The paddock notebook
that knows the track.
Apex Lines is a track-day notebook with the circuit built in: log sessions, pressures, and setup against real maps of 38 circuits — numbered corners, your own reference points, and a computed reference line to study before you ride. Offline-first, no account, one app on iPhone and Mac.
38 real circuits reference line computed from geometry offline-first · no account
Computed, not sketched.
Most track maps come with an artist's swoosh. Apex Lines runs a minimum-curvature optimization over each circuit's real pavement corridor — a reference line to study and adapt, not the line you must ride.
Minimum curvature
The reference line is the solution to a math problem — the smoothest path the pavement allows — not a hand-drawn suggestion. Same method, all 38 circuits, no house style.
Apexes with reasons
Every apex falls where the math clips the corner on the mapped pavement. Late apexes emerge from the track shape — a geometric reference to study, then adapt to conditions, traffic, and your event's rules.
Contained on asphalt
The solver works inside the track boundaries, so the line never cuts grass or hangs over a kerb that isn't there. If it's on the map, it fits on the pavement.
Watch a lap fly itself.
Every circuit renders as a full 3D scene, and fly-the-line mode runs a simulated lap over the reference line — braking into corners, driving out of them — with a live HUD the whole way around. Physics-simulation estimates, not measured data — never a claim about your lap.
- Grip, braking and drive limits shape the speed profile — and you can tune them.
- Live HUD: speed, ride state, and the next corner coming at you.
- Flip between the 2D map and the 3D scene on any track.
Pro · 3D scene and fly-the-line
Every corner, briefed.
Each turn gets a guide derived from the line's curvature: radius, arc, run-up, and the classic racecraft reference points — brake, turn-in, apex, exit — so you walk the track before you ride it. Study material, not rider coaching.
- Per-corner radius, arc and run-up, measured from the computed line.
- Brake / turn-in / apex / exit references on every corner.
- Corner notes attach to the same map — walk it with your coach, mark your own references, and your experience layers onto the geometry.
Pro · corner guides
A notebook that lives at the track.
Track days hold sessions, sessions hold laps. Log times with a stopwatch-style field built for gloves-off pit lane moments, tag cold and hot tire pressures and weather, pin notes to corners on a mini map — then watch the trend line fall.
- Lap trends charted per track, with personal bests tracked automatically.
- Cold and hot tire pressures, weather, and per-corner notes on every session.
- Prep checklists with per-category progress — the laminated sheet, digitized.
- Ride time feeds the Garage: engine hours and tire heat cycles accrue on the bike you rode, so maintenance status fills in from the days you logged.
- One-handed flow on iPhone; a three-pane logbook on Mac.
The notebook pays you back: setup recall when you return to a circuit ("LAST TIME HERE — F 30.0→33.5"), cold→hot pressure deltas per wheel, checklists that carry forward day to day, and single-day CSV/JSON export for everyone.
Free for your first track day · Pro · unlimited
OCT 12 · 3 SESSIONS · 14 LAPS
- S2 · LAP 42:05.31
- S3 · LAP 22:03.88
- S3 · LAP 5 PB2:02.47
The night before is part of the day.
Every planned day sits on one calendar — tap it open, or press and hold to edit or clear it. Then plan the parts a lap timer never sees: where you sleep, when your group rolls out, and whether the bike is locked down for the night.
- Overnight plan per day — paddock camp or hotel — with a security checklist that leads with the alarm and disc lock, never an afterthought.
- Run-group timer: enter the day's rotation once and read your roll-out times all day, with an optional reminder 10 minutes before each slot.
- Session focus and debrief on every session card — one thing to work on, and how it went, written while it's fresh.
- Share a setup card: your pressures, gearing, and conditions as one clean image for the group chat.
Overnight and rotation ride the same prep checklist you already pack from — items keep their check state from Thursday night to Friday morning.
GROUP 2 — 9:20 · 10:40 · 12:00 · 1:20 · 2:40
- ALARM & DISC LOCK ON✓
- CHAIN TO SOMETHING SOLID✓
- COVER ON · OUT OF SIGHT—
Your notebook already knows your engine hours.
The Garage is a maintenance ledger keyed to logged track time. Add your bikes — a nickname is the only required field, so the frankenbike is as first-class as the factory model — and the sessions you log become the hours on your oil, the heat cycles on your tires, the days on your chain. Facts, never verdicts: the Garage reports where you stand, and you own every number.
Hours, not odometers
Track bikes rarely have a meaningful odometer — the paddock question is "how many hours on this oil?" Services, checks, and measurements are ledger rows, and ride time accrues against them automatically: "6.2 of 8 h", with timed, estimated, and manual hours labeled apart and auditable down to the day.
Heat cycles follow the tire
Tire sets are components in their own right: cycles accrue from your sessions, and a set keeps its count when it moves between bikes or comes off for the winter. Intervals seed from curated, cited track-duty references — a source and date on every figure — and you accept or edit each number before it counts.
Ready for Saturday
A planned track day gets a readiness view: which components reach your own mark before or during the event, projected from your typical day and labeled as a projection. No red, no "overdue", no push — one calm list, early enough to order parts.
Free for one bike's full ledger · Pro · unlimited bikes. Per-bike PDF + CSV export of the whole history — free, never gated.
38 circuits. Real geometry.
These circuits ship inside the app: real geometry, numbered corners, and a computed reference line on every map. Cards tagged GUIDE also have a written corner-by-corner guide here on the web — the rest live in the app alone.
WeatherTech Raceway Laguna Seca
GUIDE →
Circuit of The Americas
GUIDE →
Road America
GUIDE →
Michelin Raceway Road Atlanta
GUIDE →
Barber Motorsports Park
GUIDE →
Virginia International Raceway
GUIDE →
Sonoma Raceway
GUIDE →
Willow Springs (Big Willow)
GUIDE →
Streets of Willow Springs
GUIDE →
Buttonwillow Raceway Park
GUIDE →
Thunderhill East
GUIDE →
Thunderhill West
GUIDE →
Thunderhill Full Course
GUIDE →
The Ridge Motorsports Park
GUIDE →
Pittsburgh Int'l Race Complex
GUIDE →
NJMP — Thunderbolt
GUIDE →
Mid-Ohio Sports Car Course
GUIDE →
Watkins Glen International
GUIDE →
Sebring International Raceway
GUIDE →
Utah Motorsports Campus
IN THE APP
Chuckwalla Valley Raceway
IN THE APP
Circuito de Almería
IN THE APP
Jennings GP
IN THE APP
Cadwell Park
IN THE APP
Donington Park — GP
IN THE APP
Donington Park — National
IN THE APP
Snetterton 300
IN THE APP
Brands Hatch — GP
IN THE APP
Brands Hatch — Indy
IN THE APP
Phillip Island
IN THE APP
Slovakia Ring
IN THE APP
Broadford — State Moto Complex
IN THE APP
Circuito de Cartagena
IN THE APP
Pannónia-Ring
IN THE APP
Harris Hill Raceway
IN THE APP
TT Circuit Assen
IN THE APP
Mugello
IN THE APP
Circuito de Navarra
IN THE APPTRACK OUTLINES © OPENSTREETMAP CONTRIBUTORS · ODbL
Log at the track. Study at home.
Built for pit lane
A fast, one-handed flow for the ten minutes between sessions: punch in lap times, tire pressures and weather, drop a note on the corner that's bugging you. Fully offline — paddock signal doesn't matter.
Built for homework
A three-pane logbook with lap-trend charts, and the whole track library on a big screen — walk the line corner by corner and plan the next day out. One purchase covers both platforms.
No account to create. Your notebook is stored on-device and syncs between your iPhone and Mac through your own iCloud.
One app. Two companions on the web.
Apex Lines is the notebook. The web products stand on the same real track geometry — no app required.
Corner-by-corner, written.
Entry, minimum and exit speeds, brake points, radii and elevation for every corner of 19 circuits — computed by physics simulation over real geometry, then written up. Three full guides free.
Read the guides → Line LabThe line, solved live.
An in-browser lap simulator on the same geometry: pick a circuit, tune the bike class, and watch the speed profile re-solve as you ride the sliders. Free to try.
Open the Lab →A free tier that's actually useful.
Every circuit and every reference line is free. Pro opens the rest of the toolbox.
- Your first track day in the notebook
- The Garage: one bike's full maintenance ledger
- Track-day prep checklists and references
- All 38 circuits, with search and filters
- 2D maps with the computed reference line
- Metric or imperial, app-wide
- Everything in Free
- 3D scenes + fly-the-line simulation
- Corner guides on every turn
- Unlimited notebook
- Unlimited bikes in the Garage
- Everything in Pro Monthly
- One season, one payment
Prices in USD; local pricing may vary. Subscriptions bill through your Apple ID and renew until cancelled — manage or cancel anytime in Settings. One subscription covers iPhone and Mac.
Fair questions.
Is Apex Lines a GPS lap timer?
No — and that's deliberate. Apex Lines is the study-and-logging half of your track day: you learn the line before the day and log what happened after each session. Lap times come from whatever times you — a transponder, a timing app, or the org's printout — and the notebook's stopwatch-style field makes punching them in quick.
Where does the track data come from?
Circuit geometry is derived from OpenStreetMap (© OpenStreetMap contributors, licensed ODbL). The reference line, corner guides and everything built on top are computed by Apex Lines from that geometry. Apex Lines is fully independent — no affiliation with any track, school, or series.
Does it need a connection at the track?
No. Everything — tracks, lines, guides, notebook — works fully offline. There's no account to sign into. iCloud sync between your devices happens automatically whenever you're back online.
What exactly is free?
The complete 38-circuit library with the computed reference line on the 2D map, prep checklists, your first track day in the notebook, and one bike's complete Garage ledger. Pro adds the 3D scene with fly-the-line, corner guides, an unlimited notebook, and unlimited bikes in the Garage — $4.99/month or $39.99/year.
Does the Garage know my bike?
It ships with a small starter set of common track bikes whose intervals were hand-transcribed from manufacturer maintenance schedules, each figure carrying its source and date. And the custom path is first-class, not a fallback: a nickname is the only required field, and every component can be renamed, moved between bikes, or retired. If your bike isn't listed, one tap files the make, model, and year as a request — the sheet shows exactly what's sent, and nothing else is.
Where do the Garage's service intervals come from?
Curated references with the receipts attached: every number cites its source ("Yamaha owner's schedule, street basis — track is harsher") with a link and the date it was last checked. A street figure is cited as context, never presented as governing track use; track-duty figures are labeled as derived, conservative references. You accept or edit each interval at setup — from then on the number is yours, and an interval you've edited is never rewritten by an update.
Is the Garage free?
Free keeps one bike's full ledger for good. Pro adds more bikes and accrues hours across your whole season. Nothing inside a bike is ever degraded on the free tier — the full ledger, cited intervals, readiness for your planned day, and export are all there — and archived bikes never count against the limit, so selling your bike doesn't paywall its replacement. Export is never gated.
Which devices does it run on?
iPhone (iOS 17 or later) and Mac (macOS 14 or later). It's one native SwiftUI app on both, and one subscription covers both.