In respoonse to e-ritchie's and Dave Tesch's comments (I have no idea how to bracket) I'll throw in one oddity. At 6-2, 185 lbs currently, and 168 when racing 25 years ago, I have never had any frames shimmy until I tried the compact road frame geometry guys. All three were ultra-light aluminum. All three were supposedly my size, one by a builder who has built several standard geometry frames for me which ride better-than-fine. All three frames when set up for my position, with donut holder just out of reach, had me forward enough that my eyes, when looking straight down while in the drops, were in front, by about a cm., of the front axle. With standard geometry frames, the plumb line from eyes is about 2-4 cms behind the axle. All three frames shimmied extensively at high speeds on rough roads, but nowhere else. Being a nervous sort, and not having this problem on any other bikes, I gave them away to some local junior racers, who love them, and report no shimmy.
I have no idea what this means in the shimmy world, but simply throw this out for comment.
Charlie Shafer
Madison, Connecticut