Many cutdowns have unneeded parts removed to improve power-to-weight ratio. Typically the front mudguards, leg shields, floors, rear section and side panels are removed. Cutting away body parts is the easiest with Lambretta scooters, because they are built on a tubular frame, which means that the body parts do not have a structural role. Vespa scooters, on the other hand, are usually built with a unibody design, so the body panels give the bike its structure. This means that when Vespas are cut down, they cannot be made as bare-bones as a Lambretta. The body panels of a Vespa are modified by slimming them down or giving them a different shape, in such a way that the structural soundness of the bike is not compromised.