Milltir Cerrig

Overview

Milltir Cerrig is a Category 3 climb in Great Britain, running 5.6 km from a start elevation of 165 m to a summit of 474 m. On paper that is a net elevation gain of 309 m at an average gradient of 5.5% — a mid-length climb that most fit riders will file under "steady tempo effort" before they turn the pedals.

The paper version is misleading. Total ascent over the same 5.6 km is 645 m, more than double the net gain. That 336 m gap between what you climb and what you keep is the defining feature of this road: it undulates. You are repeatedly gaining height, giving some back, and gaining it again. For your legs, the effort scales with total ascent, not net gain, so budget accordingly.

How the Gradient Unfolds

The 5.5% average is an average of dips and ramps, not a constant wall. With 336 m of descent baked into the profile, long stretches sit well below 5.5% or point downhill, which means the climbing sections must be considerably steeper to make up the difference. The steepest ramp bites hardest at 18.49%.

Expect the profile to break down roughly like this:

• Flatter and false-flat recovery sections where the road gives height back
• Repeated short climbs that each demand a fresh surge rather than one long grind
• A steepest pitch of 18.49% that will force you out of the saddle or into your easiest gear

Pacing Notes

Do not chase an even speed here — the undulation makes constant speed impossible without wild power spikes on every ramp. Pace by even effort instead: hold a steady, sustainable power output and let your speed rise on the descents and dips, then fall on the climbs. Resist the urge to hammer over each short rise; those repeated efforts are exactly what blow riders up on a road like this.

If you do not know your ceiling, run the numbers through the FTP estimator first, then aim to sit just below that figure on the ramps and soft-pedal the recovery sections to bring your average back down.

Gearing

The 18.49% maximum gradient sets your gearing floor. A compact 34-tooth or sub-compact chainset paired with a wide-range cassette is the sensible choice — think 34×32 or 34×34 so you have a genuine bailout gear for the steepest pitch. On a punchy, undulating climb you will shift constantly, so a smooth wide-range setup matters more than raw top-end. Check your chainrings and cassette before the ride; you do not want to discover you are short a gear at 18%.

Summary

• Length: 5.6 km
• Average gradient: 5.5%
• Maximum gradient: 18.49%
• Net elevation gain: 309 m
• Total ascent: 645 m
• Category: 3

Milltir Cerrig is a climb that rewards riders who read the profile, not just the summit height. Pace it by effort, gear for the 18.49% ramp, and treat the 645 m of total ascent as the real workload.