Furniture pads work great & fairly cheap at Harbor Freight. But I've spent over 25 years in the moving industry, many loading/unloading trucks. I drape one over every other bike when hauling a truckload & make sure pedals align in the large triangle of the frame & keep 'em tight to limit movement. Alternating direction helps. The pads are also useful for picnics, camping, dog bed, emergency blanket, and protecting furniture. Handy things to have!
Preferred method: Removal of handlebar & pedals makes it much easier & much less chance of damage if possible.