When designing motorcycle frames, some manufacturers prefer to use the engine as a stressed member.?
An engine can provide the necessary degree of stiffness, using it as a stressed member makes a good deal of sense, KTM, BMW, Suzuki, Honda, Yamaha, Kawasaki, Buell and Ducati, all use the engine as a part of the frame in current or recent models, the remaining subframes can be lighter tubular construction. Many manufacturers seem stuck in the mindset of a developed bicycle frame surrounding an engine, and they can make them successful, but it seems unnecessary except as a saving in R&D and for ease of creating modular ranges.
