Why is one racing line faster than another?
Drag the line. The physics recalculates. See exactly where the time is won and lost.
Late apex turns in 3.0 m later, apexes 1.8 m away and tracks out 5.0 m later than Geometric apex. Only a few metres, yet 0.17 s apart: small changes in line, big changes in time.
Same car. Same corner. Two lines.
| Line | Brake & corner | Straight | Total |
|---|---|---|---|
| Geometric apex | 0.00 | — | 0.00 |
| Late apex | 0.00 | — | 0.00 |
Seconds. "Brake & corner" runs from the start to the corner exit; "Straight" is the 90 m run to the finish.
- Late apex is 0.14 s behind at the corner exit.
- But it carries more speed down the straight, 6.6 mph faster at the finish line, and wins back 0.31 s.
- Late apex wins by 0.17 s.
- Late apex only needs about 40 m of straight to make up the time.
Live result from the physics model, replayed at 60% speed. Nothing is scripted: change the car or the lines and the winner can change.
Try it yourself in Line Comparison →Three experiments
Cornering Physics
How fast can you really take a corner?
Play with radius, grip and speed, and see why a wider arc lets you carry more speed.
2Line Geometry
What does moving the apex actually change?
Drag the turn-in, apex and track-out points and watch the tightest radius and speed limit move.
3Line Comparison
Can a slower corner give you a faster lap?
Race two lines with the same car, see where time is won and lost, and how the next straight changes the answer.
Who it's for
Sim racers
Understand why the fastest lap uses the line it does, and when breaking the rule pays off.
Track-day drivers
Explore the trade-offs between entry speed, apex and exit on screen before you think about them on track.
Motorsport fans
Know what it really means when a driver "compromises the entry for a better exit".
How it works
- Real calculations. Every speed and time comes from a model of tyre grip, braking and acceleration. No line is coded to win.
- Runs in your browser. Nothing to install, no account, and your experiments stay on your device.
- Honest limits. A simplified car on a flat, dry track: great for building intuition, not a lap-time predictor.