The pass is on an unclassified road between Tafarn-y-Gelyn and Llanbedr-Dyffryn-Clwyd. It crosses the Clwydian Range at an altitude of 360 metres (1181 feet) between the hills of Moel Famau (to the north) and Foel Fenlli (to the south). The Offa's Dyke Path also crosses Bwlch Penbarras, running north-south.
The pass is a popular access point for walkers venturing to Moel Famau, and as such there are two Forestry Commission car parks: one at the summit of the pass, and one a mile down the eastern side of the pass towards Tafarn-y-Gelyn. Access tracks climb through the forest from both car parks to Moel Famau's summit.
It is also popular with cyclists, especially the notorious climb from the west (Llanbedr-Dyffryn-Clwyd) side: the road gains 260 metres (853 feet) in altitude in just 2.25km (1.4 miles), the first half of which is at a gradient approaching 25%, followed by an even-steeper hairpin bend before the gradient finally eases slightly. As such, the pass has featured in the Cycling Weekly magazine as a 'Killer Climb', and also features in the Dave Lloyd Mega Challenge cyclosportive.
In comparison, the east side of the pass has a less severe gradient, but from the summit it is dead-straight for over a mile downhill, which provides an exhilarating descent for cyclists who have struggled up the pass from Llanbedr.
The alternative name of the 'Old Bwlch' comes from the fact that this pass used to take the through-road from Mold to Ruthin, until it was superseded by the A494 road, which crosses the Clwydian Range a couple of miles south of Bwlch Penbarras, at Bwlch-y-Parc.
It was mentioned in a March 2012 interview by Nigel Blackwell of Half Man Half Biscuit : "the biggest achievement for me is creating a situation for myself whereby I can get up of a morning and decide to go and tackle Bwlch Pen Barras on the bike" (http://www.thevpme.com/2012/03/08/risk-it-for-a-biscuit-half-man-half-biscuit-interview/).