Bwlch Pen Barras is a popular but rather desperate hill climb. The reason for its fierce reputation becomes obvious when you consider the rapid height gain involved. Traditionally it is tackled from the western side where a steep road rises up from Llanbedr, gaining 260m in height in just over 2km. The first kilometre is particularly testing and leads to a steep hairpin bend. If you make it round the bend then the reward is a slight easing in the gradient leading up to the col.
Taken from the east it provides a less testing challenge, with a long straight section at a more reasonable gradient.
At 358m Bwlch Pen Barras is fairly high; consequently during the winter months it is occasionally blocked with snow.
There are various starting points, depending on your intended route, but if you just wish to do the climb on its own then Llanbedr or Ruthin are obvious choices.