Afon Ddu Bike Climb - PJAMM Cycling

3.2
FIETS
0.4 mi
DISTANCE
465 ft
GAINED
23.4 %
AVG. GRADE

FULL CLIMB STATS

INTRO

This is Simon Warren's pick for hardest climb in Wales and rightly so!  This climb is ranked #6 Wales on the Fiets Index - regardless of its rank, it is an absolute brute. 

Visit our Top UK and also our Top Wales hill climbs pages for photos, summaries and statistics for their respective top hill climbs. 

See more details and tools regarding this climb's grade via our interactive Profile Tool.
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CLIMB SUMMARY

narrow, forest debris covered road that looks more like a trail

Cycling the indomitable Afon Ddu, Wales

Ride only 600 meters but at a stunning 21.3% average grade.

Simon Warren (100 Greatest Cycling Climbs, UK) ranks this as the hardest climb in Wales and he will get no argument from us on that front! This climb comes with the steepest 500 meters in all of the UK at 25%, and it comes at the beginning of the climb so be prepared to strain at the outset.

photo collage shows 25% grade on rough roadway

The climb is named after the stream that flows near it and originates well up the mountain at Llyn Cowlyd Reservoir.

Climb summary by PJAMM Cycling’s Brad Butterfield:

Afon Du is forever burned into my muscle memory. This is a climb so steep and treacherous that making it to the summit is not guaranteed. Obviously excellent fitness is required, but so is low gearing. I used a 34x42 and never once even considered dropping down into a harder gear. This climb will have your legs in flames and your lungs begging for mercy. For the adventurous and brave, there is no better destination in Wales than Afon Du. Bring your best.

bike parked at climb start next to sign that reads "The Flow of this River Can Change Without Warning"

Climb start.

In his Cycling Weekly article about this beast, Simon Warren refers to the Afon Ddu climb  as “Baby Zoncolan.”  This is an informative and entertaining article about Afon Ddu by Simon:

“‘There’s always a bigger fish.’ That’s what the ancient proverb says, and just when I thought I’d ridden the steepest road in Britain, and put the matter of determining the country's toughest cycling climb to bed once and for all, up popped another hideous incline to further move the goalposts and redefine suffering. . .” (Britain's Baby Zoncolan).

Photo collage shows informational signs and grate in roadway 

This climb is steep beyond belief with a full 100 yards in the middle averaging 25%.  

forest debris covered roadway, switchbacks

traction grooves etched into cement roadway, steep segment of road

You know you are in for it when the road surface is cement with traction grooves etched into it.

For your road bike, bring low pressure and at least 28mm tires and a 34/42 and end at the gate.  However, if you have a mountain bike, you can keep going to enjoy the trail, but be on the lookout for sheep. No matter what, you're going to want to make sure those brakes work well and with anything other than hydraulic disc brakes you're going to want to check those pads after.  This is one of those climbs where it is very difficult to maintain braking traction on the descent.

climb finish at gate

Thank you gate!

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