Front tyres worn flat across the centre of the tread can cause or contribute to head shake. I understand what happens is the tyre rides up on 1 edge of the flat section, then "falls" back to the low middle section and up onto the other edge. This phenomenon continues which is the head shake. Think of rolling the spare tyre for your car along in front of you. All is stable until it starts to weave slightly, then it just weaves further and further off the straight line. This is why new tyres can cure it.
Update to an old thread: As you can see from our photo we’ve always carried the luggage on our Strada. The additional weight may have saved us from dealing with head shake issues. However, contrary to other assertions of weak design issues, my 09 KTM Super Enduro was downright scary at 65mph. I had to put a Scotts steering damper on it after only a few hundred miles from new to make it rideable at high speed. The dealer just said many KTMs need dampers to feel comfortable over 65 mph. The feeling of instability is not uncommon when dual sports are ridden at high speed.
I have found on my Terra that when i get some headshake at 100kph+ if I lock the throttle on so that I don't need to hold the bars, and I realise my grip on the bars, the shake will go away almost completely. This leads me to believe that it's not just caused by buffetting from wind, or screen, or handguards, or worn tyres, but is induced by the rider, probably because I'm gripping the bars too tightly.
I had head shake since I purchased this bike. The last time I changed tires, I paid particular attention to the rear wheel alignment. I got that rear tire EXACTLY in the center of the swing arm. No more headshake.
I had a very nervous TR, particularly above 100kph. Increased the front tire pressure which helped a lot and also dropped the forks from 2 1/2 lines showing to 1 line showing on the fork leg and this helped to settle her down. No more headshake while changing gears!
