Babusar Pass

Overview

Babusar Pass is one of those climbs whose numbers alone tell you it belongs in a category of its own. Over 35.7 km the road rises from 1134 m at the base to a summit of 4163 m — a net elevation gain of 3029 m at a relentless average of 8.48%. That combination of extreme length and a genuinely steep mean gradient is why it carries the HC (hors catégorie) rating, the hardest grade on the scale that runs down through category 1, 2, 3, and 4. This is not a climb you dip into; it is a full day's effort compressed into a single ascent.

How the Gradient Unfolds

The headline figure is 8.48%, but averages hide the story. With a maximum pitch of 14.9%, the steepest ramps sit more than six points above the mean, meaning long stretches must run gentler to balance them out. Expect the climb to oscillate: sustained sections around and above the 8.48% average, punctuated by sharper kicks that spike toward 14.9%, and occasional shallower reliefs where you can briefly recover cadence. The total ascent of 3009 m tracks closely with the 3029 m net gain, which tells you this is an almost continuously upward road — there is very little descending or false-flat rolling to give the legs a true break across the full 35.7 km.

Pacing Notes

On a climb this long, discipline in the first third decides everything. The single biggest mistake is treating early ramps like the whole climb is 8.48% — it isn't, and the 14.9% pitches later will punish anyone who overspent. Anchor your effort to your FTP and aim to sit comfortably below threshold for the bulk of the 35.7 km, saving headroom for the steep sections. If you are unsure of your current numbers, run them through the FTP estimator before you commit to a target. With 3029 m to gain, hours on the road are guaranteed, so pace by feel and power rather than ego, and treat the shallower reliefs as active recovery, not opportunities to attack.

Gearing

Gear for the 14.9% maximum, not the 8.48% average — the steep pitches are where an underspec'd cassette forces you to grind at unsustainable torque. A compact chainset paired with a wide-range cassette is the sensible baseline here. A 34×32 low gear will get most fit riders over the summit, but given the 35.7 km length and 3029 m of gain, the fatigue late in the climb makes a 34×34 the wiser choice for anyone who values spinning over grinding. On a 4163 m summit, the ability to keep a smooth cadence deep into the effort matters more than saving a few grams.

Summary

Babusar Pass is a true HC test: 35.7 km, 3029 m of net elevation, and pitches up to 14.9% that demand respect from the base. Pace conservatively, gear generously, and let the 8.48% average remind you that consistency, not heroics, gets you to the top.

Length: 35.7 km
Average gradient: 8.48%
Max gradient: 14.9%
Start: 1134 m
Summit: 4163 m
Net gain: 3029 m
Total ascent: 3009 m
Category: HC