head shake

[sewerat919]

I was recently commuting to work in the morning on I-580 w.b. going through central Livermore when I hit a series of large potholes that caused a bad tank slapper and I went down.
I came out of the situation without a scratch, thanx to my Aerostitch one - piece but, my bike was totaled. When the tank slapper started to happen, it really shocked me, the front end seemed to flutter back and forth at amazing speed, going all the way to the stops!! Being really loose on the bars already, I just
stayed away from the bakes and stayed into the throttle just to see it get worse. I've been asking around for advice about how to control such a situation and have'nt got any clear anwsers on the subject, just a lot of contradictory information. Does anybody have any good "realistic" advice on how to handle head shake??
Please relpy, I would appreciate it!!!!.......Thanx!!!

 

[Wrong Way]

Sorry to hear about your bike but glad you are OK. When the bike is shaking that bad it is impossible to stop the bike from shaking. You basically have to ride it out.

I am going to guess that the whole bike was jumping side to side. When you can hear the tires chirping it is a good indication that the rear tire is moving too. Adding throttle in this case could induce more side to side action. I would have tried to keep a neutral input.

When the bike is jumping around like that it is very difficult to do anything that the bike will consider neutral. The reason being that the bike is moving so quickly you can not act in time to counter its movement. You can’t time adding throttle and you can’t time holding the bars still.

The only movement you can predict is the movement forward. I would try to allow the bike to move around underneath you and try to encourage a steady pace forward with the throttle. A tank slapper is kind of like starting but not finishing a whole series of high-sides in a row. You need to be up on the pegs and ready to separate from the bike.

If the wheels stop chirping and the pegs feel more stable you might try to climb back onto the bike and go for rolling on the throttle. In a tank slapper your rear wheel will move side to side and behave similarly to the front. Loading the back too soon would be like using the front brake during head shake.

So did this happen just west of Vasco Rd. in the number three lane? I would suggest getting pictures of the road and trying to get some money for your bike from Cal Trans. I have never done it myself, but there may be some other BARFers that can help advise you on how to go about it.

 

[sewerat919]

Thank you for the information. It sounds very reasonable and gives me a lot to think about. The location of the accident was a 1/2 mile east of N. Livermore Ave. exit in the #4 lane, obviously the lane that is subjected to the abuses of heavy commercial traffic.

The CHP Officer and I looked to the lane for the cause of the incident and found a series of potholes, cracks and, depressions. Some of the potholes had all the road base washed away from them and, had nothing but mud in their centers. Basically the officer told me that I rode into a potato field.

Maybe avoiding those truck lanes might be a piece of the puzzle, but looking for all the imperfections in the road while riding will cause a lot more problems than tank slappers.

I've been online at a Cal - Trans web site to see how you would go about filing a claim. Advice from other BARFers would help greatly! Like the CHP officer told me, "Cal - Trans is like a big ship and it takes a long time to turn it in the right direction, so don't hold your breath!"

 

[edmo]

It sucks that you went down, but it's great to hear that you are ok.

Steering Stabilizers or "Dampers" such as those made by GPR, Scott, and Ohlins are designed to moderate those rapid bar movements. I don't see why anyone would ride a bike without one as they're relatively cheap insurance.

 

[Outta Control]

I think you just answered your question. It seems that the initial contact with the first pothole started a chain reaction of events that left the tire trying to correct itself through a series of road imperfections. If you have not impacted the pothole then has the possibility of avoiding this chain reaction to occur. I also believe that a short raked motorcycle is more proned to have a stronger, violent head shake as opposed to a longer rake. I've actually experience and experimented this with my BMW. I've gone through very large potholes which I have sensed a large headshake but in less than a second the shaking stopped. Initially at the point of impact I felt that I knew that was a hard hit and knew it was going to shake the bars but was surprised at the results so within the next week I tried to induce a handle bar shake by turning on the cruise control and hitting the right or left handle bars with a good amount of force. I started with a light push and then graduated into a quick shove. And it corrected itself. Now I am not 100% sure if weight or wheelbase was a factor but I do know that the measured rake angles made a difference.

 

[afm199]

A steering damper would have helped. Severe tankslappers are not always "saveable." I hit a pothole on Tomales Rd on an uphill stretch, riding my short rear high NT650, hard on the gas. I went into instant headshake and got spit off about one second later. The guy behind me said :"Suddenly you were fourteen feet in the air upside down." I did not even have time to think.

 

[sewerat919]

I'm definitely getting another bike after the insurance cuts me a check for what the bike was worth. A steering damper might be an option to lessen the severity of a bad shake. I'll certainly look at getting one for the new ride, along with some better riding techniques to handle that kind of situation. thanx!!