I'm working in Caerphilly and Merthyr Tydfill on Monday and Tuesday and want to squeeze in two or three hours of riding. Done Afan(Whites Level) and love it but quite keen to try somewhere new, any suggestions?

Cwmcarn's not to far from Caerphilly, there's some good riding around machen / castell coch area too but you need someone who knows that to get the most from it…

Good trails in Gethin Park Merthyr, woods around Castell Coch (just outside Cardiff). Both require a bit of local knowledge to get the best out of though. Failing that Cwmcarn!
beat me to it there Colin!

Merthyr is at the foot of the Brecon Beacons so plenty of riding if you head North (like The Gap).

Lots of routes out of Caerphilly – there was a route guide in singletrack mag (or maybe mbr) not too long ago.

Also I've heard that there are good trails out of Bargoed.