Over The Hill said:
OS maps show right of way on private land. I think it is landranger maps. Multmap.com have an OS button so it is on line and free. Right of way are in green dashed lines I think.
I think you can have a gate on farmland across both private and adopted roads. Right of way may just exist on foot. I am not sure if a bike is deemed to be different to a person.
Rights of way don't exist in Scotland in the same way as in England, and therefore aren't shown on OS maps of Scotland.
Also, in Scotland a bike is viewed as an "aid to pedestrianism" and can be taken anywhere you can walk (roadside pavement probably excepted, and subject to not causing damage).
I'd go by the Access Code mentioned above, and reckon it was OK to use in the absence of keep out signs or locks.