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+--- Thread: Tankslapper. (/showthread.php?tid=18554)
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Tankslapper. - SILJA - 06-01-2015
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?
RE: Tankslapper. - c iom tt - 06-01-2015
For some of us that have had a real tank slapper, when the forks are going lock to lock so fast that it sprains you wrists (as in my case) the other noise is the clip-ons banging on the tank.
RE: Tankslapper. - kev125 - 06-01-2015
(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
RE: Tankslapper. - Alfie Noakes - 06-01-2015
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.
RE: Tankslapper. - c iom tt - 06-01-2015
And for a visual acount of a tank slapper, this is Paul Orrit getting a ' 10 from Len' going down Bray Hill.
https://www.youtube.com/watch?v=XiKmPFo6xNA
RE: Tankslapper. - Amsterdam - 06-01-2015
(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!
RE: Tankslapper. - dommyman - 06-01-2015
(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.
RE: Tankslapper. - Alfie Noakes - 06-01-2015
The front number plate on a race bike .. at the front of the bike with a number on it ;o)
RE: Tankslapper. - Amsterdam - 06-01-2015
(06-01-2015, 06:06 PM)Alfie Noakes Wrote: The front number plate on a race bike .. at the front of the bike with a number on it ;o)
ow right, I see... thought about registration number plate, us lot out here used to happily wave at speed cameras in front of us, suppose the Brittish used to do the same. Unfortunately nowadays, you don't really see them they are more hidden, don't flash a light etc.
RE: Tankslapper. - SILJA - 07-01-2015
Thank you guys. I think I've got it now!
RE: Tankslapper. - Amsterdam - 07-01-2015
(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!!!
RE: Tankslapper. - Malcolm - 07-01-2015
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."
RE: Tankslapper. - Alfie Noakes - 07-01-2015
If it's properly gone in to one you have to hope it sorts itself out - you can't do anything else apart from hang on, thankfully most of 'em do but they can go on for what seems like ages. A very basic example is a shopping trolley wheel - as you push the trolley the wheels reach a speed / frequency and they'll shake from side to side.
RE: Tankslapper. - desmophile - 08-01-2015
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.
RE: Tankslapper. - Shooie - 06-02-2015
In my youth, and early days on motorbike, I remember the somewhat older guys telling us young pups tales of tankslappers.. and their advice at the time was... if you got one accelerate out of it.
Hmmmm..
Luckily I never experienced a full-blown tankslapper.. but had more than a few wobbly moments due to front forks being filled with 10% oil and 90% water. Well no one told me that fork seals could fail !!!!!! lol..
RE: Tankslapper. - Steady the Edward - 06-02-2015
All I know about them is if one of my bikes gets one , it will have a for sale sign slapped on it on its return home if it makes it that far ,
.
RE: Tankslapper. - captainsparkledotcom - 06-02-2015
(06-02-2015, 12:07 AM)Shooie Wrote: In my youth, and early days on motorbike, I remember the somewhat older guys telling us young pups tales of tankslappers.. and their advice at the time was... if you got one accelerate out of it.
Hmmmm..
Luckily I never experienced a full-blown tankslapper.. but had more than a few wobbly moments due to front forks being filled with 10% oil and 90% water. Well no one told me that fork seals could fail !!!!!! lol..
That was what I was told, too!
(06-02-2015, 08:26 PM)Steady the Edward Wrote: All I know about them is if one of my bikes gets one , it will have a for sale sign slapped on it on its return home if it makes it that far ,
.
Eddy! New avatar!
Are you going to Ilkley?
RE: Tankslapper. - Alfie Noakes - 07-02-2015
Not sure how you're mean't to accelerate when the bars are smashing themselves against the lockstops and your feet are off the pegs, a proper high speed slapper has you sat there until it sorts itself out or not .. the application of back brake might work but the physics of that will make the bike stand up - ok in a straight line, not with any lean angle involved. Just hang on to her
RE: Tankslapper. - Steady the Edward - 08-02-2015
Sparks whats with the trying to confuse me !! why would I be going to Ilkley moor ba tat ?
yes changed the avatar "with a little help from my friends" as it says in the song , shhhhh Malcolm dont tell ,
.
RE: Tankslapper. - Shooie - 08-02-2015
(06-02-2015, 09:16 PM)captainsparkledotcom Wrote:(06-02-2015, 12:07 AM)Shooie Wrote: In my youth, and early days on motorbike, I remember the somewhat older guys telling us young pups tales of tankslappers.. and their advice at the time was... if you got one accelerate out of it.
Hmmmm..
Luckily I never experienced a full-blown tankslapper.. but had more than a few wobbly moments due to front forks being filled with 10% oil and 90% water. Well no one told me that fork seals could fail !!!!!! lol..
That was what I was told, too!
(06-02-2015, 08:26 PM)Steady the Edward Wrote: All I know about them is if one of my bikes gets one , it will have a for sale sign slapped on it on its return home if it makes it that far ,
.
Eddy! New avatar!
Are you going to Ilkley?
Cap Sparkle.. and we lived to tell the tale
or the "stories" of dering-do tankslappers.