Ah no! That was at Gospel Pass, just north of the car park on the way over from Llanthony to Hay-On-Wye.
There is a slight blind rise and the road dived right as you crest it with a gravel track going straight on and down. Luckily the GS, two up, managed to pile up enough gravel in front of the tyre to stop otherwise we would still have been in free fall somewhere above the town of Hay...