TIL about a 2,000 lb "manhole cover" (big armored plate they welded on the end of a pipe to contain (HA!) the explosion) that got launched into the atmosphere in 1957 by a nuclear explosion test, leaving ground at 150,000 mph (220,000 fps). Spoiler: it probably vaporized.
It could be based on speed rather than mass. Above 5-10 mph or so, you turn a motorcycle with pretty much total countersteering, forcefully pushing forward on the inside hand grip to get the motorcycle to lean over. The faster you're going, the further you need to lean the motorcycle.
Glad to see the twist at the end - great story!