The first half of this route is almost entirely off-road. Once you have climbed to the base of Mynydd Troed you follow a bridleway (much used by horses, so it gets quite churned up in wet weather) through bracken. From Cwm Siencyn, it’s up onto the top of Cefn Moel and down, down, down to the village of Bwlch. From Bwlch you go up to the knife edged ridge of Allt yr Esgair with its impressively sited Iron Age hill fort. Take a while to gaze at the views and imagine how life was for those Iron Age folk. Descend, now, on a narrow path to Pernorth and make your way back to Talgarth following bridleways and lanes around Llangorse Lake and surrounding area.
More information can be found here: http://www.mtbbreconbeacons.co.uk/english_pages/hubs.htm