Want to do some XC tomorrow. I know there's quite a few decent routes in the Brecons (indeed I've done the Gap and the Crickhowll Mynydd loops before). But what is there closer to Cardiff? Anything worth exploring? As a DHer I know there's plenty of forested hillsides in these valleys – Mountain Ash, Abercarn, Cwmcarn, Gethin, Rheola etc etc. The DH is numerous. Are there any accompanying XC rides, apart from Cwmcarn's main loop?

Looking for something 15-25miles I guess. A map/directions would be great, but failing that give me some hints/pointers and I'll get busy with the OS map.

Cheers all!

Have a GPX of a niceish loop around cardiff on my work computer.. I think! Give me an email shall send it to you tomorrow… Stephen.Hodge(at)plymouth.ac.uk

Cheers Steve, have emailed you. Anyone else?

Absolutely tons on your doorstep, ideally need somebody to show you the best bits, but an OS map and a bit of time will help.Here's a list of join the dots place names for a route to follow, with the aid of the map you may find some good stuff.
Taff trail out past Radyr wier, left over foot bridge into Morganstown, rear of Pentyrch quarry(behind Ty-Nant inn), right into woods as you exit quarry workings at gate for short climb and muddy downhill.Cross Pentyrch hill into Coed-y Bedw(go left and follow a loop back down from the top) to the Garth Cottages (Gwaelod Y Garth), take a left to head over the Garth itself, down the back into Gwaelod again.Cross Taff, head for Castell Coch, Ridgeway Path towards Machen, Rudry, Caerphilly Mountain, Wenallt, Castell Coch, Taff Trail back to Cardiff.

This could well be what you're looking for:
http://www.singletrackworld.com/trailguide/uk/wales/between-trail-centres-south-wales/

There's LOADS of excellent riding around Castell Coch, The Wenault, Caerphily, a bit of time with an OS and you can easily get an all-day ride out of it.