Contents01/07How does an e-bike tuning kit work?
Under EU rules an e-bike motor only assists up to 25 km/h. Above that the assistance cuts out and you pedal on your own. An e-bike tuning kit is a small device that changes the speed sensor signal so the motor keeps assisting at higher speeds.
How does an e-bike tuning kit work?
The motor controller calculates speed from the rear wheel sensor. A tuning kit recalculates that signal – for example halving it – so the controller thinks you are riding slower and does not cut the assistance. Importantly, a tuning kit does not increase motor power. The motor works exactly as it did from the factory; the assistance just no longer stops at 25 km/h.
Many modern kits (such as SpeedBox B.Tuning) have a Bluetooth app that shows your real speed and trip data and lets you switch the kit on or off.
How fast can a tuned e-bike really go?
The top speed with a tuning kit depends on your cadence and gearing, not on the kit itself. You can calculate it:
Speed (km/h) = cadence (rpm) × wheel circumference (mm) × front chainring teeth ÷ rear sprocket teeth × 60 ÷ 1,000,000
In practice most tuned e-MTBs ride at 30–45 km/h depending on gearing, gradient and rider strength. Some kits let you set the speed at which assistance stops.
Electronic vs mechanical kits
- Electronic (wire-based) kits connect between the motor and the speed sensor (SpeedBox, PearTune, VOLspeed, BadassBox, SpeedFun). They sit under the motor cover and often come with an app.
- Mechanical kits such as SPEEDi mount at the rear brake disc and mechanically change how the sensor magnet rotates. No wires or electronics.
For a detailed comparison see Wire-based vs mechanical e-bike tuning kits.
Is a tuning kit worth it?
A tuning kit is most worthwhile for riders who:
- feel held back by the 25 km/h limit on trails and private land;
- ride longer distances on private land and want smooth assistance at higher speeds;
- want assistance that does not cut out on fast descents or flat sections.
If you mostly ride on cycle paths and public roads, a tuning kit is not for you – a modified e-bike may not be used there. More in Is e-bike tuning legal?
Can you remove a tuning kit?
Yes. Almost all kits are reversible: electronic kits disconnect without leaving changes, and the mechanical SPEEDi is removed by refitting the original magnet. Many riders switch the kit off or remove it when riding where the 25 km/h limit applies.
Does tuning harm the motor or battery?
A tuning kit does not add power, but at higher speeds the motor works for longer and the battery drains faster. We cover this separately in Does e-bike tuning damage the motor or battery?
How to choose the right kit
A kit is chosen by motor (Bosch, Shimano, Yamaha, Brose / Specialized, Giant, Bafang and others), sometimes also by display or model year. See all options in our tuning kits by motor collection and our picks in the best tuning kits by motor. Not sure which one fits your bike? Send us a message and we will help.
