h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Mountain bikes (cross country bikes) are actually very light efficient machines. My current machine weighs in at 23 lbs even with 4in front suspension. Mot bikes made of aluminium, steel or titanium weigh a little less or not much more, if they have light wheels, etc.. When you have to peddle up a steep climb off in the woods that weight really counts.

Full suspension downhill bikes are heavy (35lbs eg.) and are more-or-less motocross bikes with peddles.

I rode an old Halfords sport-touring bike many moons ago for many years (after my 12 speed Raleigh lost favour). I rode it until I discovered mountain biking. It was fitted with a Brooks saddle which lasted over a decade. It was an awesome saddle after being broken in a bit. I find on my mountain bike saddle you need a bit of strength and give so the bars don't break when you take a hard jolt and maybe some padding - and preferably all of this in a slim saddle so it doesn't get in the way. The old saddle probably fits all of these desing criteria and the leather would really work well, but I can't seem to find them here in Canada.

Still sold at St John Street Cycles, whose website you might find if you tried SJS Cycles with no space in the UK corporate domain (as per the normal BBC URL).

Heaven forbid that I should actually post anything as seditious as a URL, though.