Trail runners, this is not your average event.

The Tenacious Ten by Limitless Trails returns for 2026 with a new mountain, a new format and a serious test of endurance, set on the slopes of Mynydd Troed in the Black Mountains, within Bannau Brycheiniog (Brecon Beacons) National Park.

After previous editions on Table Mountain and Pen Cerrig-calch, this move marks a bold next step — and one that raises the challenge.

Built by Runners, Shaped by the Landscape

Limitless Trails have built a strong reputation for creating events that are designed by runners, for runners — combining thoughtful course design with a genuine understanding of the terrain and the people taking part.

Their events are rooted in the landscapes they operate in, working with the character of the mountains rather than against them. The move to Mynydd Troed reflects that approach — a route that is both demanding and rewarding, offering runners a true sense of place.

It’s not just about putting on a race. It’s about creating an experience that respects the environment, challenges participants and keeps them coming back.

A New Mountain, A New Challenge

Mynydd Troed delivers exactly that.

Starting from the base, runners face a steep, unrelenting climb, with several false summits before reaching the top. The reward is a set of sweeping 360-degree views across:

• The Black Mountains
• The central Brecon Beacons
• Llangorse Lake below

From there, the route shifts quickly — with technical descents, steep drops and more runnable open sections, demanding both control and confidence.

10 Hours. As Many Loops As You Can Take.

At the heart of the Tenacious Ten is its 10-hour endurance format, built around a 3.2-mile loop with approximately:

• ⛰ 1,036 ft ascent per lap
• ⛰ 1,064 ft descent per lap

The aim is simple:
Complete as many laps as possible before the final horn.

• A strict 10-hour cut-off applies
• Any lap not completed before the horn does not count
• The pressure builds as the clock runs down

New for 2026, runners can also choose their direction after the first lap, adding a tactical element to how the race unfolds.

Solo or Team – A Flexible Challenge

The event is open to:

• Solo runners
• Pairs
• Teams of four

Team entries are based on a combined lap total, creating a “last one standing” feel that rewards consistency, resilience and teamwork.

Properly Supported, Properly Tough

This is a demanding course — but it’s well supported:

• Fully marked route
• Clip stations at the trig point and base
• A well-stocked refuel zone at HQ
• Drop bag access throughout the day

Expect everything from energy snacks to homemade cake waiting at the base — small details that make a big difference over 10 hours.

A True Test in the Brecon Beacons

The Tenacious Ten is designed for runners who want more than just distance. It’s about:

• Endurance
• Decision-making
• Mental strength
• Respect for the terrain

With a new course comes a new benchmark.

A new course record is waiting.

Plan Your Entry

📍 Mynydd Troed, Black Mountains
⏱ 10-hour endurance format
👟 Solo, pairs or teams

Find out more and enter via Limitless Trails.