Pen-y-Pass

Overview

Pen-y-Pass is a category 3 climb in Great Britain, running 3.6 km from a start elevation of 166 m to a summit at 371 m. That gives a net elevation gain of 205 m and an average gradient of 5.67% — a moderate climb on paper, long enough to matter but short enough to attack if you know the road.

The number that reshapes that picture is the total ascent: 303 m against a net gain of only 205 m. That 98 m gap means the road does not climb cleanly. Somewhere on those 3.6 km you give back close to 100 m and have to earn it again. Undulation like this taxes riders who pace to a single steady figure, because every dip breaks rhythm and every re-climb forces a fresh surge.

How the Gradient Unfolds

The 5.67% average is an accounting trick here. With 303 m of total ascent packed into a net-205 m climb, the real road alternates between harder ramps and stretches that flatten or drop away. The steepest pitch touches 14.41% — roughly two and a half times the average — so treating this as a uniform 5.67% grind will leave you overgeared and out of rhythm at the worst moment.

Expect the profile to look like this:

• Flatter or descending sections that let you recover but also bleed the elevation you have to reclaim
• Repeated short climbs rather than one continuous wall
• A single steepest ramp near 14.41% that demands your lowest gear

Pacing Notes

On a smooth climb you could ride even-effort and let speed vary. Pen-y-Pass rewards the opposite discipline: hold your sustainable power output through the ramps, and deliberately ease — do not coast hard — through the flatter and descending sections so you carry momentum into the next rise. Even-speed pacing is a trap on undulating roads; it forces you far over threshold on the 14.41% ramp and lets you loaf where the grade drops.

If you do not know your threshold number, set a realistic target with the FTP estimator before you plan the effort. Cap your surges on the steep pitch at a few percent above threshold, and reset your breathing on every recovery stretch.

Gearing

Gearing is dictated by the steepest gradient, not the average. At 14.41%, you want a compact or sub-compact chainset paired with a wide-range cassette — a 34×32 at minimum, and 34×34 if you spin rather than grind or you will be climbing on tired legs. That low gear lets you keep cadence on the steep ramp instead of stalling and mashing. Check your setup before the ride: confirm your smallest chainring and largest sprocket, and make sure the rear derailleur actually shifts cleanly into that bottom cog under load.

Summary

• Length: 3.6 km
• Average gradient: 5.67%
• Maximum gradient: 14.41%
• Net elevation gain: 205 m
• Total ascent: 303 m
• Category: 3

Pen-y-Pass is short but deceptive: a category 3 climb whose 98 m of extra ascent over its net gain make undulation, not raw length, the real challenge. Pace the ramps, protect your rhythm through the dips, and bring a low enough gear for that 14.41% pitch.