Motorcycle collecting - usually this type is combined with car collecting, so it is not uncommon to see motorcycle and car museums together. The scheme here is the same as in collecting cars.
People collect retro motorcycles, trying to recreate exact copies of the equipment; they put them up at auctions, inspections, competitions and in museums.
Motorcycles that operated during World War II are in demand, because it was then that motorcycles that were strong and completely different from other ones were made.
For example, these include the BMW R35, the three-wheeled Zundapp KS 750 and others.