GranDiagonal

How rough the surface is. Based on what you're actually riding on — smooth road, gravel, technical off-road, or snow. If a race mixes surfaces, we score it by the toughest one present, not an average.

How much elevation you'll be grinding through. We look at this two ways: how steep the climbing is per kilometer, and how much total elevation you'll gain over the whole race. Whichever one is worse is what sets the score — so a short brutal climb and a long race with a massive total climb can both score high, for different reasons.

How hot conditions are likely to be. Based on where the race is and what time of year it runs — a race near the equator will always run warmer than one near the Arctic Circle, even in each region's own hottest month.

A single big-picture tier combining total distance and total climbing, so you get one quick read on how the race stacks up overall.