Drum Mountain is a good ride. Take a look on http://flattyres-mtb.co.uk
for some great ideas

Up north.
Cadair Berwyn is 830m (does'nt feel like it) via bwlch Maen Gwynedd and the Wayfarer's.
Pont Scethin.
Llyn Colwyd.

The Gap.

Drum with a detour up to Llyn Anafon if you want smooth and fast, Llyn Cowlyd and Llyn Crafnant (ace cafe) if you're radder than Chester Greenway.

And the quarry at Dinorwic.
Stunning place.
And another ace cafe, Dinorwic Lodge, just down the road.

Cowlyd when its been frozen hard or dry for quite a prolonged period. Drum is great...probably the fastest ive been on an MTB

Thanks for the pointers, will acetone get the maps out.
Keep them coming

Brecon Gap, which I did this morning. Or for something slightly different (steep up and down) from The Garth to Cwmcarn via Castell Coch, Caerphilly Mountain, Rudry, Machen and Wyile (and back).

I'd say

Pont Scethin
Berwynion
Cowlyd (but you need a bit of masochism)
Elan Valley
The Gap, Brecon Beacons
Black Mountains (Grwyne Fawr/Grwyne Fechan)

For starters

Plug alert: I wrote a book about all this once 🙂 https://www.amazon.co.uk/Wales-Mountain-Biking-Tom-Hutton/dp/1906148139

Drop me an email if you need any more info (email is in profile).

And enjoy!

Or GPXs 🙂