How it works
Film like you already do
GoPro with GPS on, or a DJI with its GPS remote. Nothing extra mounted, nothing to charge.
Upload after the session
From the browser or the Windows uploader. The GPS is already in the footage.
Get the full picture
Lap times, sectors, lines and coaching notes, each one linked to the moment on film.
Why footage beats a phone app
Ten times the position fixes
A phone lands one GPS fix a second, a 25-metre blind spot at kart speed. A GoPro lands ten, cutting that to a couple of metres. That resolution is what your lap and sector precision rides on.
Built for the kart, not your pocket
Vibration, engine heat and the occasional shunt kill phones. Action cameras shrug them off. You're mounting kit designed for exactly this, not risking a £1000 handset.
Video attached to every lap
A timing app tells you lap 7 was your best. The footage shows you why. Every sector time links to the exact seconds of video that produced it.
Coaching, not just times
Times tell you that you were slow. The coaching notes tell you where, and what to try next time out.
Common questions from lap timer app users
Why is a phone a poor lap timer?
It comes down to how often the GPS updates. An iPhone fixes its position about once a second. A kart at 90 km/h covers 25 metres in that second, so between one fix and the next the phone has no idea where you are for 25 metres of track. That's most of a corner. A GoPro logs its position ten times a second, which drops that blind gap to roughly 2.5 metres. Ten times the sampling. The finer it samples, the more precisely a lap or sector time can be placed, and a phone samples too coarsely to trust to the hundredth.
Won't a 25Hz external GPS puck beat a camera?
It's diminishing returns, and this is where the maths turns against the puck. Going from a phone's one fix a second to ten is the leap that counts: the kart's blind spot between fixes falls from 25 metres to about 2.5. Push a premium puck to 25 fixes a second and that gap only tightens from 2.5 metres to one. By then you're sampling your position faster than the GPS can actually find it, because each fix still carries a metre or two of its own error no matter the rate. So the extra Hz mostly lands inside the noise. And you've paid for a second device to charge, pair and keep in Bluetooth range, with your phone still bolted to the kart. A GoPro gives you the 10Hz that matters plus the footage synced to every point, in one unit.
Do I really want my phone on the kart?
Probably not. A race kart is brutal on electronics. Constant vibration, heat coming off the engine, the odd shunt into the barriers. Phones aren't built for any of that, and a cracked or dead £1000 handset is an expensive way to time a lap. Action cameras are designed to be bolted to moving things and thrown around. That's the whole point of them.
Is there an alternative to RaceChrono for karting?
Race Ninja, if your camera has GPS. RaceChrono is a proper tool and good at what it does, live timing from your phone or an external GPS box. Race Ninja skips the phone entirely: the camera you already film with records the data, and the analysis, sector times and coaching come back after you upload.
Does Race Ninja do live lap timing?
Not on the kart, no. RaceChrono shows times as you drive; Race Ninja works after the session, from the footage. What you get in exchange is video attached to every data point, sector analysis and coaching notes, which a live timer can't give you.
Can I compare my laps against other drivers?
Yes. Circuit leaderboards are built from verified onboard footage, so every time on there was actually driven, on video. Phone-app times rely on trusting the setup.