Brechfa Forest – Byrgwm, near Carmarthen

What's here

From 9 May, the mountain bike trails below will also be diverted due to harvesting:


  • Raven Trail

Please follow all instructions and diversion signs on site.


Situated a couple of miles from the village of Brechfa, the Byrgwm car park is the starting point for mountain bike trails through Brechfa Forest.

Inexperienced off-road cyclists can get an introduction to mountain biking on the Derwen Trail which flows through the oak woodland.

The black-graded Raven Trail was designed by two well-known mountain bikers and it will test the skills of experienced riders.

The walking trail passes a derelict smallholding, one of several ruins throughout Brechfa Forest.

The woodland boasts some huge Douglas Fir trees and plant enthusiasts should look out for hard fern, broad buckler fern and bilberry.

There are portable toilets in the car park.

Walking trail

The walking trail is waymarked from start to finish.

Look out for the information panel at the start of the trail.

Find out about walking trail grades.

Byrgwm Walk

  • Grade: Moderate
  • Distance: 4¼ miles/6.8 kilometres
  • Time: 2½ hours
  • Trail information: Requires a reasonable level of fitness. Walking boots and waterproofs recommended. Paths can be slippery when wet. Please watch out for mountain bikes, as they share sections of forest roads

This walk takes in views of the Cothi Valley, airy woodlands with huge Douglas fir trees, darker moss strewn Norway spruce areas, and a derelict smallholding.

Don’t be put off­ by the forest road ahead – soon views of the Cothi valley open up to your right with its landscape of farms and woodlands.

After just under a mile you will turn left leaving the road to go along attractive woodland paths.

Mountain bike trails

All our mountain bike trails are waymarked from start to finish and have been graded for difficulty.

At the start of the trail there is an information panel – please read this before setting off.

Derwen Trail

  • Grade: Green (easy)
  • Distance: 9.7 kilometres

Typically, green trails are all on forest roads or canal towpaths – but not in Brechfa Forest! We aimed to create a trail that engages the rider and heightens your senses giving a true taste of off­-road riding.

Named after the oak woodland it effortlessly flows through, the Derwen trail gives the inexperienced off-road rider a unique introduction to the world of mountain biking.

Clinging low to the valley sides, the trail eases you in with steady climbs and fun descents. Weaving through the forest you will encounter some lovely scenery and flowing terrain.

One ride will have you hooked and, perhaps, thinking of trying out the blue-graded extension.

Derwen Trail (extension)

  • Grade: Blue (moderate)
  • Distance: 3.9 kilometres (extension to the Derwen Trail)

This extension to the green-graded route climbs a steeper bank before taking in a longer, faster descent that will have you pumping and whooping all the way to the valley bottom.

This route is also a stepping-stone to the steeper and more technical red-graded Gorlech Trail from our car park at Abergorlech.

Raven Trail

  • Grade: Black (severe)
  • Distance: 19.1 kilometres

Suitable only for proficient bikers, the trail effortlessly mixes up the more traditional narrow woodland singletracks with Brechfa’s signature brash descents: fast, undulating trail that sweeps between trees and flows sinuously into berms and over jumps.

This trail takes you out into the more interesting corners of the forest and creates a ride that involves the forest’s unique environment, from spooky mossy overhangs to the magnificent Douglas fir Northshore Bridge.

Designed by Rowan Sorrell and Brian Rumble, this trail will test your full artillery of trail skills.

Brechfa Forest

Brechfa Forest is the modern name for part of the ancient Glyn Cothi Forest.

Glyn Cothi Forest was managed for centuries by local people in order to provide building materials, products and grazing.

In 1283, following the final defeat of Wales by Edward I, Glyn Cothi became a Royal Forest administered under Forest Law for several centuries.

Since those days a very different forest has developed. In the 1900s Brechfa Forest was replanted with conifers by the Forestry Commission to boost Britain’s timber reserve after the heavy use of timber in the First World War.

Today Brechfa Forest covers some 6500 hectares and is looked after by Natural Resources Wales for the benefit of people, wildlife and timber production, and more recently the production of wind energy.

Other car parks in Brechfa Forest

There are walking and mountain bike trails from these other Natural Resources Wales car parks in Brechfa Forest:

  • Abergorlech - woodland walks, a mountain bike trail and an arboretum with a difference
  • Gwarallt - easy short walk through beech woodland
  • Keepers - choice of riverside trail or long walk past huge wind turbines
  • Tower - forest walk with valley views and access to trail past wind turbines

National Forest for Wales

Brechfa Forest forms part of the National Forest for Wales.

The National Forest will:

  • create areas of new woodland
  • enhance existing woodlands
  • restore Wales’ irreplaceable ancient woodlands.

In time it will form a connected ecological network running throughout Wales, bringing social, economic and environmental benefits.

For more information about the National Forest for Wales go to the Welsh Government website.

Opening times

Please check the top of this page for any changes to these opening times.

The portable toilets are open at all times.

Closures and diversions

Sometimes we need to close or divert trails for your safety whilst we undertake maintenance work or other operations.

We may have to close a site in extreme weather, such as high winds or snow and ice, due to the risk of injury to visitors or staff.

Please always follow any instructions on site and any temporary diversion signs.

How to get here


Byrgwm is 2 miles north-east of Brechfa village on the B4310.

It is in the county of Carmarthenshire

Ordnance Survey map

Byrgwm is on Ordnance Survey (OS) Esplorer map 186.

The OS grid reference is SN 544 315.


From the A40 between Llandeilo and Carmarthen, take the B4310 towards Brechfa village.

Public transport

The nearest train station is in Carmarthen.

For details of public transport visit the Traveline Cymru website.


Car parking is free of charge.

Overnight parking is not permitted.

Contact details

There are no staff at this location.

Contact our customer team for general enquiries during office hours, Monday to Friday.

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