thx Pete
Here is a diagram I slapped together looking at a tall streamlined bike as a "wing" of sorts from the top, don't know if it is entirely accurate and haven't figured out if the wheels make a significant gyroscopic stabilizing contribution at higher speeds or not either, so take w/salt.
re: diagram above, I sort of think it is not accurate in this case as you approach 90 degrees. If you had just a sidewind pushing on the area, you would expect some force to be created, dunno.