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Old 09-14-2012, 11:17 AM   #5565
Pantah
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Joined: Oct 2004
Location: India Wharf
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Quote:
Originally Posted by tattewell View Post
Clearly we don't all know it, I have never experienced headshake on my 690... interesting though.
I think Barman is referring to the steering wobble that happens at high speeds. I think it is a shape-of-the-tire thing, combined with freeway turbulence grabbing the rider's shoulders.

My old 950 had that wobble above 95mph when I used TKC80 front tires. They have a round cross section, as opposed to the more triangular front tires like the Scorpions or Mefo's.

My 12 690R can also have that wobble above 75mph so I added a damper that works well enough up to about 90mph. I still have my MT21 front, but I am pretty sure if I replaced it with a more triangula tire, it would be more stable at higher speeds. I like the tire, though, and I don't cruise any faster than about 80mph anyway.

In my experience a 'headshake' is a suspension or geometry issue generated by bottoming the forks through ruts, or an improper set-up on a road race bike. It usually surfaces under power on corner exit or an esses where the racer flipflops the bike. They can degenerate to a full blown tank slapper in a flash. I'm not sure the 690 wobble will turn into a tankslapper, but I will admit that it feels like I am loosing directional control if I don't stop it somehow.
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