This glossary explains the words you will hear on a circuit, in one plain sentence each. You do not need to know any of them before a Stratos event. Your coach will teach them as they come up.
In short: The racing line is the fastest path through a corner. The apex is the point where you are closest to the inside. Braking in a straight line comes first; trail braking comes later. Flags are how marshals talk to you: yellow means slow down, red means stop.
The corner
- Racing line: the fastest path through a corner, usually wide on the way in, close to the inside in the middle, and wide on the way out.
- Turn-in: the point where you begin to steer into the corner.
- Apex: the point where the car is closest to the inside of the corner.
- Late apex: touching the inside later than the geometric middle, which lets you use the power earlier on the way out.
- Track-out (exit): where the car drifts back to the outside edge as you unwind the steering.
- Braking point: where you start to brake for a corner.
- Reference: a fixed marker, such as a board or curb, that you use to brake or turn in at the same place each lap.
- Curb: the raised, painted strip at the edge of the track.
- Run-off: the open area beyond the track edge that gives you room if you go wide.
Types of corner
- Hairpin: a slow corner that turns back on itself.
- Chicane: a quick left-right or right-left sequence built to slow cars down.
- Esses: flowing left-right bends taken as one movement.
- Sweeper: a long, fast corner with a steady radius.
- Blind crest: a rise that hides the track beyond it.
- Banked corner: a corner tilted toward the inside, which adds grip.
Braking and power
- Threshold braking: braking as hard as the tires allow without locking.
- Trail braking: easing off the brake gradually as you turn in, to keep weight on the front tires.
- Weight transfer: how the car's weight moves forward under braking, back under power and sideways in a corner.
- ABS: the system that stops the wheels locking under hard braking.
- Traction control: the system that limits wheelspin under power.
- Paddle shift: changing gear with paddles behind the steering wheel, with no clutch pedal.
- Naturally aspirated: an engine with no turbocharger, such as the flat six in a Porsche 911 GT3.
Grip and balance
- Grip: how much force the tires can take before they slide.
- Understeer: the front tires slide and the car turns less than you asked.
- Oversteer: the rear tires slide and the car turns more than you asked.
- Downforce: air pressing the car onto the track, adding grip at speed.
- DRS: a drag reduction system; a rear wing that opens on straights for more speed, as on the Porsche 911 GT3 RS (992).
- Semi-slick: a road-legal tire with very little tread, built for circuits.
- Tire pressures: checked through the day because they rise as the tires heat up.
The lap
- Out lap: your first lap after leaving the pit lane, used to warm the tires and brakes.
- Flying lap: a lap at full pace.
- Cool-down lap: a slower final lap to cool the brakes and engine.
- In lap: the lap that brings you back to the pit lane.
- Sector: one of the sections a lap is divided into for timing.
- Pit lane: the lane beside the track where cars stop, with its own speed limit.
- Open pit lane: a format where you can enter and leave the track when you like.
- Session: a set period of time on track.
The flags
| Flag | What it means | What you do |
|---|---|---|
| Green | Track clear | Drive |
| Yellow | Danger ahead | Slow down, no overtaking |
| Double yellow | Serious danger, track may be blocked | Slow right down, be ready to stop |
| Red | Session stopped | Slow down, return to the pit lane |
| Blue | A faster car is behind you | Let it pass |
| Yellow and red stripes | Slippery surface | Take care |
| Black | You, specifically | Return to the pit lane |
| Checkered | Session over | Finish the lap, return to the pit lane |
The people
- Coach: the professional driver who teaches you, from the seat beside you.
- Marshal: the trained official at each post who shows the flags and helps if a car stops.
- Safety crew: the circuit's rescue, medical and recovery teams.
The tools
- Onboard video: a camera in the car, used to review your driving.
- Data (telemetry): recordings of speed, braking, throttle and steering.
- Speed trace: a graph of your speed around the lap.
- Simulator: a rig that lets you learn the circuit before you drive it.
- Briefing: the talk before driving that covers safety, flags and the plan.
Formats
- Track day: circuit time for road cars, with no racing.
- HPDE: High Performance Driver Education, the American instructed track day.
- Private circuit hire: the whole circuit reserved for one group.
- Hot lap: a fast lap as a passenger with a professional driver.
How track coaching works · Your first track day checklist · See upcoming events
FAQ
What is an apex?
The point in a corner where the car is closest to the inside edge.
What is the racing line?
The fastest path through a corner: wide in, close to the inside at the apex, wide out.
What is trail braking?
Releasing the brake gradually as you turn in, to keep grip on the front tires.
What is the difference between understeer and oversteer?
In understeer the front slides and the car runs wide. In oversteer the rear slides and the car rotates.
What does a yellow flag mean on a track day?
Danger ahead. Slow down and do not overtake.
What does a blue flag mean?
A faster car is behind you. Let it pass.
Do I need to know these terms before a track day?
No. At Stratos your coach explains each one in the car, when you need it.
About Stratos
Stratos runs exclusive driving experiences at Europe's greatest Grand Prix circuits, for founders and leaders. Each event privately hires the entire circuit for 15 drivers max, with a supercar fleet, private coaching with professional race drivers, 3 nights of luxury accommodation and 2 full track days. Stratos is invitation-only.