When I got my Royal Star last fall the previous owner had the grips a bit higher than I was use to. I rode the bike like it was, then started playing around with the position.
the handlebars on the stock Royal Star are a good 10" from the triple tree center to the grips. I pulled them down lower for a few days, kept looking at photos of RS bikes on google -they were all over the place from nearly touching the tank to being straight up.
I thought maybe they are suppose to be in line with the angle of the fork - maybe that puts the grips in the center of rotation, so I tried that. They were like mini ape hangers pushed that far forward.
I rode to work the next day and 3 miles down the road both hands were completely numb. I was sitting up straight and comfortable, had a good grip and good control over the bike, but with my hands just that little bit higher I was riding shaking one hand, then the other, to keep the blood flowing, the entire 30 minute ride to work. During lunch I put them back where they are in the garage photos.
The takeaway here: before you spend a lot of money for risers and cable extenders and taller handlebars maybe crank the ones you have up as high as you can. Sometimes the effect is unexpected.