When I was a postman I remember we entered a road relay, and thoroughly trounced several local athletic clubs' A teams. I'm pretty sure it was the fittest I've ever been, when I first started I was getting through a loaf of bread a day and having pizza for breakfast to try and cope with the work load. Obviously scaffolders would win on upper body stuff but posties are hard to beat for CV fitness.
They do seem to work ok, however when I calculated my max HR in a stress test with my old decathlon one I got my HR up to 204. Since getting a garmin one I've never managed to get it about 190. I suspect this is due to the old one being shite!
There's a couple of good (and legal) trails further east as well. Penmaen to Parkmill is good, as is Southgate golf course to Parkmill, and Southgate to Pwll Du.
That singletrack route is defo the wrong way round! Although thinking about it Rhossili Down rides better that way round – south end is most possible to ride up, and north end the most exciting to ride down. Also crossing Bury Pill is better North-South. I would do that ride from Penmaen and finish along the top of Cefn Bryn – for me a downhill finish is mandatory.
I've just pulled some BBBs out after the lower one totally seized a whole 2 months into use. That was one of the cheaper ones, maybe the ceramics are more reliable?
Forgot to say, from the national cycle route you can join up with Skyline whilst you're up there, or drop down to Glyncorrwg, hit the cafe, then do Skyline from the start. From there to the Gap I've no idea though.
mtb-wales is a good place to ask this one. You can take one of the national cycle trails (no 47, up through Neath and over to the east of Resolven) from Swansea to Afan, and then the Skyline to the NE corner and drop down. As for how to negotiate Merthyr I'm not too sure ;o)
The trouble with waterproof gloves (and socks) is that they have a rather large hole in one end. Stay out long enough and water will work it's way through it. I doubt many gloves actually leak through the main section, but it doesn't take much for water to work around the cuff and then soak through the lining.