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tank slappers

Discussion in 'New Riders and Riding Tips' started by gunnin' it, Dec 31, 2005.

  1. hey guys im new and im wondering what a "tank slapper" is.

    sorry prolly real dumb question lol :cool:

    but yeah could peeps please give me examples of such incidents???

  2. They are like tyre kickers with cars.. you walk around and slap each others bikes like "wow nice scoot mate"


    Its when you get all out of shape and the bars want to rotate back and forth, side to side as the front wheel dives from side to side. This tends to make you hit the tank while you are trying to gain control of it again (usually not if its a bad one)
  3. years ago a mate of mine came off doing 100 km/hr due to tank slapping....

    I'm talkin like 15 years ago so bike technology is way better now, but I've heard it can be pretty scary if it happens
  4. The phrase comes from the action of the bars (especially clip-ons which face downwards and have minimal clearance at the best of times) 'slapping' into the side of the tank as the front end wobbles in a high frequency oscilation from side to side.

    They ain't fun; I hit a series of 'stutter bumps' on the New England Highway back in '79. I was doing dead on 60 mph (100kph approx) and before I knew it the bars 'slapped' backwards and forwards about 6 times in each direction and spat me over the top of the bars and up the road on my side. I slid for aound 50 - 70 metres and got up unharmed, but the bike was a mess.
  5. "back in '79"....woah brings memories of my dad's motorcycle stories lol!

    blah blah blah yamaha 650 blah blah blah kwaka 900 etc lol

    on a serious note,(hornet especially) are bikes today heaps more reliable, better handling, comfortable, fast etc?? cause from what dad says, bikes in the 70's and 80's were pretty shocking! (spesh handling wise)

  6. Funnily enough (wasn't funny at the time, they put me in hospital overnight just in case I'd injured my kidneys with the camera I had in my jacket pocket) as it turned out, the accident was at least partly my fault.

    The bike was only three months old, a Kawasaki 500/4, bright red and how I loved it, but I replaced the standard Japanese rim protectors with a new set of the tyre-of-choice of the day, the Pirelli Phantom. After the crash I was so disillusioned with the bike I sold it back to the dealer who had sold it to me and bought something else.

    He put the standard tyres back on it and tried everything he could to produce the same result on the same bit of road (it was only 3 kays away from his shop.) The bike behaved perfectly and he sold it soon after to a local guy who also never had a similar thing happen. As near as I can guess, the bike's front-end geometry didn't suit the Pirelli Tyre.

    Modern bikes, heck yes, lots better. BUT if I take my hands of the bars on the Hornet at about 50 - 60 kays the front end does shake rather alarmingly......
  7. Bikes vary...

    I can take my hands off the bars on the Moto Guzzi and stand up on the pegs with the cruise control going and ride standing up for as long as I want (and control direction by leaning).

    The ZRX1200R I can take my hands off the bars but I can't maintain any sort of directional control.

    The Diversion 900 I have to keep at least one hand on the bars at all times, if I take 2 off within seconds I get an increasing oscillation of the bars back and forwards which would develop into a tank slapper very quickly if I didn't grab the bars again.
  8. Young Gunnin'....

    it typically happens under power just before the wheel is about to lift (or just as it is touching back down). Personally I think a steering damper is a very wise investment if you bike doesn't already have one.....Hasn't happened yet on my R1 which is a brilliant bike from a chassis/suspension POV - and it has a steering damper...

    Does your dad still ride?

    Ah Hornet - I remember fitting Phantom's to my CB750 - but that was in like 86 or 87 - as you say - they were considered the bee's knees - even that late...

  9. I had a tank slapper at about 120kph which sent me over the handlebars... that was 14 years ago. Not so much scary as unexpected. I was off the bike before I even knew what was going on. I learned later that I probably tensed up my arms, thus transferring the headshake to the back wheel via the rest of my body and that's what caused it to spit me off. Now I'm older and wis^H^H^H older so when it starts I know just to relax and ride it out.
  10. so is this a natural tendency for the front wheel to go side to side and oscillate?

    or does it take some bump from the road usually to set this off?

    more importantly is there any way of preventing this from happening? or knowing its going to happen? cause being thrown off without notice wouldn't be fun
  11. I still ride bikes from that era... Guzzis and Hondas (CX). And they handle great. Some Jap stuff had too much power for the frame to handle, but their mid capacity stuff was fine.

    British and Italian stuff of that era was good handling. Although I'm told not up to the knife-edge standards of todays aly framed sports bikes.

    Also, fast enough.
  12. I'm don't know if it's a natural tendancy for the wheel to want to do that but if you google you'll probably find it's to do with harmonics or oscillations or something..

    a bump in the road will be the usual way to set it off, or just a wide open throttle.. anything which causes the front end to get light..

    steering dampers will stop or reduce tankslappers by not allowing the steering to rapidly change direction.
  13. If it starts on you, take your weight on your feet, lean forward while gripping the tank with your knees and keep your hands lightly on the bars.

    It will usually self-correct.

    Undies may then need your attention.

    Take your weight off one foot ... etc.
  14. In that vid, in the slo-mo replay you can see the bike hit the bump just before the slapper starts
  15. That guy had bigger problems that the bike wanting to slap... as he tells it in the post-stack interview, his shock linkage broke. That's what started it.
  16. As do tyres for a certain bike as Hornet said. My bike with different tyres.

    Stock Dunflops : No worries, hands free riding
    Metlzers: No worries, hands free riding
    Avons: decel wobble from under 100k and NO way I am taking both hands off, even one hand off is unnerving.
    Current Dunflop D205's : No worries, hands free riding
  17. thanx guys.....no dad doesn't still ride but i think he'll be back into it someday....im jus tryin to convince him, so he can take me for pillions lol (i have been hooked by a blast wit my uncle on the back of his ducati 900ss). damn tank slappers look scary...
  18. can i add that tank slappers are scary as hell?
  19. G'day, Ten or so years ago I had a Kawasaki 1000, the model with 16" wheels. It got into a tank slapper big time on a fast sweeper. A tyre guy with us said put a few exta psi in the front, excellent after that, does'nt work on all bikes but