Self induced Speed Wobble.

[(RIP) Geriatric Germ]

Not a Tank Slapper, but on Sunday, a full stomach and nearly empty fuel tank, quiet B road I Waggled the bars (to see what happens) under controlled conditions at around 80. Result, it felt like the frame, such as it is , was seriously Flexing and that if I had continued would have thrown a real Wobbly. After filling up with fuel, tried it again and the result was remarkably better, (no silly, not as bad a Wobbly), over the years, on various BUM's I have noticed a similar result, empty versus tanked up .
The reason I do this Silly little experiment is that in 1976 on an R90S at about 90 along the Cressage Straight I had the fright of my life and the biggest unprovoked Slapper of all time it was caused by my meanness and non availability of a matching Metzeler rear tyre, so instead of fitting a pair of Conti's I just fitted the mix of old Metz front and new Conti rear. Near disaster. Has any one else noticed the sensative feel of the unladen 12GS or does anyone fancy trying the first part of this diatribe and, if you survive, reporting back.

HEALTH WARNING. Behaviour like this can not be condoned nor recommended, I accept no responsibility for the actions of any person in any way shape or form and I am not insured, nor employed nor do I own any property or have money anywhere, other than my measly State Pension. The 12GS I used was a Demo and not owned by me.

 

[JohnnyBoxer]

Should ride a proper bike and kept your old Adventure, then you'd have been on a lardy GS...............too heavy for a speed wobble

 

[boundless]

HEALTH WARNING. Behaviour like this can not be condoned nor recommended, I accept no responsibility for the actions of any person in any way shape or form and I am not insured, nor employed nor do I own any property or have money anywhere, other than my measly State Pension. The 12GS I used was a Demo and not owned by me.

I think what he means is:-

Don't try this at home, kids!

 

[Schtum]

The reason I do this Silly little experiment is that in 1976 on an R90S at about 90 along the Cressage Straight I had the fright of my life and the biggest unprovoked Slapper of all time it was caused by my meanness and non availability of a matching Metzeler rear tyre, so instead of fitting a pair of Conti's I just fitted the mix of old Metz front and new Conti rear.

Been there, done that. A friend's TT100 shod R75/6 tried to spit me off at 80 mph. It should, of course, not have been fitted with a tyre with such a flexible carcass as the Dunlop had. He never had any trouble with it because he was much heavier than me and just like your full fuel tank, his mass damped out the oscillations. Old air heads were very sensitive to tyre choice and needed ones which were capable of damping out the oscillations of a much too flexible frame.

 

[Dave Price]

.
The reason I do this Silly little experiment is that in 1976 on an R90S at about 90 along the Cressage Straight

Only 90 along the Cressage straight ya wus