The hardest hill climb in the United Kingdom.

Cycling The Cowlyd, Wales

Ride two miles gaining 1,329’ at 12.5% average grade. 😓

WOW - enough said!  This climb is simply a monster with several stretches in the red zone - above 16%, including one massive stretch at 20% for 200 yards.  This climb is ranked #1 UK and Wales on PJAMM’s FIETS formula-based difficulty index, as well as the UK Top Hardest Climbs list provided to us by Simon Warren before our second trip to document the UK’s top climbs in 2022 -- thus, it’s The Real Deal!

The name of this climb comes from Llyn Cowlyd, the deepest lake in northern Wales.  If we continue (downhill!) 1.6 miles we come to the Llyn Cowlyd Dam, and if we continue for two miles, we’ll hit Llyn Cowlyd Reservoir.  The original dam was completed in 1897 and the current dam in 1922.  This astounding bike climb is in the northeastern section of Snowdonia National Park, Wales’ first National Park (est. 1951).

Climb start.

Climb summary by PJAMM Cycling’s Brad Butterfield.

The Cowlyd starts in a very scenic little village called Trefriw. Here there are a few nice looking hotels and restaurants, but not much else. Beneath the old bridge stands a WWI and WWII memorial. Our climb brings us quickly to the farmlands that surround the village.

For the opening miles, you’ll be surrounded by thick vegetation, validating the annual rainfall statistics in the area. A series of tight turns and painfully steep inclines brings you above the treeline, and there you have views of the idyllic Welsh countryside.

This top Welsh bike climb is true to form as it is basically steep the entire way. You will pass a heavily wooded area and about a mile up the surroundings open up to an amazing view of the valley and a lake in the distance. Though there are many sheep (well, that’s Wales, and we LOVE IT!) they seem trained to get the heck out of the way and the road itself is pretty clean (i.e. generally free of sheep ___).

The top sections of our route roll between sections of 10% to 15%.  On this climb, the 10% portions come as a relief of all things. The finish point is at a cattle guard, but your blessed ending to this cruel climb is otherwise unmarked.

The descent has some tight turns, so be careful going down, especially if it is wet. I would add this climb to Melin y Coed to make it a route versus stand-alone climb, as it is only a couple of miles away and you can take a cool bridge to the other climb. Overall this is a great, steep workout climb and takes you to a really beautiful open view.

That’s a wrap!