handling

I have a 16" rear wheel with drum brakes on my 83 special. Its my understanding I can swap this out with an 18" with drum brakes as well, direct swap. Is there any adverse effects to handling if i do this? I dont care so much about straight line stability (which I believe my 16" 130/90/16 tire...

I've notice a peculiar thing with my bike. If I'm riding with no hands(just for fun/testing) my handlebars wobble quite violently BUT only at speeds around 45. Any speed faster than 50 no wobble, same with under 40. Weirdest thing. I'm not sure if this is a steering head bearing issue, an...