Knowing which part fits which model is a genuinely hard data problem that customers struggle with constantly. A fitment database is the most defensible business under this name. The market covers both bicycles and motorcycles: parts, accessories, upgrades, servicing, and a used market with real depth. Riders in both worlds modify continuously and spend accordingly. Aftermarket is the trade’s own word, carrying the full infrastructure of parts suppliers, dealers, workshops, and the distinction between original equipment and everything else.