I wouldn't ride on the A689 by choice, but it's a bit unavoidable in places.
Plenty of room there to make a cycle lane too, and it shouldn't be a 70mph road for areas where there are no cycle lanes, not many A-Roads/ dual carriageways should be.
Don't get me started on the Country lanes being 60mph and Motorway's being 70mph, it's ludicrous. Most country lanes should be 40, maybe 50 at best, if visibility is good, and most motorways could be 90mph at off peak times.
A quicker way to solve some problems, is for the local council to take ownership of some of the farm tracks, or compulsory purchase thin strips of land to make cycling short cuts, which would not suit creating roads.
We should be doing all we can to promote safe roads for cycling now, especially with E-Bikes really progressing. Whilst we're at it, up the speed limiter on those to 20-25mph too, and it would get far more people commuting by bike, and much cheaper, a lot greener and as quick as a car.