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The Cob Causeway – Llyn Dinas loop from Porthmadog

The Cob Causeway – Llyn Dinas loop from Porthmadog

Hard

298

riders

The Cob Causeway – Llyn Dinas loop from Porthmadog

03:44

78.7km

940m

Road cycling

Hard road ride. Very good fitness required. Mostly well-paved surfaces and easy to ride. The starting point of the route is accessible with public transport.

Last updated: April 7, 2026

Tips

Your route passes through protected areas

Please check local regulations for:

Gwarchodfa Natur Genedlaethol Yr Wyddfa

Parc Cenedlaethol Eryri

Waypoints

Start point

Train Station

Get Directions

1.15 km

The Cob Causeway

Highlight (Segment) • Bridge

This mile-long causeway crosses River Glaslyn as it reaches the estuary. Opened in 1811, this causeway carries the Ffestiniog Railway as well as an A road and a cycle path. Riding along here gives you fantastic views north to Snowdonia’s mountains and across the wetlands of the River Glaslyn. A wall entirely blocks your view south to the estuary, but you won’t care because the mountains are so beautiful from here.

The cycle path is traffic-free so you can easily stop whenever you like to soak up the views.

Tip by

12.2 km

Country Road Along the River in Parc Cenedlaethol Eryri

Highlight (Segment) • Viewpoint

As always great scenery with fresh air some decent climbs well worth it.

Tip by

38.2 km

Royal Oak Hotel, Betws-y-Coed

Highlight • Restaurant

Betws-y-Coed is a village and community in the Conwy valley in Conwy County Borough, Wales, located in the historic county of Caernarfonshire, right on the boundary with Denbighshire, in the Gwydir Forest. It is now a very popular visitor destination in the Snowdonia National Park.
Popular with cyclists a fantastic area if you enjoy a good climb.

Tip by

38.7 km

Bryn Afon Guesthouse, Betws-y-Coed

Highlight • Settlement

Bryn Afon, a property with a garden, is situated in Betws-y-coed, 25 km from Snowdon Mountain Railway, 30 km from Llandudno Pier, as well as 35 km from Bodelwyddan Castle. The property is located 36 km from Portmeirion, 18 km from Bodnant Garden and 36 km from Bangor Cathedral. Free WiFi is available throughout the property and Snowdon is 19 km away.

Tip by

55.5 km

View of Snowdon

Highlight • Viewpoint

62.4 km

Llyn Dinas

Highlight • Natural

Beautiful views across Llyn Dinas from the A498. Snowdon is to the north and the Watkin path starts a little further northeast up the road. Views south up onto Mynydd Llyndy which is managed by the National Trust.

Tip by

63.0 km

Coed Pant-agored

Forest

68.3 km

Stone Bridge over Afon Glaslyn

Highlight • River

The old bridge over the river or Afon Glaslyn is a great place to pause and watch the water go by. You can see down into the Aberglaslyn gorge with the rocky fisherman's path cutting its way along the opposite bank.
The bridge itself is a grade 2 listed 17th century stone construction.

Tip by

68.3 km

Pont Aberglaslyn

Highlight • Viewpoint

The bridge was probably built in the 17th century and then radically rebuilt and widened in 1795-1796. As with many older bridges, folk tales claimed that the bridge was built by the devil or by the Romans (which an investigation by the National Trust described as "very doubtful"). During the reconstruction, a stone was found with the inscription "W M 1656" scratched on it, suggesting that the bridge is at least that old.
Pont Aberglaslyn is located near the downstream end of the Aberglaslyn Pass. Although the location is rocky and the river flows through rapids upstream, it is not far above sea level.
(Wikipedia)

Showing Translation

Tip by

70.2 km

Parc y Llŷs

Forest

76.0 km

Coed Tremadog National Nature Reserve

Nature Reserve

78.7 km

End point

Train Station

Way Types & Surfaces

Way Types

67.5 km

7.76 km

2.55 km

737 m

140 m

< 100 m

Surfaces

74.3 km

4.35 km

107 m

Elevation

Nothing selected – click and drag below to see the stats for a specific part of the route.

Highest point (380 m)

Lowest point (0 m)

Weather

Friday 26 June

24°C

17°C

37 %

Additional weather tips

Max wind speed: 30.0 km/h

to get more detailed weather forecasts along your route

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The Cob Causeway – Llyn Dinas loop from Porthmadog

The Cob Causeway

Country Road Along the River in Parc Cenedlaethol Eryri

Royal Oak Hotel, Betws-y-Coed

Bryn Afon Guesthouse, Betws-y-Coed

View of Snowdon

Llyn Dinas

Stone Bridge over Afon Glaslyn

Pont Aberglaslyn

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