kev125
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RE: Tankslapper.
(06-01-2015, 02:11 PM)SILJA Wrote: Can anyone explain from where the word tankslapper comes? As far as I know it's a front wheel wobble. That hasn't too much to do with the tank. So, what's the history?
The tank becomes involved when the wobble is so bad that your handle bars cause your hands to hit/slap the tank
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06-01-2015, 02:31 PM |
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dommyman
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RE: Tankslapper.
(06-01-2015, 05:14 PM)Amsterdam Wrote: (06-01-2015, 02:38 PM)Alfie Noakes Wrote: It's basically the whole bike "going into one", very violently shaking side to side, lock to lock, front to back with the rider's legs and arms slapping the tank with feet off pegs sometimes, they are truly terrifying, often go on for long enough for you to think "this is it" and start without any notice or warning, usually at higher speeds where the bike is skimming the tarmac and in the worst scenario the rider can be spat off the bike, closest I came was dragged over the front of the bike looking at the front number plate then it sorted itself out and I wobbled on .. smell it ? I was sat in it .. Not much you can do with a proper slapper apart from hang on haha.
...front number plate...?? there isn't any!
You're showing your tender years here Amsterdam, front number plates in the UK were only abolished in the 80's.
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06-01-2015, 05:32 PM |
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Amsterdam
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RE: Tankslapper.
(06-01-2015, 05:32 PM)dommyman Wrote: (06-01-2015, 05:14 PM)Amsterdam Wrote: (06-01-2015, 02:38 PM)Alfie Noakes Wrote: It's basically the whole bike "going into one", very violently shaking side to side, lock to lock, front to back with the rider's legs and arms slapping the tank with feet off pegs sometimes, they are truly terrifying, often go on for long enough for you to think "this is it" and start without any notice or warning, usually at higher speeds where the bike is skimming the tarmac and in the worst scenario the rider can be spat off the bike, closest I came was dragged over the front of the bike looking at the front number plate then it sorted itself out and I wobbled on .. smell it ? I was sat in it .. Not much you can do with a proper slapper apart from hang on haha.
...front number plate...?? there isn't any!
You're showing your tender years here Amsterdam, front number plates in the UK were only abolished in the 80's.
Hang on ... tender years! haha, I quite like that one!
We never had them at all, not that I've seen... indeed, probably... only just ... tender!!!
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07-01-2015, 09:00 AM |
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Malcolm
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RE: Tankslapper.
The Explanation - In two-wheeled vehicles
Wobble or shimmy begins when some otherwise minor irregularity accelerates the wheel to one side. The restoring force is applied in phase with the progress of the irregularity, and the wheel turns to the other side where the process is repeated. If there is insufficient damping in the steering the oscillation will increase until system failure. The oscillation frequency can be changed by changing the forward speed, making the bike stiffer or lighter, or increasing the stiffness of the steering, of which the rider is a main component. While wobble or shimmy can be easily remedied by adjusting speed, position, or grip on the handlebar, it can be fatal if left uncontrolled.
Since shimmy frequency is independent of bike speed, gyroscopic effects "are clearly not essential to the phenomenon."The top five influences on wobble have been found to be lateral stiffness of the front tire, steering damper, height of bike center of mass, distance of bike center of mass from rear wheel, and cornering stiffness of the front tire.
An academic paper that investigated wobble through physical experimentation and computer modeling concludes: "the influence on wobble mode of front tire characteristics, front frame inertia and chassis stiffness were shown. In particular, it shows that [by] increasing front tire inflation, chassis stiffness, and front frame inertia about steering axis and decreasing sideslip stiffness of front tire, wobble mode damping is improved, promoting vehicle stability."
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07-01-2015, 09:06 AM |
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desmophile
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RE: Tankslapper.
At my first Manx I was heading down the Sulby Straight, pre resurfacing, at a good rate of knots when my Ducati went into a massive tank slapper, something it had never done before or since.
It was obviously only going to end one way when a quote from Ray Knight popped into my head re tankslappers 'stamp on the back brake'.
Excellent advice Ray, it worked. If only you had thought to add that it would be wise to pump the front brake to get the pads back in contact with the disc.
That years Manx ended in a rose bush in the front garden of the house at the end of the straight, after my first enthusiatic application of the brakes resulted in the lever coming back to the bars, as did the second and third.
On the bright side, the Ginger Hall were extremely welcoming, providing an ice bucket for my rapidly swelling wrist and several pints of bitter, for medicinal purposes only you understand.
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08-01-2015, 02:44 PM |
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