I have seen issues with tapered bearing before causing some strange issues....not properly seated in the frame or could not be properly seated due to them going in slightly sideways causing some aluminum to get cut out and wedged beneath the bearing seat causing it to be off axis slightly.
Hmm, I don't think
this is likely; I have some decent experience of installing tapered head bearings in the past, and I was quite careful with their bottoming squarely. Also, this ..warble.. has been around for quite a while before I swapped the head bearings out. The old ball assembly WAS quite heavily notched, but when I changed it over, the Warble did not change. (a big disappointment!)
Aero dynamics can play a big part. My bike with upright bars can get a bit of wiggle in turbulent rough air when in the vicinity of large trucks.
YES! This is a major symptom! At most lower speeds I don't notice this problem that much, but get up to 60 or more, it becomes more obvious, especially with wind turbulence or road surface flaws.
I do have the CNC tubular handlebar conversion, AND a low-slung Corbin seat, which puts me in a weird squat position sort of like a dog with it's paws on the table! I'm working on lowering those pegs... But I AM a pretty large load: 6'1" and 270 pounds. I did try going back to the stock clamp and clip-ons... that didn't help.
Under sprung rear can cause issues also because of load transfer to the rear. The other way around also. Wow, 375 lbs/in spring! How much sag on and then off the bike do you have? How is the front sprung? How is the chassis geometry in comparison to stock?
I'm not sure WHAT spring rate I should be using; I bought a Penske 8795 used...sent it to Penske for rebuild.. it had a 400 lb spring that was like a rock, so one of you kind folks swapped me for a 375 (was that YOU, Mike?) .. which STILL seems too stiff. I'm 270 pounds and the only way I can get 40mm of sag in the back is to have the preload almost all the way out.
In front I have Sonic springs at 1.0kg as I remember... with a Gold Valve kit.. I think running 5 Wt (maybe 7.5 I'd have to check the notes). I get about 25-30mm sag up front.
Could this be an overly-stiff spring rate out back? Or, is it possible the shock length is too high? It's been a while...but I THINK it was the same as stock when I first installed it, pretty sure I would have checked that carefully three years ago.
Thanks for the help, guys. I really like my SV, but this Warble is drilling me!