We bought a RaceBox Mini S to test it as a data source for Kurvenfokus. The result: it's far more than a GPS logger. 25 Hz multi-GNSS, a 6-DOF IMU with gyroscope and accelerometer, lean angle and G-forces in the export. But on a motorcycle there's a trap in the lean-angle measurement. And: RaceBox provides an open Bluetooth protocol — the basis for our planned real-time integration.
Why we bought a RaceBox Mini S
Kurvenfokus analyses motorcycle tours — corners, lean angle, G-forces, tour score. So far exclusively from GPS data, recorded by smartphone at 1 Hz. That's enough for tour analysis, but for fast direction changes and on the track the resolution is missing.
The RaceBox Mini S promised 25 Hz GPS — 25× more measurement points. At 60 km/h that means a point every 67 centimetres instead of every 17 metres. We wanted to know: what does that bring in practice? And what's really inside?
What's inside: more than expected
First surprise after unboxing and looking at the specifications: the RaceBox Mini S is not a pure GPS receiver. It has a full 6-DOF IMU built in.
| Sensor | Specification | Meaning |
|---|---|---|
| GNSS receiver | 25 Hz, GPS + GLONASS + Galileo + BeiDou + SBAS | Position and speed with sub-metre precision |
| GPS antenna | -167 dBm sensitivity, 20 dB gain | Stable reception even in narrow valleys |
| Accelerometer | ±8 g, 0.001 g resolution, 1 kHz internal | G-forces under braking, acceleration, in corners |
| Gyroscope | ±320 °/s, 0.02 °/s resolution, 1 kHz internal | Rotation rate around all 3 axes — basis for lean angle |
| Magnetometer | Not fitted | Heading only via GPS course angle |
| Barometer | Not fitted | Altitude only via GPS (±10 m) |
Accelerometer + gyroscope form a 6-DOF IMU — the same sensor type as in professional data loggers. Internally the RaceBox samples at 1 kHz (1,000 measurements/second), the data is filtered and output at 25 Hz.
Measuring lean angle: the motorcycle trap
The RaceBox measures lean angle — in the app and in the VBO/CSV export. But on a motorcycle there's a fundamental problem we had to understand.
The problem: the IMU leans with the bike
In a car the chassis stays roughly horizontal through a corner. The IMU measures the lateral force correctly. On a motorcycle it's different: the device leans into the corner with the bike. The IMU can't tell whether the measured force comes from centrifugal force or from the gravity component due to the lean. The result: the IMU-based lean angle underestimates by about 15 %.
Two calculation methods
- IMU lean (directly measured): from gyroscope + accelerometer. Fast response (1 kHz), but ~15 % underestimation on a motorcycle. Good for relative comparisons between corners.
- GPS lean (calculated): from speed + rate of course change → the physically required lean angle. For motorcycles at 25 Hz often more accurate than IMU lean — because the calculation doesn't have the lean problem.
The RaceBox app and RaceChrono both offer both methods. Our recommendation for motorcycles: use GPS lean — at 25 Hz the resolution is high enough for precise corner analysis.
Export formats: where's what?
One point that cost us time at first: not every export format contains all the data.
| Format | Position | Speed | Lean angle | G-forces |
|---|---|---|---|---|
| VBO | ✓ 25 Hz | ✓ | ✓ | ✓ |
| CSV | ✓ 25 Hz | ✓ | ✓ | ✓ |
| GPX | ✓ | limited | — | — |
| KML | ✓ | — | — | — |
VBO is mandatory for motorcycle telemetry. Anyone who only exports GPX gives away the entire IMU dataset — lean angle and G-forces are lost. Kurvenfokus imports VBO files on iOS.
Mini vs. Mini S: what sets them apart?
We deliberately chose the Mini S. The reason is simple: standalone recording.
| Property | Mini | Mini S (our device) |
|---|---|---|
| Sensors (GPS, IMU) | Identical | Identical |
| Internal storage | None | 130 min @ 25 Hz / 325 min @ 10 Hz |
| Standalone recording | Needs permanent Bluetooth | Records without a smartphone |
| Price (as of 06/2026) | ~€200 | ~€260 |
On a motorcycle the Mini S is clearly the better choice: stick it magnetically on the tank, switch it on, ride off. No Bluetooth to the smartphone needed, no risk of the connection dropping under vibration. You transfer the data after the ride.
What the RaceBox lacks
Two sensors that smartphones have as standard are missing from the RaceBox:
- Barometer: altitude only via GPS → ±10 m variation. On pass rides the altitude profile is jagged and useless for precise elevation figures.
- Magnetometer: heading only via GPS course angle. At a standstill or low speed: no heading available.
No problem for corner analysis and lap times. If you also need precise altitude profiles, you can run MotionRecord on your smartphone in parallel.
The open Bluetooth protocol
What sets the RaceBox apart from many competitors: RaceBox provides complete Bluetooth protocol documentation for developers. No reverse engineering, no closed API — an official specification describing how to receive the sensor data in real time via Bluetooth Low Energy.
We requested the documentation and received it. For a hardware product in this price range that's unusual — and a strong signal to the developer community. Closed ecosystems are sadly the norm in motorsport hardware.
Our next step: a direct Bluetooth integration in Kurvenfokus. Instead of VBO export → import, the app could receive the RaceBox data in real time — 25 Hz GPS + IMU straight into the corner analysis, without the detour via files. That's still in planning, but the technical foundation is there.
Our verdict after the first test
The RaceBox Mini S surprised us positively. Not because of the GPS quality — that was expected. But because of the IMU that almost disappears in the spec sheet. Gyroscope and accelerometer with a 1 kHz internal sample rate, lean angle and G-forces in the VBO export — that's remarkable for ~€260.
You have to be aware of the motorcycle trap in the lean-angle measurement. But with GPS lean at 25 Hz you have an alternative that's more accurate than any 1 Hz smartphone calculation.
And the open Bluetooth protocol makes the RaceBox the ideal partner for Kurvenfokus. Not because it can do everything — but because it can be integrated.
The RaceBox Mini S was bought and paid for by us. No sponsorship, no review unit. Technical specs: racebox.pro (as of June 2026).