my partner and i share a 2001 Speed 7 for BART trips into the city. Lately it had developed quite a floppy handlebar stem--about 1" of play, rather alarming, especially when starting off. Yesterday before an errand-run, I cleaned off the surfaces where it clamps together, and applied one 1.5" diameter felt furniture pad, cut in half, to the outer edges of the bottom of the joint. Now it is very tight and rides like it was brand new.

I think a proper rubber gasket glued on with loc-tite would be a more permanent solution. This works great for the time being, and it made my visit to San Francisco a speedy pleasure.