Big Mountain rides in Wales?

I am planning a trip to mid / north Wales and want to include a couple of big mountain rides with some trail centre riding. I am not sure where I will be based yet but thinking of Dolgellau.

Any suggestions of good rides? Last year I did the loop from Capel Curig around the lake that was in MBR, plus Cader Idris. I'm after fast rocky descents and that big moutain feel. As little a push factor as can be managed is preferred.

Any help is greatly appreciated.

Cheers
Rich

Snowdon mate? We did it last weekend, despite the rather aweful weather it was some of the best riding i've done in a while.

Sarn Helen, Pont Scethin?

http://www.dyfimountainbiking.org.uk/Dyfi_MTB/Welcome.html

http://www.flattyresmtbroutes.com/WalesRoutes.html