What is pacing complexity?
Pacing complexity measures how often and how sharply your required effort level changes across a course. It is not a measure of how hard a race is. A race can be brutally demanding yet score low on pacing complexity if the effort is distributed in long, consistent blocks where a single controlled pace works from start to finish.
High complexity means the course forces you to constantly shift between hard climbs, technical descents, and recovery sections in quick succession. These gear-changes are where poor pacing decisions compound: a runner who goes out too hard on an early climb has less time to recover before the next one. Low complexity means you can lock into a rhythm and hold it, even if that rhythm is extremely demanding.
How the score is built
Every race is scored 0-100 from seven weighted components, each drawn from the course's GPX and terrain data:
| Component | Weight | What it means |
|---|---|---|
| Gradient variability | 25% | How much the gradient fluctuates across the course in 0.5 km windows. High means the route never settles, constant switching between steep, moderate, and flat terrain kilometre after kilometre. |
| Gradient transitions | 20% | How often the course switches between materially different gradient bands per 10 km. High means constant gear-changes between climbing, flat, and descending sections in quick succession. |
| Gentle terrain coverage | 15% | How little of the course is at a manageable gradient (up to plus or minus 3%). High means very little flat or runnable terrain exists to allow rhythm recovery between demanding sections. |
| Final-third complexity | 10% | Whether the course remains demanding in its last third, when fatigue makes misjudgement most costly. High means gradient complexity does not ease off late in the race. |
| Technical terrain coverage | 5% | How much of the course is on trail, gravel, rocky, or other non-road surfaces. High means most of the race is on terrain where foot placement, traction, and energy cost are higher than road. |
| Terrain type changes | 10% | How frequently the surface type switches between road, gravel, soft trail, and technical terrain per 10 km. Frequent changes make it harder to settle into a rhythm, even when gradient is consistent. |
| Sustained effort burden | 15% | How long the pacing challenge must be held, based on the race's flat-equivalent energy cost. Longer means more scope for compounding errors across the full duration of the race. |
Rating scale
Compare against your own race history
On every race page, premium subscribers can see how that race's pacing complexity compares against their own previous races, so they know whether the pacing demands ahead are familiar or a step into new territory. Here is an example of what that comparison looks like:
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