Thanks Mikey that's what I wanted to hear! What's the quickest way to the top of the downhill then (on a bike) without an uplift? – Up the Twrch?
quickest way is to ride up the road probably, but there's not much fun in that.
Cwmcarn is alright for a hard blast. The climb is a bit demoralising on a hardtail though, even worse if you're unfit. The descent is very disjointed and not as fun as perhaps it could have been. The freeride section at the top is good fun if you stay up there and ride it a few times.
I've done bits of the downhill track. Starting from the concrete road tunnel. If you get to a part of the XC course where you go up a steep concrete path after a little descent, turn right on the road and follow down the road bearing left for a couple of hundred yards and there's a wooden fence on the left you can start behind. It doesn't take very long to get down to the car park from there!