I always indicate right because if i did not then there could be ambiguity in my intent, percieved by road users approaching from Studley Road (3).
The 12 o'clock rule would also apply (as taught by my driving instructor, many moons ago!)
Also being a biker, I indicate right (which you correctly state could be percieved to be the intention to come back on ones self) because it would give vehicles entering from Studley Road pause to consider my actions, whether that would be taking the exit or U turning. They would not enter the roundabout in either situation! Which they could do if I did not indicate until ready to exit.
P.S. Something I have noticed in my driving experience in North Yorkshire over the last 10 years is the lack of indicator use! It is extremely dangerous, especially to motorcycles. I can only attribute this to "tractor rules" being applied!
Have you ever been subjected to the famous Yorkshire impatience? Due to the lack of visbility between roads 2 & 3 on the diagram, there are always vehicles entering the roundabout when perhaps they should not!