This is one of my favourite summer evening runs because it gets the last of the days light really well because it's open all the way to the north horizon.
I normally go round the Pentlands clockwise on the A701and finish on this route.
Hardly ever see any cars I have to overtake :-)
Dont go miles out of your way its not that great but if your in the area its a bit of a laugh. One really good sweeping left-hander near the start then the main features are the roller-coaster humps, two up loaded on a tourer your suspension and breakfast will be working overtime, on a sports-bike its a hoot and minimises front tyre wear.
Fed up of taking the M8 (hateful road) between Edinburgh and Glasgow? Try this instead. Carluke to Glasgow is orrible, but the section between Balerno and Carluke makes up for it. Some nice bends as you come out of Balerno, but speed limit stays at 40.
BEWARE: the initial road surface out of Balerno is like a farm track, it is VERY bumpy. It is straight however, so unless youre on a 750 kawasaki you should be ok.
It is mostly straight with one or two corners, but this is not a place for lining up corner after corner.
Where this road scores highly though is the traffic, or rather the lack of it. I once saw a milk lorry on this road. And I once saw a car. One time I saw a gsxr 750. Thats about it. This road is empty.
The scenery isnt bad, mostly open country, so visibility is great, it has the occassional forestry commission forest.
Once you get to Carluke though the fun is over. Traffic becomes heavy, speed limit is mostly 50 to Glasgow, scenery is dreadful, and youll have to use a section of the M8 (spit) if you dont want the journey to take 2 hours.