Method
TripRace Difficulty Score
The difficulty score is course and conditions only. It does not care how fast the field is. The PR score is a different question: where a fast clock, or a Boston qualifier, is more plausible. Both run from 0 to 100. Both stay blank when too few inputs exist.
Difficulty
D = 0.30 G + 0.15 A + 0.25 H + 0.10 W + 0.10 C + 0.10 S. Each letter is already on a 0–100 scale. If a letter is missing, we drop its weight and rescale the rest. We publish D only when the weights we still have add up to at least 0.40. Surface alone is not enough.
- G, gain: metres of climb per kilometre, divided by 30, times 100, then capped. We skip G when the stored gain is marked uncertain.
- A, altitude: 0 below 300 m, then a straight line to 100 at 2,000 m. Start elevation is the first sample of a verified course file, or else the Open-Meteo grid elevation at the start coordinate.
- H, heat: the harsher of the dew-point band and the high-temperature band. Dew point at or below 5°C scores 10, 6–10 scores 30, 11–15 scores 50, 16–20 scores 75, and above 20 scores 95. Highs use 12, 16, 20, and 24°C as the same steps.
- W, wind: median wind under 3 m/s scores 15, under 5 scores 40, under 8 scores 70, and 8 or more scores 100.
- C, cutoff: a 5:00 marathon scores 100 and a 7:00 marathon scores 0, with a straight line between. Other distances scale those clocks by distance / 42.195. No cited limit means C is left out, not treated as easy.
- S, surface: road 15, mixed 45, gravel 70, trail 90.
A net downhill of more than 1 m/km would multiply D by 0.92, and only after a cited course certificate. We do not have that certificate field yet, so the factor is off for every race.
PR and BQ friendliness
P = 0.45 F + 0.25 T + 0.20 B + 0.10 E, with the same drop-and-rescale rule. We publish P only when the remaining weights add up to at least 0.45.
- F, flatness: 100 minus gain per kilometre / 20 times 100. No bonus for net drop until a certificate is cited.
- T, cool temperatures: 100 minus H.
- B, BQ evidence: a published BQ rate, 0% mapping to 0 and 30% or more mapping to 100. No citation, no B. The rate is the measured edition on the source page, not a forecast.
- E, execution: a cited cutoff of 6:30 or looser on a marathon scores 50, 6:00 to 6:30 scores 30, and a tighter clock scores 10, scaled for other distances. Pacers and certificates are not in the formula yet.
Bands on the PR score: 70 and above is fast, 40 to 69 is mixed, and under 40 is hard. Weather medians use Open-Meteo, 2011 through 2025, on the race's month and day plus or minus 7 days. A wet day in that set is at least 1 mm of precipitation.