Col de Loung Phai

Col de Loung Phai cycling climb profile

The Col de Loung Phai is not a long Alpine-style grind, but the numbers say it deserves respect. At 8.2 km with an average gradient of 4.15%, it sits in that awkward middle ground where the climb can feel manageable if ridden steadily, but costly if the steeper ramps are attacked too early.

The climb starts at 166 m and tops out at 505 m, giving a net elevation gain of 339 m. That vertical gain spread across the full distance explains the relatively moderate average. The key detail is the maximum gradient of 9.67%. A climb averaging just over 4% but touching nearly 10% is unlikely to feel completely uniform. The rider has to be ready for changes in resistance rather than settling into one fixed rhythm from bottom to summit.

As a category 3 climb, the Col de Loung Phai is best treated as a sustained aerobic effort with several harder moments layered into it. The mistake is to look only at the average gradient and assume it can be ridden like a false flat. The max gradient makes the pacing problem clear: if you ride the early slopes too close to threshold, the sharper sections can push you over the top of your sustainable range and force a costly recovery.

How to pace it

Start controlled. For most riders, the right approach is to hold something around upper endurance to tempo on the easier ground, then let effort rise naturally on the steeper pitches without chasing speed. If riding by power, avoid treating the opening kilometres as a place to prove form. Save the sharper efforts for the sections that demand them.

The practical target is a smooth climb rather than a fast-looking start. On a climb of 8.2 km, over-pacing the first half rarely saves time. It usually just turns the upper half into damage control. Use your /glossary/ftp as a ceiling, not a target, unless the climb is being ridden as a focused threshold effort.

Gearing and riding feel

Because the maximum gradient reaches 9.67%, gearing matters more than the average suggests. A setup that feels fine on 4% gradients may become inefficient once the road pitches up. Choose a gear that lets you keep pressure on the pedals without grinding when the slope steepens.

The best rhythm is seated, steady, and responsive. Shift before the ramps bite, keep cadence from collapsing, and accept that speed will fluctuate. The climb rewards riders who manage torque and effort cleanly, not those who try to force one pace across changing gradients.

If using the Col de Loung Phai as a training climb, it works well for controlled tempo work or a threshold-focused test when paced correctly. For estimating sustainable targets before riding it hard, a tool like /tools/ftp-estimator can help set realistic expectations.