Brown Family Sports · Course data
Edmonton 2026 Full Marathon
Certified distance 42.195 km. Runners reported their
watches reading long; the organisers say the course was measured and certified, and the results
stand. We are collecting GPS tracks to see what the data actually says.
Ran the half instead? →
Read this before you decide what your watch proved.
GPS over-measures. On a perfectly certified course almost everyone's watch reads long — typically
0.5–1.5% over, and worse among downtown towers, which is exactly where this course
runs. A certified course is also measured along the shortest possible route, so unless you
ran every tangent perfectly you covered more ground than the certificate claims. A single
long watch reading is not evidence of anything. What can be evidence is a large sample:
the distribution of hundreds of tracks, how far it sits from the 0.5–1.5% you would expect anyway,
and whether the recorded route matches the certified map turn for turn. That is why we want your
file rather than your screenshot.
Your file never leaves your device as a file
How this works. Your browser opens the GPX and pulls out the
numbers — latitude, longitude, elevation, timestamps. Those numbers are what we receive. We never
run an XML parser on our server, which is the thing that makes accepting GPX files dangerous in the
first place. If you tick the archive box we also keep the original bytes, unopened and never served
to anyone, purely so the provenance of a finding can be checked later.
One privacy thing worth your attention. If you started
recording at home or in the hotel, your track begins at your front door and we would be storing
that. Crop the file to the race in your watch app first if that matters to you. Bib and contact are
optional — leave them blank and the submission is anonymous.
What we do with it
- Measure each track against the certified 42.195 km, raw and noise-filtered.
- Publish the distribution — median, spread, sample size — not cherry-picked outliers.
- Compare recorded routes against the certified map to see whether the shape, not just the
total, differs.
- Publish the method alongside the result so anyone can disagree with it on the merits.