Tankslappers
So, talking to the guys at the bike shop about tank slappers, one person PMing me and asking me about head shake and tank slappers, and another posting to the board and asking about head shake, and then, finally getting a chance to read Road Racing World and seeing fellow California Superbike School instructor, Misit Hurst, has written an article about tank slappers, I can only laugh. Mostly because Misti's tankslapper story was funny - to me at least.
I guess tank slappers are in.
With todays high hp, sharp steering bikes, head shake and the imminent tank slapper is something that's here to stay. The manufacturers know this and are making steering dampers standard on almost every sportbike made.
Even though we have steering dampers, we as riders, need to know what to do so we don't make the situation worse.
First, lets look at what a steering damper does. A steering damper is connected to the forks and the frame. Inside it's a piston surrounded by oil. When the forks move, the piston moves. This movement pushes the oil through a small hole. The size of the hole determines the amount of resistance there is to moving. The size of the hole isn't really changed, a needle shaped rod is moved into or out of the hole thus allowing less or more oil to flow. The damping on your suspension works basically the same way.
When the forks move, the steering damper slows down the rate of movement by redirecting the force to the rear wheel via the frame. The mass of the motorcycle and the larger contact patch or the rear tire generally provide enough resistance to motion of the front wheel to slow the occilation. Basically the force get's absorbed by the bike.
Now what riders typically do when there's head shake is they hold on tighter. This amplifies the occilation because the rider doesn't have the mass or rigidity to effectively stop the front wheel from moving.
When the front wheel moves to the left, the force gets transferred to the rider through his stiff left arm and out through his stiff right arm which turns the wheel more to the left. Trying to hold on harder can lead to broken fingers, wrists, and even just throw you off the bike entirely leaving you to watch your bike suddenly stabilize and go on its merry way without you.
So, what do you do?
1. RELAX THE ARMS. If you're trying to go fast and you get head shake, relax the arms. If it continues to escalate because you're holding on to the throttle too hard, (something I'm guilty of) get off the throttle and relax. If it still gets worse, LET GO of the bars. If that doesn't work, well sorry. I guess that's what destiny is.
2. Get more knowledge. This is only a brief overview. Read Keith Code's explanation of head shake in Twist of the Wrist II. Read Misti's article. Dare I say practice? Sheesh, no. I daren't say that.
3. If you don't have a steering damper, get one. It will help handle the emergency. It won't stop the head shake. If it does, it's probably too stiff.
I was just talking to a racer a few days ago that said he had just exited a turn and was on a straight when he got into a tank slapper. He said he managed to stop the the bars from moving by grabbing on tight. As soon as the front stopped moving the back came around and he crashed.
What do you think happened?