I know this has been hashed out before, but please bear with me. I currently own a Univega Modo Volare (Thron steel). The bike feels plenty stable at normal cruising speeds. 49 mph used to be the magic number ... hit that and the wobble began. Soon that barrier became 46. Now it is 40. I have tried different positioning on the bike (weight forward, weight backward, off the saddle, on the saddle). The wobble isn't some mildly disturbing annoyance, but more akin to "bucking". Imagine your rear tire catastrophically deflating. The rear of the bike goes completely loose at speeds over 40. God forbid I have to corner. That feels like the BB is cantering. Could my frame be "loosening" up. I know this sounds ridiculous, but I can't come up with any other explanation. I have a Bianchi Limited from '86 that descends steady as a rock (50+ with NO wobble). I have been assured by my LBS that my Campy Proton wheels are tensioned to spec and my tires (Conti Ultra 2000's) are inflated properly. I understand why speed wobble happens, but no one can explain to me why that speed threshold continues to decrease.