Are there man-made trails in the forest then? Hadn't realised! It looks like I'm the slowest subscriber so far & I think you've an idea of what I'm up to (second loop on Sunday would've been ok, but I would have held you up), so should be cool 8)
There's nothing man made in the trail centre definition of man made, but all the trails in the forest are either surfaced forest roads or paths.
It's a long way from being a trail centre thankfully.
The forest officially and legally opened up to bikers in 1994 when the 'forest bridleway' was designated. (I remember it well!)
'Charity Lane' which runs along the forest boundary is a rocky old unsurfaced and largely unmaintained county ride which of course makes it a great descent, especially when combined with a narrow track called 'Bottom of the Oven'. Riding in the southern half of the forest is mostly on a network of permissive bridleways on forest tracks. There have been a few new bits put in which are aimed at keeping bikers happy.
Out towards the north there is more good riding an a few bridleways and tracks, and to the east you can head out and up onto the moors for some great routes.
The good riding isn't always obvious on the map, but it is possible to piece together all the good bits.