Why electric bike tuning kits could put you on the wrong side of the law and void your warranty

In our Tech Q&A series, BikeRadar tackles your cycling questions – no matter how easy or difficult, ultra-nerdy or beginner-friendly – with insights from our tech team and trusted industry experts. This time, a reader wants to know whether off-the-shelf ebike tuning kits are legal, and how they'll impact his warranty.

First off, although the kits themselves are not illegal, fitting one of these kits to your ebike would likely make it illegal to ride in most places in the UK.

If the motor does not cut off once you reach the 25km/h (15.5mph) speed limit, this means the bike is no longer classified as an EPAC (for more information, read our guide to electric bike laws). As such, it is likely to be considered a moped or speed pedelec. Like mopeds, they can only be ridden on roads or unrestricted byways, but they must also be taxed and insured, you must have a licence and you need to wear a motorcycle-style helmet to ride them.

Bearing that in mind, SpeedBox says modified bikes are designed to be used only off-road on private land: "E-bikes equipped with SpeedBox are not allowed on public roads, cycling paths, or public places. They are intended for use on private property and at your own risk," reads the disclaimer on the SpeedBox website.

The risks continue with implications for insurance and public liability should you crash while riding a modified bike.

Legal considerations aside, SpeedBox claims its upgrade kits won’t damage your motor, but Shimano disagrees – and at the very least, it will void your warranty.

Madison is the UK distributor for Shimano. A Madison spokesperson said: “Whilst these kits are unfortunately still legal, there are serious ramifications for the user – and not just from a safety perspective. Any use of these aftermarket kits instantly voids your warranty here in the UK."

Naturally, SpeedBox disagrees – in a statement to BikeRadar, a SpeedBox spokesperson said: "Using SpeedBox does not damage the bike, we have been [selling conversion kits] for various brands and so far nothing like this has happened."

Installing one of these kits could impact firmware updates. Modern software may be able to detect the presence of a tuning chip, so you will likely need to remove it before servicing or installing updates from the manufacturer. 

• Read more: Bicycle insurance 2025: Do cyclists need insurance?

Ultimately, we wouldn’t advocate using these kits – in the UK, at least, you're limited to using them on private land if you want to stay on the right side of the law, but they're hardly worth the risk.