Understand the shape of a course before race day. Upload a GPX to break it into its major climbs and descents — each with length, gain, average grade, and steepness — and find the crux. Everything stays in your browser.
Drop a course GPX here, or click to choose
Your file stays on your device.
A finish time is decided by a course's climbs — how many, how long, how steep, and where they fall. This tool reads a GPX and breaks the route into its major climbs and descents in the order you'll meet them, so you can plan effort, fuelling, and where to hold back. It works for any course: a race you found online, a rehearsal loop, or your own route.
The crux is the biggest climb by vertical gain — often the section that makes or breaks the day. The tool also flags the longest sustained climb and the steepest pitch, and labels every segment by average grade (gentle, moderate, steep, very steep, or extreme).
Once you know the crux, use the route comparison tool to check that your rehearsal route rehearses similar climbing, or the race pages to open the official course directly.
Your GPX is parsed entirely in your browser. Nothing is uploaded.
Upload the course GPX (or open this tool from a race page to load the official course). TrailSplits breaks it into its major climbs and descents in order, with length, gain, average grade, and a steepness class for each — plus the crux climb and an overall difficulty read.
The elevation profile is split at its peaks and valleys using a prominence threshold that scales with the total gain, so sustained climbs and descents are separated from GPS noise. Each climb reports its length, vertical gain, and average grade.
They come from the average grade of a segment: gentle (under 4%), moderate (4–8%), steep (8–12%), very steep (12–20%), and extreme (20%+).
The single biggest climb by vertical gain — usually the section that decides your race. The tool also flags the longest and steepest climbs.
Yes. It is free and your GPX is parsed entirely in your browser — nothing is uploaded to a server.