How Skibuddy measures.

1. The recording

Skibuddy records GPS position, elevation from the phone's barometer, heart rate from a paired Bluetooth strap and the phone's motion sensors at 50 readings per second. Skibuddy saves the trace with the session.

The phone computes laps and the live metrics during the session. Skibuddy's server finds routes, climbs and checkpoint splits in the saved trace and matches them again whenever you save or edit a finished session.

2. Lap gates

The gate is the first position after Start with an accuracy better than 30 meters, facing the direction you set off in. Skibuddy can close a lap once you have skied at least 50 meters from the gate and 400 meters in total, and closes it when you pass back through the 30 meter gate heading within 60 degrees of the start direction. An out-and-back comes back facing the other way, so Skibuddy never laps it.

For stadium sprints, Short Loop Mode lowers those limits to 15 and 50 meters. Set a new gate mid-session and Skibuddy moves it to where you stand, takes your current heading and closes the running lap. Press the lap button to close a lap by hand at any time.

3. Routes

Skibuddy turns a finished session of at least 1 kilometer and 60 recorded points into a route when none of your existing routes matched it. A later session matches a route when it enters the route's start gate within 30 meters, heading within 60 degrees of the route's direction, passes its checkpoints within 60 meters and reaches the end. Skibuddy adds each match to the route's history with its time, pace, heart rate and snow.

A personal best is your fastest match on a route.

4. Climbs and checkpoints

After each session Skibuddy smooths the elevation over five points and finds sustained ascents of at least 25 meters of gain, an average grade of 4% and a length of 150 meters. Skibuddy merges rises separated by less than 30 meters of descent into one climb, treats two climbs as the same climb when both ends lie within 45 meters and counts each pass as a rep. When the server finds no climb, the phone looks for climbs of 20 meters or more within each lap.

You place checkpoints on a finished session. Skibuddy splits every later session that passes within a checkpoint's gate and shows the time in the lap's sectors and splits.

5. Stride rate, glide and balance

Skibuddy reads the phone's motion sensors 50 times a second, analyzes them in three-second windows, separates vertical from horizontal movement and finds your forward and sideways axes from the data, so the phone needs no fixed orientation in the pocket.

Stride rate is the number of stroke cycles per minute on the forward axis. Glide is your speed divided by cycles per second: the meters you travel with each cycle. Balance is the share of sideways movement to the left. Skibuddy counts glide only above 0.5 meters per second and 10 cycles per minute, and switches balance off in a pants pocket.

6. Technique

You declare classic, skate or mixed at the start. Within that, Skibuddy names the technique from rules over speed, grade, sideways sway, vertical bounce and stride rate. Skibuddy calls anything faster than 20 km/h on a downhill of 2% or more the tuck. It reads strong sideways sway as skating: V1 on grades above 4.5%, V2 above 45 cycles per minute, otherwise V2 alternate. Without that sway, Skibuddy applies the classic rules: diagonal stride on grades above 3% with a clear bounce, herringbone on grades above 8%, otherwise double poling.

A technique has to hold for two consecutive seconds before Skibuddy switches to it. These rules are the first version. Skibuddy doesn't publish an accuracy figure yet; the first-snow cohort measures one on real trails.

7. Technique cues

With technique cues on, Skibuddy averages your left/right balance over the last 20 seconds while you climb a grade above 3%. When that average leaves 45 to 55%, Skibuddy says out loud which side you lean to, after any lap announcement, then stays quiet for at least 90 seconds and until balance comes back inside the window. It never cues in a pants pocket, while auto-paused or while you aren't striding.

8. Snow and the Smart Coach

When you save a session, you give it one of eight snow conditions: Fresh Powder, Packed Powder, Groomed / Hard, Icy / Glazed, Corn / Spring, Slush, Man-made / Artificial or Thin Cover.

The Smart Coach looks at your last 20 sessions and shows the first rule that applies: a pants-pocket session, a balance outside 45 to 55%, glide 10% above or below your average for the same technique (with at least three earlier sessions in it), or a stride rate 15% above your average. When glide runs well above or below average on groomed or packed snow, it suggests icy or slushy snow for the session.

9. Heart rate

Skibuddy connects to any Bluetooth strap that uses the standard heart-rate profile. Skibuddy sets the zones from your maximum heart rate: the value in your profile, otherwise 220 minus your age (at least 150), otherwise 190. Recovery is below 60%, Endurance 60 to 70%, Tempo 70 to 80%, Threshold 80 to 90% and VO2 Max from 90%.

10. The wax room

Skibuddy ranks a setup (skis, glide wax and, for classic, kick wax) by its glide index: for every session skied on that setup, the session's average glide per stroke cycle divided by your average glide for the same technique across all your sessions, then averaged. An index of 1.08 means the setup glided 8% better than your own average. You filter by snow condition and technique, and every row shows how many sessions it rests on.

11. What Skibuddy leaves out

Skibuddy doesn't adjust times for the snow, doesn't compute a training-load score and doesn't use machine learning yet. It shows the snow and the technique next to the time, and leaves the judgment to you and your coach.

12. Verification

Skibuddy's replay suite runs synthetic loop sessions with modeled GPS noise through the lap engine: four laps of 3.63 km, and a mixed session of 3.63, 3.63, 5.42, 5.42 and 7.43 km under two noise levels. Every loop has to close as its own lap within 5% of its length, and a 4 km out-and-back has to produce no laps.

Synthetic traces prove the logic, not the snow. The first-snow cohort records real sessions to measure both on actual trails.