I'm no expert, but...
Park at the top Wharncliffe car park, on the way north out of Grenoside. Cross the road and go straight up into the woods (blue line opposite parking).
Pub Run (and variants) starts on a small singletrack directly ahead at the first junction, just left of a massive motorway bridleway. Keep veering right (they've recently rebuilt it - use to be more natural on the top bit, now it's jumps etc...). Or watch out for left turns for big jumps in the clearing. Gets muddy in the clearing. Push up the trails, or the bridleway motorway.
For Steel City, turn left at the first junction and head uphill. Watch out for a starting ramp on the right at top of hill. Follow your nose. At bottom, push/ride up wide track to the south.
For DH3 (I think that's what it's called) keep going past Steel City and look on right. Variants here.
Trails are more peddally, less steep than Wharncliffe. Push up isn't very steep on the two wide tracks marked. The more recent, manufactured stuff holds up better in the wet.
I'm sure Fatdoc or someone will have more info.
