Colle Del Lys

Colle Del Lys cycling climb profile

Colle Del Lys is listed as an HC climb in CH, and the numbers explain why before the road itself has to say much. The climb runs for 47.6 km from a start elevation of 287 m to a summit elevation of 2912 m, with a net elevation gain of 2625 m. The average gradient is 5.51%, but the key detail is the maximum gradient of 25.32%.

That combination matters. A 5.51% average over this much distance can look manageable on paper, but the length changes the physiology of the effort. This is not a climb to ride like a short threshold test. It is a long durability effort where the cost of early surges compounds. The maximum gradient also tells you the average is hiding real severity somewhere in the profile. Even if most of the climb feels rhythm-based, there is enough steepness in the data to punish overgearing and poor pacing.

How the gradient should be read

The supplied profile does not give sector-by-sector gradients, so the honest way to read Colle Del Lys is from the global shape: a very long net rise from 287 m to 2912 m, averaging 5.51%, with at least one section reaching 25.32%.

That means the climb should be approached as two problems at once. The first is duration. Over 47.6 km, small pacing errors become large fatigue costs. The second is variability. The 25.32% maximum gradient means you need to be ready for ramps that are far harder than the climb’s average suggests.

The practical takeaway is simple: do not pace the climb off the average gradient alone. If you ride the lower-gradient portions too hard because they feel comfortable, the steepest sections will force you above a sustainable effort. Once that happens, the rest of the climb becomes damage control rather than controlled climbing.

Pacing strategy

Start below the effort you think you can hold. On a climb this long, the opening target should feel almost too controlled. If you use /glossary/ftp as your anchor, this is a climb where staying disciplined under threshold early is more valuable than chasing speed.

The middle of the climb should be about preserving torque and cadence rather than forcing the pace. When the road steepens, let the gear absorb as much of the gradient change as possible before adding power. The maximum gradient is severe enough that some spikes may be unavoidable, but the goal is to keep them short and recover immediately once the road eases.

In the final portion, the elevation gain already accumulated becomes the main opponent. If you have paced correctly, this is where the steady 5.51% average starts working in your favour. If you have chased every ramp, the same average will feel much harder than it looks.

Gearing notes

Bring your easiest climbing setup. The 25.32% maximum gradient is the number that should drive gearing choice, not the 5.51% average. A gear that feels comfortable on a moderate alpine-style grade may become too heavy on the steepest ramps, especially late in a 47.6 km ascent.

The best setup is one that lets you stay seated and controlled on steep pitches without grinding yourself into fatigue. If you are unsure, gear lower than pride suggests. Colle Del Lys rewards patience, range, and a clean pacing plan more than aggression.