Boost Through Axle Conversion

After a year of development and design, we're delighted to be the first company to be able to upgrade your through-axle frame bike to electric! Our brand new, patent-pending motor is only available from Boost.

Save £50 now!

The full price will be £699 (includes UK VAT) for the through-axle conversion system - we're offering through May at only £649, the same price as the regular Boost kit! You can specify your wheel build from the Full Size Boost Kit order page.

Our new Boost motor makes use of the commonly adopted shape of through-axle dropouts to provide both weight & torque transfer.

Compatibility check

  1. Your bike should be a 142mm x 12mm type. 148mm x 12mm are not yet available.
  2. The attachment points on the frame must be alloy; it's ok if the bike frame is carbon, as long as the frame has alloy pieces for the axle attachment. We do NOT recommend use on the rare bike where the attachment points are themselves moulded from carbon.
  3. Your removeable axle should be M12 / 12mm diameter and fully removeable, and once removed leave a hole fully visible through the frame.

Here's a very simple view of a compatible type of frame. Both sides of the frame have 19mm slots; the left dropout has a 12mm hole, the right has a threaded 12mm hole.


Please do carefully read this guide before attempting installation of the wheel. Particular care should be taken to avoid scratching the motor on the dropouts, or damaging the cable on the brake rotor or by catching it in on the frame. If you have any doubts at all please get in contact with us or a shop.

We have a dedicated Facebook forum for this through-axle conversion - please join!

Facebook Boost Bikes - Through Axle Project

Brake size

Note that if you are installing on a disc-brake bike, you will need at least a 160mm rotor to avoid clearance problems with the caliper. Adapters are available from normal bike parts specialists to move calipers from 140mm rotor position to 160mm position.

In the box

The motor

Our new motor is based on our conventional-axle core with a brand new, 32 hole shell. It features an innovative axle design compatible with through-axle frames.

Add spacers & torque washers to fit the frame.

Left Spacer (3 included)

The goal is to use as few spacers as possible. However, they made be necessary to move the motor away from the frame.

The left washer has a special shape so it will only fit on the left, and it has a cutout to avoid damage to the cable that runs past it.

DO NOT FIT a Right Spacer on the left side of the motor.

Right Spacer (3 included)


Fit sufficient right spacers to create sufficient clearance between the cassette lock ring and the frame.

Torque Washers (2 supplied)

Once spacers are fitted on left & right side, fit one torque washer on each side.

The 'wings' of the torque spacer must be on the outside of the axle to engage with the dropout or frame.

Skewer & skewer nuts

Details coming soon.

Installation process

This is not meant to be an exhaustive list. If you run into problems contact - do not force it.

  1. Remove existing wheel. Fit disc rotor (6 bolt, minimum 160mm rotor) to Boost motor - remove plastic disc-spacer & retain (this plastic spacer must not be left in place when a rotor is installation. Lightly tighten disc rotor bolts - this is just for trial fit.
  2. Offer the motor to the frame to check it vaguely fits and that the frame can be gently sprung open sufficiently to accept the axle width.
  3. Fit cassette & lock ring as usual - you may wish to lightly tighten only for trial fit.
  4. Fit Left & Right Spacers by pushing on - they are meant to have an interference fit so you may need to use a 12mm socket with a rubber mallet to tap them into place.
  5. Fit torque washer on each side (wings outboard, touching frame).
  6. Use a 5mm skewer with one of the supplied skewer nuts to fasten the motor into place.
  7. Once you're happy with the fit, tighten everything up.

Do not over-tighten the quick release skewer; if it is over-tightened it may damage the motor. Reasonable hand strength is sufficient, do not use tools.

Returns & refunds

This is a new product and as such as can offer special terms for refunds if it does not fit your bike. (Usually we are not able to offer refunds in any circumstance because all wheels are custom made.)

Please check your motor fits in your frame before fitting a tyre (or indeed building a wheel). If you wish to return the motor unused we will be to refund with a small restocking & postage fee as long as it's in mint condition. Any marks or damage to the cable will mean that we are regrettably unable to offer a return and if you have already returned the motor to us, we will charge you a return postage fee to send it back to you.

If we supply a custom wheel for you, it is very unlikely that we can offer a return in any circumstance. We would only consider a refund if you have already send us a photo of your frame and we have confirmed it will fit.

If you are uncertain about your bike mechanic skills, please do not attempt fitting and ask your Boost partner shop to do it for you. Damage caused by errors with installation will mean that we cannot offer a return.