National Cycle Routes 8 and 82 make up the Mawddach Big 8 cycle routeNational Cycle Network Route-8, known as the Lôn Las Cymru, runs over 400 km (250 miles) between Holyhead on Anglesey and Cardiff or Chepstow, and is reckoned to be one of the toughest routes of all the Network.

In its original form, the way-marked trail offered a number of route alternatives along its length, and as the heart of a number of decision points, the town of Dolgellau had Route-8 markers leaving in four different directions. The two Route-8s (or should that be Routes-8) heading north from Dolgellau converged just east of Porthmadog, and those heading south met at Machynlleth.

Fortunately wisdom has prevailed, and this confusing situation has been remedied by the renaming of the trail running through Trawsfynydd/Dolgellau/Tywyn as Route 82. Either way, this leaves Dolgellau on the Mawddach estuary at the centre of a cycleway-drawn number 8, the 160 km long ‘Mawddach Big 8’ (MB-8).

Big 8 bicycle route mapThe MB-8 makes use of quiet back-roads and tracks, although there are a few forays onto busier roads. The tracks, although rough in places, involve no technical mountain biking and with care should be passable on a hybrid bike or tourer. The roughest of these is probably the Ffordd Ddu on the South Loop. Having said all that, this is not a route for the faint-hearted, as the distance alone will testify; each of the routes leaving Dolgellau to the north or south is graded as strenuous, and each loop of the MB-8 consists of two of them! Add in over 4,500m of climb along the way, and the scale of the challenge starts to take shape.

For a rider to be considered an MB-8 elite, the journey should be done as two back to back 1-day rides, the North Loop and the South Loop.
Double-Loopers will do them back to back on the same day. Of course, mere mortals are also welcome, and are encouraged to break up the journey as required.

Dolgellau, at the meeting point of the two loops, is a logical starting point, although Penmaenpool, Barmouth or indeed anywhere along the Mawddach estuary would make an excellent base for tackling the challenge. The estuary boasts a wide range of bike-friendly accommodation to suit all pockets, as well as some seriously good places to eat and drink. As the route constantly dips in and out of small villages, there are shops and pubs along the way that will be glad to help refuel weary legs

The route is way-marked with blue and red National Cycle Network Route-8 and 82 signs but we recommend you carry suitable maps as a back-up. The North Loop is covered by OS Landranger Map 124, while the Southern Loop is on OS Landranger 135

Alternatively, Sustrans offer a 1:100K Route 8 North map which includes the entire MB-8 and more.

Those of a strictly road-biking persuasion (or even in a car) can follow the loops formed by the A 496 and A 470 to the north, and A 493 and A 470 to the south. Be warned that these narrow roads can be very busy in the holiday season. The A-road route is slightly shorter at just over 150 km, with just over 4000 m of climb. Don’t try doing the actual Route-8 in a car; bits are on tracks not open to traffic, many of the roads are very narrow and steep, and the whole thing was originally laid out to give cyclists a relatively traffic free experience.

FREE GPS DATA: Big-8 North Loop GPX

FREE GPS DATA: Big-8 South Loop GPX

In addition, a Mawddach Big-8 guide book is available to buy which contains further route details, background information and historical detail. This can be a bought as a printed booklet or an electronic pdf file:

Printed Guide
An electronic (adobe pdf) route guide to the Mawddach BIG-8 will be emailed to you within 48 hours.
A bound, A5 booklet version of the BIG-8 route guide will be dispatched to you by first class post.
Only £3.99
Only £8.99
inc UK P&P


Cycle Route Difficulty

Mawddach Trail Easy Cycle Route
15 km (9.5 miles)
A flat and friendly there-and-back route following the old railway line along the Mawddach estuary. More...

Mawddach Trail + Cregennen Challenging Cycle Route
23.8 km (14.8 miles) 501m climb
A circuit taking in the the Mawddach trail and the beautiful Cregennen lakes. More...

Dolgellau-Bala Loop Difficult Cycle Route
78.9 km (49 miles) 4500m climb
A big road ride taking in the remote moors at the back of Coed y Brenin. More...

Mawddach Big-8 Difficult Cycle Route Difficult Cycle Route
160 km (99.4 miles) 4500m climb
An epic 2-day ride. Following National Cycle Network Route-8 in a figure of 8, with the Mawddach estuary at its centre, you will ride for around 8 hours and cover around 80 km each day. Its octastic! More...

Coed y Brenin Easy Cycle Route Challenging Cycle Route Difficult Cycle Route
World class trail-centre mountain biking with 7 different trails to chose from. Trail heads and visitors centre 12 km from Dolgellau. More...

Cli-Machx Difficult Cycle Route
Short but sweet trail centre mountain biking. Trail Head 19 km from Dolgellau. More...

Mach 1, 2 & 3 Easy Cycle Route Challenging Cycle Route Difficult Cycle Route
Real trails with a trail centre feel. Trail Head 25 km from Dolgellau. More...

Antur Stiniog Difficult Cycle Route
For those who like their mountain biking gravity-fuelled, the the Antur Stiniog downhill courses run through the slate quarries of Blaenau Ffestiniog, about a 30 min drive from Dolgellau . More...

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