I have an '04 Litespeed Siena. It used to get twitchy around 75kms/hr and then the integrated headset went south. Got a new, traditional style headset last summer through warranty.
So... yesterday I was going down a nice hill at around 65kms/hr and I got a speed wobble strong enough that it was a bit scary. I want to go fast. I want my bike to go fast. With the bars unweighted (i.e. sitting back and letting go) I've gotten a speed wobble as low as 45kms/hr.
Headset is adjusted correctly
Wheel bearings are adjusted correctly
Tires are on straight and the wheels are true.
Any ideas? I've got the stock carbon forks. Is there a chance they're too flexy? (I weigh ~160lbs)
What about the head tube? Think that's screwed up somehow?
Thanks for any help!