How do you time an MTB downhill run with your phone, without chips or timing gates?

Updated: 13 November 2026

A phone can time a downhill run if the app knows exactly where the trail starts and finishes. In No Last Run the start and finish are virtual lines on the map. GPS logs your position about once a second, and your time is the gap between crossing the start line and crossing the finish line. No chip, no photocell, no friend with a stopwatch at the bottom. You need a trail that has a start and finish in the app, and a phone in your pocket.

How it works, step by step

1. Pick a bike park and a trail, then a mode: ranked run or practice.
2. On the readiness screen the app warms up GPS and shows how far you are from the start line. When the signal is good, the indicator turns green.
3. Tap the screen to arm the run and put the phone away. The timer starts by itself when you cross the start line heading downhill.
4. Ride. Don’t touch the phone until the finish.
5. The timer stops by itself when you ride through the finish line. On a ranked run you don’t stop it by hand.
6. The result screen shows your time, the verification status and your position on the trail’s board.

Time is never measured from a “start” tap to a “stop” tap. Only the line crossings count, worked out from GPS points.

How the app knows you rode the whole trail

A time alone isn’t enough: someone could cut a corner or start lower down. So a ranked run is verified before it reaches the board. It has to start at the start gate, pass the checkpoints along the trail, follow the trail’s line without shortcuts, finish at the finish gate and keep a strong enough GPS signal.

The app also flags the impossible: position jumps of hundreds of metres, speeds no bike reaches, riding the wrong way. Finally the server works out the start and finish crossings from the recorded GPS points on its own. A run without both crossings doesn’t count. The full rules: How the gravity league works.

How accurate phone timing is

Honestly: less accurate than a race chip. Phone GPS is usually off by a few metres, more under dense trees. A position fix arrives about once a second, so the app works out the crossing moment between two fixes. With a weak signal a run may fail verification.

For a league that’s enough, because everyone rides the same trail between the same gates, timed the same way. For official race results decided by hundredths of a second you still need chip or photocell timing. The terms say it plainly: the app doesn’t guarantee 100% accurate timing.

Getting your phone ready

• “Always” location permission. A ranked run records in the background, with the phone in your pocket and the screen off. Without it you can only ride practice.
• Start in the open. Wait for the readiness indicator to turn green. Dense forest weakens the signal.
• Phone in your pocket. Ideally one that zips. Don’t hold it or look at it while riding.
• Ride it out. Don’t stop before the finish. Ride through the line and the timer stops itself.
• No signal is fine. The run is saved on the phone and sent once you are back online.

Other ways to time a run

• A stopwatch and a friend at the finish. Free and instant, but someone stands at the bottom instead of riding, reaction time is part of every result and nothing is saved.
• Races with chips or photocells. The most accurate timing and an official result, but only on race day, with entries and fees.
• A GPS watch or bike computer. Records the whole track and your speed, but you set the start and finish yourself and comparing with others means swapping files.
• Training apps with segments. Handy if you record every ride anyway. Segment times are worked out afterwards from the recorded track, so the result depends on how well the track hit the segment’s start and end.

Full comparison: How to race bike park trails outside of races.

Who it isn’t for

• If you need an official race result or guaranteed timing to the hundredth, use chip timing.
• If you ride a different line every time, with no fixed start and finish, there’s nothing to compare. The league works on trails with a fixed course.
• If you don’t want to give the app background location, you are left with practice, which never counts for the ranking.

How to start

1. Get No Last Run from the App Store or Google Play. It’s free.
2. Create an account with your email address and a one-time code.
3. Pick a bike park and a trail. If it isn’t there, add it and record the first run.
4. Ride practice first to learn the trail, then go ranked.

Read next

• How does the No Last Run gravity league work?Season, trail leaderboards, the podium, ranked runs vs practice, verification, Pioneers and fair play.
• How can you race bike park trails outside of organised races?Options compared: stopwatch, GPS watch, segments, fixed timing at the park, amateur races and a league app.
• How do you add a bike park and a trail to No Last Run?A bike park and a trail step by step: submitting the place, the Pioneer’s first run, trail statuses and what is public.

No Last Run: home page and common questions