I carried on past the waterfall but the path gets increasingly steep in places. It was over 30 and extremely humid and I only had one bottle of water with me so it seemed a bit reckless to keep going. So I turned around and tootled around Silvermine Bay area It would be good to have another go when I'm there in the winter I think
I've hiked those trails many times, but since have only taken up cycling recently, haven't really done so with a cyclist's eye. Having said that, once you get up the steep part of the Olympic Trail (concrete path going past the waterfall) which ends a bit after the actual Silver Mine caves, then the gradient becomes more tractable. Keep going and you could ride the Olympic Trail down to Pak Mong Village on the other side of Lantau -- leaving you with the small matter of somehow getting back over the hump to Mui Wo to drop off the bike at the shop. Or you could throw a right up top and cycle off concrete at least part of the way along the hiking trail toward Tiger's Head (Lo Fu Tau) ... pretty sure a MTB could get as far as the back of Discovery Bay Golf Course. (I'm not clear on the legality of MTBing off the Olympic Trail - would certainly need a permit if allowed at all).
The climate's really something in summer. With hikes, I tend to figure out where I want to end up, how long it will take me to get there, and then work backward from end of Civil Twilight to pick my starting out time. Wouldn't be keen to be out in the midday sun for sure.