Well surfaced open bends, not a lot of traffic. You can get some serious speeds along this road. (Can be used as an alternative route for the Sunday Glasgow to Inveraray run. At Garelochhead turn right to head up to Arrochar and onto the A83). Some nice bends and steep ups and downs make this road like a fast roller coaster ride. (Myth has it that several years ago some bikers closed the snow gates at either end of the road and used it as a private race track for several hours before the police helicopter was scrambled to catch them).
The road is the the upper of the two faint lines on the map, next to Auchinvennal. You enter from the A82 just about where Shantron is and exit where the middle A814 is.
The route isn't actually shown on the map. From Arden continue North on the A82 and take the 2nd exit left (not shown) signposted for Garelochhead. The road follows closely the contours of the landscape and offers good views of Loch Lomond and the Gareloch.
There are some really good fast sweepers on this route, it was formerly an MoD road that was later opened to traffic. Great fun but watch out for small animals