Allt Rhyd Y Groes National Nature Reserve
Allt Rhyd Y Groes National Nature Reserve
4.0
(13)
177
riders
12
rides
Mountain biking around Allt Rhyd Y Groes National Nature Reserve offers a diverse landscape of valleys, forests, and reservoirs, providing varied terrain for cyclists. The region, situated in Carmarthenshire, features a mix of moderate climbs and descents through wooded areas and open countryside. Trails often follow river valleys and offer views of the surrounding natural environment.
Last updated: May 7, 2026
2
riders
26.8km
02:28
550m
550m
Moderate mountain bike ride. Good fitness required. Suitable for all skill levels.
5.0
(1)
11
riders
33.9km
03:09
770m
770m
Moderate mountain bike ride. Good fitness required. Advanced riding skills necessary.

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2.0
(2)
37
riders
Moderate mountain bike ride. Good fitness required. Suitable for all skill levels.
8
riders
62.4km
06:02
1,370m
1,370m
Hard mountain bike ride. Very good fitness required. Suitable for all skill levels.
2
riders
37.5km
03:06
700m
700m
Moderate mountain bike ride. Good fitness required. Suitable for all skill levels.
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Popular around Allt Rhyd Y Groes National Nature Reserve
Hiking around Allt Rhyd Y Groes National Nature Reserve
Cycling around Allt Rhyd Y Groes National Nature Reserve
Road Cycling Routes around Allt Rhyd Y Groes National Nature Reserve
Gravel biking around Allt Rhyd Y Groes National Nature Reserve
Running Trails around Allt Rhyd Y Groes National Nature Reserve
Cwm R MTB trail is completely blocked at top end due to hundreds of wind fallen trees this winter. Please consider before as you can not navigate loop.
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A short climb up from the road brings you to the Dam and carpark, there is no access over the Dam itself. But you do get a good view over the spillway and valley below.
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Built in 1913 the Rhandirmwyn Bridge links the two sides of the Towy valley by this rivetted girder road bridge. On the southern side you'll find the Towy Bridge Inn, a lovely riverside pub.
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THE TALE OF THE WELSH “ROBIN HOOD” Known as Twm Siôn Cati Twm Siôn Cati is a historically known figure in Welsh folklore. A tale recounted by Meyrick recalls how Twm was asked by a poor man to steal a pitcher for him. They went together to a merchant where Twm started belittling the man's wares. Having told his friend secretly to take the pitcher of his choice, Twm distracted the merchant by telling him there was a hole in one of the pitchers, which the man denied. Twm desired him to put his hand in the pitcher to test it and the man still denied there was a hole. Twm then asked him how, if there was no hole, could he have put his hand inside? By this time his friend had disappeared with his pitcher, undetected. A tale from Prichard's book involves an occasion when Twm is staying in an inn overnight and realises other people are planning to rob him the following day after he sets off. He has a large sum of money with him. The following morning he behaves as though his money is in the pack-saddle of his horse. When the highwayman catches up, Twm drops the saddle in the middle of a pool. The highwayman wades into the pool to fetch it, Twm takes the opportunity to make off with the highwayman's horse. A complication arises because the horse responds to the voice of the highwayman crying "Stop!" Luckily Twm, in terror, happens to shout a word which makes the horse gallop on again, and he is conveyed to safety. Another tale recounts how Twm waylaid a rich squire, who was accompanied by his daughter, Twm was so smitten with her that he returned her jewellery to her and attempted to woo her, against her father's opposition and, initially, her own. One full moon shortly after the robbery, he crept to her window, roused her from sleep, caught her hand at the window and kissed it, refusing to let her go until she promised to marry him. She wouldn't promise so Twm drew his dagger, drew blood on her wrist and threatened to sever her hand unless she assented to marriage forthwith. She agreed to marry him and she kept her hand. Their marriage followed soon after, despite her father's views and the directness of Twm's courtship methods. The girl was supposedly the widow of the sheriff of Carmarthen. Through this marriage Twm is supposed to have gained respectability, eventually becoming a justice of the peace, sitting in judgement on others, a position he held until his death aged 79.
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More stunning forestry gravel that links the Tregaron mountain road over towards Tyn y Cornel hostel.
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Lovely mix of fire road to start with and then a huge climb up and over into a valley that time forgot - perfect single track - although can be a bit muddy in places. Probably best to make sure there has not been too much rain in the week before riding this route - and in the winter be prepared for quick changes of weather and plummeting temperatures.
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There are 12 mountain bike trails around Allt Rhyd Y Groes National Nature Reserve, offering a variety of experiences for different skill levels.
Yes, there is one easy mountain bike trail available. While specific family-friendly trails aren't highlighted, the easy route provides a good starting point for less experienced riders or families looking for a gentle ride.
The trails feature a diverse landscape of valleys, forests, and reservoirs. You can expect a mix of moderate climbs and descents through wooded areas and open countryside, often following river valleys and offering views of the surrounding natural environment.
Absolutely. For experienced riders seeking a challenge, there are 6 difficult mountain bike trails available. These routes often feature more significant elevation changes and technical sections.
Many of the mountain bike routes in the area are designed as loops. For example, the Waterfall Viewpoint loop from RSPB Gwenffrwd-Dinas and the Doethie Valley and Llyn Brianne loop are popular circular options.
Spring and autumn generally offer the most pleasant conditions for mountain biking, with milder temperatures and beautiful scenery. Summer can be great, but be prepared for potentially warmer weather. Winter riding is possible but trails may be wet and muddy, requiring appropriate gear.
Trail distances vary significantly. For instance, the Waterfall Viewpoint loop is about 16.6 miles (26.8 km), while the Llyn Brianne Dam loop is a more extensive 38.8 miles (62.4 km).
Allt Rhyd Y Groes is a National Nature Reserve, making it an excellent location for wildlife spotting. Keep an eye out for local bird species, red kites, and other native animals, especially in the quieter forest and valley sections.
While popular routes like the Twm Siôn Cati's Cave – Llyn Brianne Dam Crossing loop offer well-trodden paths, exploring the numerous forest tracks and less-frequented sections around Llyn Brianne can reveal quieter, equally rewarding experiences away from the main routes.
The area is highly rated by the komoot community, with an average score of 4.0 stars from more than 10 reviews. Reviewers often praise the varied terrain, scenic reservoir views, and the sense of wilderness found on these trails.
Parking is generally available at key access points such as RSPB Gwenffrwd-Dinas, which serves as a common starting point for several routes, including the Waterfall Viewpoint loop.
While the immediate vicinity of the nature reserve is quite remote, you can find pubs and cafes in nearby villages and towns such as Rhandirmwyn or Llandovery, which are a short drive from the main trailheads.
The trails consist of forest tracks and open sections. Conditions can vary with weather; expect some muddy or wet sections, especially after rain, and potentially loose gravel on some climbs and descents. Always check local weather forecasts before heading out.


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