How to find the fastest part of a hike from a GPX file

The short answer

Walk through the track's points in order, and instead of computing one pace for the whole hike, compute it for a lot of short, overlapping stretches — every 100 to 200 metres of distance covered, say, rather than every single point-to-point step. For each stretch, take the distance covered and divide it by the time it took, exactly as you would for the whole hike. The stretch with the best pace is the fastest part of the route, and the distance and time figures behind it are already sitting in the file — nothing about a standard GPX track needs to be recorded specially for this to work.

Why one average pace can never answer this

Average pace divides total distance by total moving time, which by construction treats every stretch of the hike as though it moved at the same steady rate. A hike that starts on a slow, rocky climb, opens onto a flat stretch near the end, and finishes with an easy stroll back to the car can average out to a modest, entirely honest pace for the whole thing, while that flat stretch on its own, taken over a couple of hundred metres, might run close to twice as fast. The average is not lying — it is answering a different question than "where was I moving fastest," and no amount of staring at one number pulled from the whole route is going to answer the second question instead.

Splitting a hike into per-kilometre or per-mile splits runs into a milder version of the same problem. A short, genuinely fast stretch sitting inside an otherwise ordinary kilometre still gets blended with the rest of that kilometre, just over a smaller stretch than the whole hike. Finding the fastest part specifically means working in a unit short enough that a real burst of speed cannot hide inside it.

What a GPX file already has for this

A GPX track is a plain ordered list of points, each one a latitude, a longitude, and usually a timestamp. That is the same raw material behind every derived number a hike report shows — total distance, moving time, average pace, elevation gain — all of them calculated fresh from the same list rather than stored in the file as numbers of their own. Pace over a short stretch of the route is one more thing that list can be turned into, using nothing that is not already there: the distance and time between a handful of consecutive points is enough.

The wrinkle: point-to-point speed is too noisy to use directly

Position is never recorded with perfect precision, and a single point-to-point distance can be off by a few metres purely from that ordinary jitter, with no real extra movement behind it at all. Do this calculation between only two consecutive points — often just a few metres apart, logged a few seconds apart — and an ordinary walking stretch can occasionally produce a pace reading well ahead of anything realistically walked, purely because one point happened to land a couple of metres off to one side and the next landed a couple of metres off to the other. That single bogus stretch would win "fastest part of the hike" over every real fast stretch in the file if it were left in.

Widening the stretch to a fixed distance — 100 to 200 metres is usually enough — fixes this, because it divides a genuine distance covered over enough time that a few metres of position error on either end barely moves the result, while a real fast stretch that runs for a couple of hundred metres or more still shows up clearly. Too narrow a window and noise wins; too wide a window and a short burst of speed gets blended back into the more ordinary pace around it, the same dilution that per-kilometre splits already have. Somewhere in between is where a real, short fast stretch is both visible and trustworthy.

Working through it, with real numbers

Say a track logs a point roughly every five seconds. One 150-metre stretch takes 110 seconds to cover — a pace of about 12 minutes 13 seconds per kilometre. The very next 150-metre stretch takes only 75 seconds — a pace of about 8 minutes 20 seconds per kilometre, noticeably quicker. Move on again and the following stretch takes 130 seconds, back down to roughly 14 minutes 27 seconds per kilometre. The middle stretch is the fastest part of this route, and it would have been sitting silently inside a single average pace of somewhere around 11 or 12 minutes per kilometre for the whole hike if nobody had gone looking at anything shorter than the total.

Where TrailCam fits in

TrailCam reports one average pace for the whole hike rather than a stretch-by-stretch curve, so a short fast stretch sits inside that single number the same way it would in any average. For anyone who wants to find exactly where that was, a route exports as GPX 1.1 or CSV with every recorded point intact, which is exactly the raw material this method needs. Export is part of the optional TrailCam Pro upgrade; the app itself is free to download.