Diamond Frame

In a diamond frame the frame tubes run from the steering head to the swingarm pivot above the engine, but there are no tubes under the engine. Instead, the engine is bolted in as a stressed member and completes the structure. Seen from the side, the frame and engine form a rough diamond shape.

The design saves weight and makes the engine easy to reach, so it is common on single-cylinder road bikes, many small commuters and some classic models. Cradle frames, in contrast, wrap tubes underneath the engine.

Because the engine carries frame loads, its mounting bolts are structural: tighten them to the specified torque and never ride with any missing.