Brechfa Forest – Byrgwm, near Carmarthen

What's here

There are diversions on the walking and mountain bike trails at this site - please follow all instructions and diversion signs on site.


Coronavirus update


Our sites and most visitor facilities are open.


We have changed the normal route for some of our trails to help you maintain social distancing – please follow signs on site.



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.

Visiting Brechfa Forest

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

There are walking and mountain bike trails through these two woodlands within Brechfa Forest:

There are also walking trails in other places in Brechfa and horse riders are welcome on forest roads.

Byrgwm, Brechfa Forest

Byrgwm means “short valley” in Welsh and the woodland boasts some huge Douglas fir trees.

The waymarked walking trail passes a derelict smallholding, one of a number of similar ruins throughout Brechfa Forest. These are a poignant reminder that more people used to live off the land here.

Mountain bikers of all abilities can enjoy the woodland, too, as there is a trail for beginners and families and a black route for proficient riders.

Walking trail

The walking trail is waymarked and starts from the car park.

Byrgwm Walk

4 miles, 6.4 kilometres, moderate

This walk goes through airy woodlands with huge Douglas fir trees and darker moss strewn Norway spruce areas. It passes a derelict smallholding and offers views of the Cothi Valley.

Mountain bike trails

All of the mountain bike trails are waymarked and start from the car park.

See our mountain biking page for a list of all our mountain bike trails and information about grading to make sure you pick a trail that is right for you.

Please also read the relevant onsite information before setting off on your ride.

Derwen Trail

9.2 kilometres, grade green

Typically, green trails are all on forest roads or canal towpaths - but not in Brechfa Forest! 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 with some steady climbs and fun descents.

Derwen Trail

4.2 kilometres, grade blue – extension to the green Derwen Trail

This an extension to the green Derwen Trail which you join halfway along the green route. It then climbs a steeper bank before taking in a long, fast descent and rejoining the green trail to return to the car park.

Raven Trail

18.5 kilometres, grade black 

The Raven Trail was designed by Rowan Sorrell and Brian Rumble, who are well known in the mountain biking world.

Suitable only for proficient bikers, the trail takes goes out into the more interesting corners of the forest. It mixes up the more traditional narrow woodland singletracks with some brash descents and fast, undulating trail between trees, into berms and over jumps.

Opening times

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

The toilets are portaloos which are open at all times.

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.

How to get here


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

It is in the county of Carmarthenshire

Download the location map.

Ordnance Survey map

Byrgwm is on Ordnance Survey (OS) 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


Car parking is free of charge.

Overnight parking is not permitted.

Closures and diversions

Please note:

  • Sometimes we need to close or divert trails for your safety whilst we undertake maintenance work or forest operations
  • Occasionally 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 onsite and make sure you follow any temporary diversion signs in place

Contact details

Tel: 0300 065 3000


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