Yep, plenty of stuff to keep you occupied, and while there's not masses of super tech singletrack, what there is should be fairly weatherproof.
You can do the Ardgartan peninsula route, a 50k loop starting and finishing in Arrochar. Its not amazingly technical, and after the initial climb and descent on the slopes of the cobbler it turns to fire road for about 15k or so. After that it becomes forestry path which can be as exciting as you want to make it. Its a good loop as it will be pretty weatherproof and offers some amazing scenery if the conditions are right.
There's also the loop up Glen Loin into the Coire Grogain. More boring fireroad to begin with, but the scenery improves as you get into the hills and the final descent is pretty good.
If you're up for some road miles to begin with the climb into Glen Douglas from Loch Lomondside is decent (by road standards) then finishes with a fairly steep descent on an old land rover track. Again, its not black graded but is pretty good fun and the views of the Cobbler should be pretty good.
These routes are all in "Mountainbike Highlands" by Kenny Wilson, but they're all on OS maps too.
I can also recommend the Kenny Wilson book. There are three routes in there that you can start from Arrochar. The Ardgarten peninsula route is the waymarked one and very fine it is. Did it clockwise fairly recently – fantastic views all the way round, some fast descents although only a little bit of singletrack but those views….
The train journey along the loch is great, the conductor takes it upon himself to give you a wee commentary. Problem is, Loch Long is quite, well, Long, so it goes along the lines of
*crackle* "Ladies and gentlemen, we are currently traversing above the banks of Loch Long. Loch Long on the left hand side"
ten minutes later
*crackle* "ladies and gentlemen, on your left hand side is Loch Long, Loch Long on the left hand side"
another five minutes
*crackle* "…still Loch Long…"
and then he either forgot the name of the famous mountain overlooking Arrochar, or he'd lost the will to go on after talking about Loch Long for twenty minutes. Brilliant train journey, look forward to it every time.
From Arrochar you can also wander down to Lochgilphead have lunch in the The Smiddy Bistro (or the Oyster Bar on the way if its more your style)and take a quick spin around the Fire Tower Trail – not forgetting to cast your eye over the Cup and Rings http://home.freeuk.net/jenny.blain/cuprings/achnabreck.html on the way round.
(be wary of the dashed lines that cross temptingly between lochs in that part of the world – some are difficult bog trots)
of course, if you're heading to Lochgilphead it would be criminal not to do the Auchindrain loop from Inveraray, which would be particularly appetising at this time of year! 😆
Walked Glen loin route last week, would make a nice wee 2hr ride to cure a hangover – do it in reverse from the way I walked it though… start up the cobbler path, right onto fireroad then follow it round (great views), past loch sloy and downhill until the farm and glen loin turn off to the right (look for a mass of pylons), its a nice downhill to arrochar and a few steep bits.
If doing the Glen loin loop, start at Tarbet train station, adds a few extra miles and a couple of short steep lung busting climbs, all well worth the effort. And if you are still feeling up for it head up the cruach tarbet, though this does require a wee bit of pushing/carrying. Also if you are in a carrying mood how about tackling the Cobbler or Ben Ime, both of which are great decents.
I agree with Steve_B with regards to the condition of Auchindrain, even by our standard's the weather has been really wet over the past few week's. I was up the firetower trail's last night in pishing rain and they were basically river's 😯 but i do think they are worth a trip at new year, Arrocher to Lochgilphead is about an hr's driving so not far 🙂
Slight hijack:
Steviegil, us from Dunoon are planning to do the Cobbler on Sunday 13th if you're interested. Stewart & Sinclair did it in the summer… Flikr linky
I would have loved to Rob but im taking the kid's to Edinburgh for the christmas market in Princess street gardens 😯 😆 thank's very much for the offer though 8)