Does anyone have any experience with center stand dollies such as Turn-a-bike or Wunderlich? They look very useful for my tight garage, but I am concerned with stability.
Why not just follow BMW's own advice as given in this video? (Right at the 1:00 minute point.)
Here's the link, and yes, you're right about what I'm thinking of: http://www.vintagebmw.org/v7/node/6918
Sorry, no experience with those centerstand dollies.
I've seen these dollies demonstrated at rallys, most recently at the MOA National in Bloomsburg. The guy had a Japanese bike and was easily moving it around with light pushes. I think they're relatively stable but extreme pushing so high on the bike could be unsettling. But think about it...if you push sideways on the bike while on the centerstand on the garage floor, the reaction will be to tip the bike over. But if you push on the side of the bike while on a dolly, the first reaction of the system is to slide because of the lower friction due to the wheels or sliding surface. My guess is that it would take a rather quick force to tip the bike before it would slide or turn.
My only concern for these systems is how much more you have to lift the bike onto the centerstand because the dolly is 5-10mm further off the floor. You now have to lift the bike that much more.
If you can't pivot the bike ala the video because of room, how will a dolly be any different???
The dollies have caster wheels and can move in any direction, with the bike in any orientation. That makes it easy to stack the bikes up cheek by jowl, if each bike were on a dolly.