Where is the “Delta” in the Deltabox frame?
There are many different kinds of motorcycle frames and they have different names depending on their shape or construction. For example, a cradle frame “cradles” around the engine while a diamond frame (shaped like a diamond) or backbone frame (like a spine) suspends the engine from the frame. You can typically find the frame type listed on the bike’s specification sheet.
Yamaha’s Deltabox frame design can be classified as a diamond frame, but we call it Deltabox because it embodies a unique Yamaha design philosophy.
The frame achieves excellent torsional rigidity by making the lines connecting the top and bottom of the head pipe*1 to the rear swingarm pivot*2 as straight as possible. The frame was developed based on the idea that the key to good motorcycle performance lay in the balance of the forces concentrated at the head pipe (the front end of the frame), which bears the forces from the front wheel, and the swingarm pivot (the rear end of the frame), which bears the drive force from the rear wheel.
&nbps;It uses a long head pipe, so when seen from the side, the lines form a triangular delta shape andthe cross-section is box-shaped, hence “Deltabox.” The engine is mountedwith a high degree of rigidity, and results in a well-balanced chassis that delivers a ride with responsive handling and greatstability. The frame also has a delta shape when seen from above.
Since 1985, the Deltabox frame design has been used on Yamaha supersport models—regardless of engine displacement—and continually refined over the years. The initial inspiration for the design came from the development of Yamaha’s YZR500 factory racer in the early 1980s for the premier class of the Road Racing World Championship Grand Prix.
For more on the Deltabox frame, see Frame Technology Christened in Salzburg on the Seeds of Creation website.
- *1:The neck part of the frame
- *2:The axis where the swingarm is attached to the frame