It is for these reasons that I limited the test to the two types of deflection discussed. Limiting this test to measuring just front triangle and rear triangle lateral stiffness means that the few beam style or other non-diamond frames I tested may flex in ways that I did not measure. An example of such flex might be the movement of the top of the rear wheel from side to side on frames without seat stays, or lateral seat movement in the case of beam frames, etc. I ignored any vertical loads on the frame, as I believe a traditional diamond frame resists such loads easily due to its truss design in the vertical plane. It should also be noted that this test measures deflection directly, not stiffness, but the two are related.
Stiffness is the mathematical inverse of deflection.
At first I measured a few frames, including some steel frames with various brands and diameters of tubing, and several of Bill Holland's oversized diameter titanium frames with different tubing sizes. Right away we could tell that the titanium frames Bill was making at the time were consistently stiffer than standard steel frames in the front triangle, and slightly more flexible in the rear triangle. But when we added the front and rear deflections together for each frame, we found that the total stiffness on most of the titanium frames was higher than that of the baseline steel frames. We thought before the test that the frames were stiff, and now we had the numbers to show it. Still, the fact that some customers felt their Holland titanium frames had too much flex puzzled us for a day or so.