Originally Posted by
no rules
I would second just use split pipe insulation for the bike frame. Works great. Easy to modify. Reusable. Cheap. Definitely use bubble wrap for the real derailleur.
Check at a few bike shops--a common axle protector for derailleur bikes clips around the axle just to the right of the cassette, and is zip tied/taped/tied to the derailleur housing, after the derailleur is shifted/placed into the lowest gear. It has a large, buttressed piece of plastic that creates a flat surface for the box to lean against.