Rally app or tripmaster? What you actually need

To get started in regularity rallies, a good rally app on your phone's GPS is enough. A classic tripmaster with a wheel sensor has the edge if you often drive through forests and tunnels, want your distances to match the organiser's measurement exactly, or the regulations do not allow GPS devices. Here is an honest comparison.

What a tripmaster does

A tripmaster is a permanently fitted measuring instrument. Depending on the model, a sensor picks up distance from a wheel, the gearbox or the speedometer cable. Because it counts wheel turns, it does not need satellite reception.

Through calibration on the calibration route, you match it to the organiser's measuring car. Simple units only show trip and total distance. More advanced rally computers also work with average speed and target time.

What a rally app does

A rally app runs on your phone and measures distance by GPS. Rally Co-Pilot, for example, works out your target time from average speed and distance, counts it down and shows your live deviation in metres or seconds. You see straight away whether you are ahead of or behind target.

On top of that, it has features a classic instrument does not:

• AI roadbook scanner: Photograph a roadbook or speed table page and the app turns it into sections with distance and target speed. You review everything before importing. It runs entirely on the iPhone and needs iOS 26 and a device with Apple Intelligence.
• Apple Watch: Countdown, time deviation and speed on your wrist while the iPhone stays in its mount.
• Remote triggers: Start with the volume buttons, a Bluetooth camera remote, or a PlayStation or Xbox controller. The controller can also stop a test.
• Live Activities: Remaining time, average and distance on the lock screen.
• Timers: As many stopwatches and countdowns as you like, for example for time controls.

Side by side

Criterion	Tripmaster	App with iPhone GPS	App with RaceBox
Installation	Sensor, wiring, mounting	None	None, pairs via Bluetooth
Distance measurement	Wheel sensor	GPS	GPS at 25 updates per second
Forest, tunnels, deep valleys	Independent of reception	Reception can suffer	Still needs open sky
Matching the roadbook	Adjustable via correction factor	Can differ from the measurement	Can differ from the measurement
Live target time and deviation	Depends on model	Yes	Yes
Changing cars	Needs refitting	Phone moves with you	Phone and RaceBox move with you
Regulations	Depends on class	Depends on class	Depends on class

When a tripmaster is the better choice

Be honest with yourself. In these cases, a wheel sensor makes a lot of sense:

• You compete to the hundredth and your rallies often run through dense forest, tunnels or narrow valleys. GPS can struggle there. A wheel sensor does not.
• Your regulations ban GPS. Some events or classes restrict GPS devices and smartphones. Read the regulations carefully.
• You want to match the organiser's measurement exactly. With a correction factor, your odometer effectively counts like the measuring car. GPS measures the distance you actually drove, which can differ slightly.
• One car, many rallies. A permanent installation that is always there is worth it.

When the app is enough, or even better

• You are just starting out. You want to find out whether you enjoy the sport before fitting hardware.
• You switch cars. The phone simply comes along.
• You do not want to alter the original. No drilling, no wiring in a historic vehicle.
• You want to see live where you stand. Deviation in metres or seconds helps you correct early instead of guessing.
• You want less typing. The roadbook scanner saves entering speed tables just before the start.

The middle ground: app plus RaceBox

If your iPhone's GPS feels too slow, you can connect a RaceBox Mini, Mini S or Micro via Bluetooth. It delivers 25 position updates per second. If its signal drops, Rally Co-Pilot switches back to the iPhone's GPS automatically. Subscribers get a 20 percent discount code for the RaceBox store.

To be fair, though: a RaceBox is still a GPS receiver. In a long tunnel it has no reception, just like the phone.

Common misconceptions

• "GPS is too inaccurate for rallies." On open roads, modern GPS is good. The weak spots are poor reception and the gap to the organiser's measurement.
• "A tripmaster does all the maths for me." Basic units only measure distance. You then work out time yourself with an average speed table and a stopwatch.
• "I need both." Maybe, maybe not. Plenty of crews combine a tripmaster for distance with an app for time and countdown.

How to decide

1. Read the regulations for your next rally: what is allowed in your class?
2. Look at the route: lots of forest and tunnels, or open country?
3. Start with the app and drive the calibration route too. You will see how well the GPS distance matches the official one. More in How to calibrate your odometer.
4. If you keep losing points to distance errors, a tripmaster is the next step.

To learn how organisers do their own timing, read How rallies measure time. New to all this? Start with Your first classic rally. And your next chance to try it out is waiting in the rally calendar.