@Myrddin Wild
I just reread your first post in this thread and you were talking about getting a backrest because over long rides your back gets a bit sore. The reason for your soreness is largely due to the seating position.
Getting a backrest might not solve your problem and may, in fact, create new ones. I found when I had a driver's backrest I would bump against it. It wasn't long before my back started getting tender from repeated contact with the backrest. I pulled it off after a few weeks.
I know it seems like I'm bashing cruisers in this thread, and I am to some degree, but really it's just about sharing information on one of my favourite hobbies.