To fit the kit you need to replace your existing wheel with the new one and connect the hub wire to the controller which you fix to the frame. That’s it!

Fitting the kit yourself

Most people go for the £649 kit, where we custom build a wheel to match your bike, which takes two to four weeks to come. (If you’re an advanced mechanic, you can opt for the £522 version where we supply the motor but you have to [source your own rim and spokes and ] build your own wheel.)

Once we’ve sent you the new wheel, it should take about 20 minutes to fit. The wheel can be supplied with a new cassette fitted if you want (the cassette is the set of sprockets the chain moves through as you change gear).

The only tool you’ll need is an adjustable spanner or a ring spanner that fits the nuts on your bike’s axle.

The wheel

The wheel is custom built for you - when you order it, you’ll be asked your wheel size:

  • 700c, 28", 29" (622mm rim): hybrid / road bike / large-wheel mountain bike
  • 650b, 27.5" (584mm rim): medium wheel mountain bike
  • 26" (559mm rim): mountain bike

You can often find your wheel size by looking for numbering on your tyre, e.g. 26 x 1.75 is a 26" wheel, 622-32 is a 622mm 700c wheel.

The rim

You also need to specify the wheel rim - the metal circle that holds the tyre and which the brakes lock on to. Rim options are:

700c wheels

  • Black (disc brake only, no silvery brake surface)
  • Black with silver (rim & disc brake)
  • Silver with silver (rim & disc brake)

650b wheels

  • Ryde Andra 321 (solid black, disc brake only)
  • Ryde Zac 421 (black with with silver rim brake surface)

26 wheels

  • Ryde Andra 40 (solid black, disc brake only)
  • Ryde Zac19 (black with silver rim brake surface)

You can also specify silver or black spokes.

Cassette options

You can fit your own cassette if you have a specific one in mind or your current one is relatively new and you want to keep the cost down. If you want one fitted, the options are:

  • Single speed - £20.83
  • 7 speed (also works for 5 & 6 speed) - £15.83
  • 8 speed - £18.33 or £24.17
  • 9 speed - £18.33 or £24.17
  • 10 speed - £20.83, £23.33, £26.67
  • 11 speed - £23.33, £26.67, £29.17

(The exact costs depends on how many teeth you want on the biggest rear gear - the more there are, the easier/slower it is to climb. Our cassettes are competitively priced in line with shop prices and a small fitting fee.)

Mounting it

You also need to check that your bike seat post or down tube takes standard bottle-cage mounts as that’s where the battery will go. You can download a frame-fitting check here. Please note that the battery cannot be attached with cable ties as they're not strong enough - you must use the supplied mount, which does not come with frame straps.

Other bike parts

Your upgraded ebike will be slightly heavier and more powerful after the conversion - so you need to think about the rest of your bike. 

If your drivetrain is low-quality or worn, you might find the chain skips under the extra power. 

The extra weight and faster potential speeds also mean the brakes need to work harder. If your bike has caliper brakes with a single pivot we recommend upgrading your calipers to double pivot for enhanced stopping power.

So you might also want to think about servicing or upgrading other parts of your bike. 

Using a shop to fix the kit

You can find a shop to fix your kit for you at https://boostbike.uk/locations. Shops usually charge around £50 to £100 on top of the £649 for the basic kit (plus the cassette fee, see above).

We recommend using a shop to fit the kit if you’ve never or wouldn’t be comfortable changing a wheel. You should also use a shop if your bike may need a parts upgrade (see other bike parts, above) or it’s time for a service. 

Keep your kit in good condition

Noise

Electric bikes make noise - there’s a motor driving you forward. But the Boost kit is quieter than a Lime bike, for instance. They shouldn’t, however, rattle. So ensure there are no loose fittings or nuts. Also, remember that motors tend to be noisier when cycling slowly as they are set up to run most efficiently at higher speeds.

Wet and dry

The Boost kit warranty does not cover damage caused by water , and like most conversion kits it is not rated for cycling in the rain.

We sell a cover (£20) for the battery and controller if you do want to cycle in the rain. Having said that, as long as you don’t power wash it or cycle in heavy rain without a cover, you will generally be OK. Please do not use a pressure washer or hose pipe anywhere near the Boost controller or motor.

Which bikes can I fit a conversion kit to?

You can fit the Boost kit to most road, hybrid or mountain bikes with 700c or 26/27.5-inch wheels, including those with v-brake, cantilever, caliper and disc brakes and suspension. It works with carbon, steel and aluminium frames.

Not sure which kit to choose - read about Boost vs Swytch kits.

Conversion kits we’re currently developing

Conversion kits shouldn’t be used for folding bikes unless specifically designed to. The folding process and bracket can damage the wiring, and it’s hard to position the controller without compromising the foldability. Boost has a conversion kit specifically designed for Brompton bikes.

The kit does not work with smaller bikes although we are developing one for Brompton bikes. We are also developing one to work with through axle bikes - higher priced bikes made since 2018. Boost does not work with roller-brake models as roller brakes cannot be fitted to the motor. 

Ebikes and the law

The Boost kit is fully compliant with UK law. Do not buy a kit where:

  • The motor is greater than 250W
  • The assistance is given when you are not pedalling (EG it has a throttle)
  • The assistance carries on once you reach 15.5mph

Converted bikes that don’t meet these rules essentially count as motorbikes - so you’ll need insurance, a driving licence and there are limits on where you can use them. The police can confiscate them and you can get points on your licence for riding them.