In reply to alex_frost33:
John Shirt Motorcycles, for many years the main British importers of Gas Gas off road motorbikes are based in Harpur Hill, so no surprise that off road bikes are often seen in the quarry, probably have more legitimate right to be there than climbers.
I'll declare an interest here, as well as being a climber I was also a trials bike competitor for a few years, competed against the Gas Gas lads many times in the Peak district, although not up to their standard they were always a pleasant crew.
John Gresty