How to Read Your Racing Line From GoPro Footage

Short version: the GPS in your GoPro already records your line, about ten fixes a second. Race Ninja draws it on a map of the circuit, colours it by speed, and lets you lay two laps on top of each other. You don't need a logger for this. You need the original file and twenty minutes.

What the line on the map is

Every dot is a GPS fix. Join them up and you get the path the kart took, not the path you meant to take. That gap is the whole point. Most drivers remember a clean apex. The map shows a turn-in two metres early and a kart that ran out of road on the way out.

The line is coloured by speed, so you can see where you were slow without reading a graph. Corners are numbered, and each one has its own entry and exit speed, so Turn 4 on the map is the same Turn 4 in the sector times and in the coaching notes.

Where to look first

Entry. Where does the colour change from fast to slow? That's your braking point. Compare it across laps. If it wanders by a kart length from one lap to the next, you're not braking to a reference yet.

Apex. Zoom in. Is the line touching the inside kerb, or is there a gap? A gap at the apex means the kart turned in late or carried too much speed in. Both cost you on the way out.

Exit. Does the line use all the road? On most kart circuits the fast laps run out to the edge and the slow ones stay a metre inside it. That metre is a tighter radius, which is less speed down the whole of the next straight.

The straight after. Look at the speed at the end of the straight, not in the corner. Exit speed compounds all the way to the next braking point. A tidy exit from a slow hairpin is worth more than a brave entry.

Compare two laps, not one

One lap tells you what you did. Two laps tell you what mattered. Open Head to Head, put your best lap against a slower one from the same session, and watch where the two lines separate. The sector times underneath tell you which corner the gap opened in. Take the biggest delta and ignore the rest for now.

And don't only compare best against worst. Two laps within a tenth of each other on different lines are the interesting pair. Same time, different route. One of those routes has more in it.

Where the time hides

Time goes missing in the same places session after session. Long corners where the kart turned in early and scrubbed speed through the middle. Chicanes driven as two corners instead of one line. Exits where the throttle came late because the kart wasn't pointing straight yet. Each of them shows up as a dip in the speed colour that your faster lap doesn't have.

A worked example

Say your best lap is a 52.4 and your Perfect Lap, the one stitched from your fastest sector in each part of the track, reads 51.9. That half second is already yours. You drove every piece of it, just not on the same lap. The sector table tells you which lap each piece came from, so you can open that exact corner on that exact lap and see what you did differently. Usually it's a later apex and an exit that used the whole road.

What you need

GPS switched on, a satellite lock before you roll, and the original file off the SD card. Exports from editing apps and share menus lose the GPS track, and then there's no line to read. Not sure whether your file still has it? The GPS checker tells you in your browser without uploading anything.

Upload a session and read your own line, or check the cameras that record GPS first.