Cwm Penmachno Climb

Translated from the other comment...

A pig of a climb! Steep for most of the climb from the first moment at the junction with the telephone box. Slightly easier for a while after the first cattle grid, but it is steep until the end beyond the second cattle grid, and soon it feels like a different world on the Migneint. Finishing near Ffynnon Eidda, where the words 'drink and be thankful' - you will need water and climbing legs for this.

The village was built in the 1860s as a quarry settlement. The Penmachno quarry lay immediately south and above the settlement. Higher up the valley was the Rhiwbach slate quarry, which was formerly linked by the Rhiwbach Tramway to the Ffestiniog Railway at Blaenau Ffestiniog. Streams flow from the steep-sided valley, forming the source of the River Machno, which flows through the larger village of Penmachno before joining the River Conwy south of Betws-y-Coed.
This climb has a Grade of 6.7% for 4.33km evaluation is 293m none as the climb from hell.
You need everything for this one

A pig of a climb! Steep for most of the climb from the first moment at the junction with the telephone box. Slightly easier for a while after the first cattle grid, but it is steep until the end beyond the second cattle grid, and soon it feels like a different world on the Migneint. Finishing near Ffynnon Eidda, where the words 'drink and be thankful' - you will need water and climbing legs for this.