Guy Martin - Triumph Rocket Streamliner

[rouse]

I think that weave can also be caused by steering bearings which are set too tight or a steering damper that is set too tight (I believe a small amount of free movement is beneficial).  A bike that is well designed and set up correctly will naturally want to go straight.  But either of the above conditions can cause the rider to have to force the bike into a straight line and may cause him to overcorrect due to the resistance of the steering components, setting up an oscillation.
Tom

I thinking along the same lines as Tom on this.

The problem for sure is not the salt in this case, saying that will only lead to not fixing the problem. They need to take a good look at the entire steering setup on their bike, because something is completely out of wack.
 That said, it could be the simplest thing, say damper to tight, or kingpin "dragging", not enough caster angle, thus not enough trail. I doubt that the steering ratio has much if anything to do with the weave I saw, If anything it looked like he was using way more input (movement) than the standard 1:1 ratio found on normal ride on bike. I rarely use more that 1/8" during a run, ruts and all.

Hopefully they will figure out that the issue is something that is simple and easy to fix. One thing for sure, it needs fixing.

Rouse 

[TheBaron]

To test for the natural frequency of a chassis or even a single part, all one has to do is suspend the item from its balance center (a rope or chain), and then firmly tap the item's with a rubber or leather mallet.... It will vibrate for several seconds at its natural frequency just like a tuning fork...Note, you strike the chassis frame and not any body work or other secondary materials.

Now measuring that frequency is best done with a acceleration transducer system...They can be rented but are pricey as they are scientific/engineering level equipment.

Low cost way that works fine is to use a microphone and any audio recorder to record the "ring".  Garage band shure microphones work fine. Find an electronic guy that has an oscilloscope  and feed the audio recording to the o-scope by hooking the o-scope probe to the speaker leads....You will see the natural frequency as a sine wave on the scope.

AS a sidebar, the 500 two-stroke GP Honda "Big Bang" motors of the "80's" were understood only after another team made  trackside audio recordings of the bike going by and then playing the recording thru an O-scope they could see the uneven firing intervals exactly.

Robert

[stay`tee]

Interesting video,,

 This bike has made "many" +200mph passes since it was first ran in 2013,, I notice that the "weave" is in the mid to high 190mph range, one would assume that had this weave occurred in previous passes thay would have had it corrected by now,, listing to Guys comentry it seems to have caught him by surprise,, I also notice that when he snappes the throttle off, the thing becomes stable,, also, without gloves on he would have improved "feel" input into the steering system, with wearing fireproof (thick) gloves would slow the feel into the steering movement ,,

Question, was this pass the first time that the weave occurred, if so ,is something changed in the geometry, aero of the machine  

[TrickyDicky]

Anyone know whether Guy Martin/Triumph are planning to be back in 2017?

There doesn't appear to be any recent publicity.  The best I can come up with is a quote from November 2016:

Triumph’s Chief Commercial Officer, Paul Stroud, said: “We are 100% committed, as is Guy Martin, to breaking the overall motorcycle land speed record. We are absolutely focussed on going way beyond the record that we set this year of 274.2mph, which we broke during testing in incredibly challenging condition, conditions that held us back from a full top speed attempt. Next summer, we will be back at Bonneville. Weather and conditions permitting, we hope to bring the record home to Triumph for the fifth time in the brand’s history, which would be a record in itself.”

[stay`tee]

Thay are listed as entrants at the Shootout