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Trail Run: Pen y Fan Horseshoe

    Trail Running > Routes > Brecon Beacons > Pen y Fan Horsehoe

    Cribyn, Fan y Big and Craig y Fan from the summit of Pen y Fan
    Scaffolders at work on the summit of Pen y Fan
    The 'diving board' rock of Fan y Big
    View of Pen y Fan from the ascent of Cribyn

    A 20 km “snakes and ladders” tour of spectacular Brecon Beacons peaks including Pen y Fan — the highest point in South Wales.

    Distance: 20 km

    Ascent: 1,000 m

    Max. Altitude: 886 m

    Est. Time: 3.5 hrs

    Route Type: Circular

    Rating: –Hard–

    Route Verified: July 2025

    Why run this trail?

    According to the National Trust, around 750,000 people a year scale Pen y Fan, the highest point in the Brecon Beacons at 886 metres. As you’d expect, the main tracks are well defined, built like sandstone motorways and inevitably busy on a fine day. But the crowds soon disperse once you leave the summit and don’t detract from the experience. This route is popular for a reason: spectacular views open up wherever you pause for a breather.

    This is the classic horseshoe route – a climb to the ridge of Graig Fan Ddu from Taf Fechan Forest followed by a scalloped, clockwise loop of the summits of Corn Du, Pen y Fan, Cribyn and Fan y Big. It’s a bit of a staple and I met plenty of other runners tackling the same route – or slight variations of it – in both directions.

    Right up to the 11th hour I debated: should I ascend via Cefn Cwm Llwch or from Talybont Reservoir? There’s no shortage of options for a longer run here.

    After snatching just five hours sleep the night before, I was thankful I’d opted for this route and played it sensible. As it happened, it was a much tougher run than I expected, with plenty of hard running surfaces – a combination of engineered paths and the baked ground offered up after a long hot summer. I was yearning for wet feet and a bit of good old fashioned mud by the time this run was over.

    Taf Fechan Car Park to Craig Gwaun Taf

    Start of the Graig Fan Ddu Ridge with Taf Fechan Forest below
    The start of the ridge of Graig Fan Ddu, with Taf Fechan Forest in the valley below.

    I set off from the car park at Taf Fechan at 10 am on a beautiful July morning. The valley was still, the temperatures already in the low 20s. The first climb began promptly after crossing the Neuadd Dam – a sharp punt up to the ridge of Graig Fan Ddu, turning steep and rocky near the top.

    A quick detour south to the war memorial trig point didn’t last long as I was accosted by wasps and opted for a 50 m dash to shake them off. Back on track, it was simply a case of following the obvious ridgeline north towards Craig Gwaun Taf and the accompanying backdrop of mountains.

    View of Corn Du, Pen y Fan and Cribyn from the trail at Graig Fan Ddu
    Corn Du, Pen y Fan and Cribyn from the ridge of Graig Fan Ddu

    This section is a fairly undemanding 3.5 km of running across gently undulating terrain with great views from the ridge. So iconic are the peaks of Corn Du, Pen y Fan and Cribyn that I found it hard to peel my eyes away from them as they inched gradually nearer.

    Craig Gwaun Taf to Corn Du

    Dropping to Bwlch Duwynt, the foot traffic noticeably swelled as paths converged from the popular approach routes. A short, stiff jog and scramble later, I was on the craggy top of Corn Du (873 m), with expansive views over Cwm Llwch and the town of Brecon to the north.

    The steep sandstone 'ladder' up to Corn Du
    The steep sandstone ladder up to the summit of Corn Du.
    View of Llyn Cwm Llwch from the summit of Corn Du
    Looking down at Llyn Cwm Llwch from the top of Corn Du.

    Pen y Fan: The Summit Circus

    From Corn Du, the 500 m hop to Pen y Fan is foolproof – just follow the train of people headed to the summit!

    Two things grabbed my attention once I got there:

    1) About 30 very sturdy fellows in matching t-shirts were erecting scaffolding right by the summit cairn. A fundraising event, it turned out: they had carried every pole up from the valley. Possibly the next big thing in wacky outdoor pursuits. Gentlemen, I think you’re on to something…

    Scaffolders at work on the summit of Pen y Fan
    “Do us a favour, pop back down and get the big ladder for us would you mate?”

    2) The incredible views from the summit – particularly the south-east aspect, which showcases the peaks of Cribyn, Fan y Big and Waun Rydd as they snake away into the haze like breaking surf.

    Cribyn, Fan y Big and Craig y Fan from the summit of Pen y Fan
    Warning: mountains shown in this picture may not be to scale.

    Cribyn and Fan y Big

    It’s a steep and rocky descent on a hard packed trail from the summit of Pen y Fan en route to Cribyn (795 m) – an angular wedge of green felt that gets more imposing the closer you get. At this point, my feet were glad of the large, solitary pool of lukewarm water at the base of the climb.

    View of the track up to Cribyn from the descent of Pen y Fan
    The steep slog up to Cribyn with a very tempting wallowing pool at the bottom.

    There are very few switchback tracks in this series of peaks – the local way-marking forefathers must have been fairly direct in their philosophy. Cribyn is no exception. About half way up the climb, my head dropping and hands planted firmly on knees, I admitted defeat and switched to a power hike. The reward? Spotting the smallest lizard I have ever seen, who obliged me with a photograph.

    A tiny common lizard on the slopes of Cribyn
    I’m reasonably confident that this is an infant dragon.

    The crowds thinned on the climb up to Cribyn and the track grew less regimented. The summit offered great views back to Pen y Fan – a classic ‘crest of the wave’ view of this prominent mountain.

    View of Pen y Fan from the ascent of Cribyn
    Looking back: the classic ‘breaking wave’ of Pen y Fan, from the start of the climb to Cribyn.

    A fast, winding descent from Cribyn offered the welcome option of swapping rocky single track for patches of grass as the final summit of the day – Fan y Big – loomed into view ahead. The peak features distinctive tiers of rock banding the face of the mountain which are typical of the area.

    View of Fan y Big from the descent of Cribyn
    Fan y Big is up next and yes, it’s reasonably big.

    The climb to Fan y Big (719 m) is similar in length and gradient to Cribyn, but gifted with a few switchbacks from about the half-way point. The summit offered a cracking panorama of the entire ridge I had traversed. Naturally I just had to grab someone to take my photo on the famous ‘diving board’ rock which juts out over the escarpment. Shamelessly filed under mandatory clichés.

    The 'diving board' rock of Fan y Big
    “Just back a bit for me…” Behind, from left to right: Graig Fan Ddu ridge, Corn Du, Pen y Fan and Cribyn from the diving board at Fan y Big. This route is a beast.

    Fan y Big to Taf Fechan Car Park

    Shaking out tired legs and munching an energy bar, I struck out along the sandy single track of Craig Cwareli through the heather towards Waun Rydd. From this point, my route took me south on winding trails along the ridges of Graig Fan Las and Craig Fan Ddu, before finally dropping quickly down through the bracken and trees to Blaen y Glyn. There’s some great waterfalls here if you’re in need of a freshen up.

    Single track on Craig Cwareli with the town of Brecon in the background below
    Singletrack along the ridge of Craig Cwareli, with the town of Brecon just visible in the distance below.

    Distracted by a glimpse of the steam railway at the foot of Blaen y Glyn, I missed my turning for the short homeward section through Taf Fechan Forest. This provided an unwelcome sting in the tail – an additional 2 km of hot, thankless tarmac to reach my car.

    Not the ending I’d hoped for, but it didn’t dent the satisfaction of a superb morning in the mountains. Mission accomplished, it was tally-ho to my digs in Talybont for a spot of lunch and a gigantic ginger beer by the canal.

    Highlights

    Incredible views from the summits, ridges and everywhere else

    Clearly marked trails – it’s impossible to get lost in fair weather

    An up and down rollercoaster with some testing climbs

    Lots of runners to chew the fat with – it’s nice and social

    Men with scaffolding? Check listings beforehand to avoid disappointment

    Know before you go

    The paths and summits of Corn Du and Pen y Fan are busy

    Major trails are engineered for conservation and can be heavy going

    Some of the descents are steep and rocky and require careful footing


    Have you run this route? If you’ve discovered a better variation, noticed something that’s changed or have local knowledge to share, I’d love to hear from you.

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    Dean

    About the author
    Dean is a qualified Strength & Conditioning Coach, Personal Trainer and full-time fitness enthusiast in Godalming, UK



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