Explore how a synthetic elevation profile changes a pace estimate. Enter a goal time and choose a legacy course or supply elevation totals. GAP is an estimate; current-fitness guidance requires a recent race.

How the adjustment works

Grade-Adjusted Pace (GAP) answers one question: if you'd spent the same energy running on flat ground, how fast would that pace have been? It uses the metabolic cost-of-running curve measured by Minetti et al. (2002), where the energy per metre at gradient i is C(i) = 155.4·i⁵ − 30.4·i⁴ − 43.3·i³ + 46.3·i² + 19.5·i + 3.6 J/kg/m. Each named course uses a synthetic profile. The model integrates cost across those reconstructed segments; their count does not establish measurement accuracy. Dividing raw pace by the resulting effort factor gives your GAP.

How the profiles are built

Profiles combine inherited control heights with seeded synthetic undulations. Ascent is a reconstruction target, not a verified measurement. Min/max and the positions of climbs are model outputs; no coordinates or GPX geometry are available. A synthetic profile can support an explicitly labelled GAP estimate, but cannot verify a hill, turn, surface or race-day pacing recommendation.

Data quality and versions

All 59 named routes retain their legacy inputs, with a separate event, unverified edition listing, route version and repository source. Legacy organizer links and dates have not been rechecked. Geometry is missing; elevation is estimated. Route-specific training is withheld until its required measured features are verified. Current-fitness guidance needs a recent race. GAP and difficulty remain model estimates, not race predictions or physiological validation.