Stressed member

A stressed member is a part that carries structural loads as part of the chassis rather than simply hanging in it. On motorcycles the term usually refers to the engine: the frame is bolted directly to the crankcase and cylinder heads, so the engine itself links front and rear sections and adds stiffness.

This saves weight, reduces the number of frame tubes and allows a more compact layout. Famous examples include many Ducati, BMW and KTM models, and the Vincent motorcycles of the 1940s. Some bikes also use the engine as the mounting point for the swingarm.

Engines used as stressed members must be solid-mounted. When working on such a bike, support the chassis properly before removing engine mounting bolts.