Closest spot would be Buck pub on Cowpe Rd landlord there is a keen mountain biker and is happy for you to use the pub car park, especially if you pop in for a half afterwards.
From the pub car park cross the road and follow the Pennine Bridleway up the hill, keep going up the hill, then up some more and up even more! If you can ride it all without dabing (getting off and walking is more likely) you are doing really well!
At the top of the hill follow the pennine bridleway signs to the left and youll find yourself in Cragg Quarry. Still haven't got the proper signage up there yet so a bit of exploring is required but its worth it.
Alternative is to park up at Lee Quarry and find a cheeky route over the moors from the top end of the quarry, follow the red route round to where it climbs up the back of the quarry with a big drop on your right. Look for a track off to your left and follow the tyre marks and rutts over the moor. When you get to Rooley Moor Rd turn right and you'll find yourself in Cragg after 5 min or so.