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Tank slapping and bung chain..OMG!!

Discussion in 'New Riders and Riding Tips' started by Whippet, Mar 2, 2008.

  1. There I was coming home from a great ride with lovely Robsalvv. Leaving Dalesford and tootling along at a comfortable cruisy speed on a nice stretch of road. I noticed alot of shadowing that made it difficult to see the road surface properly.

    Before I knew what happened, I hit a bump and my perfect day turned pear shaped. I lost complete control of the bars - which I now know as tank slapping. All I could do was hang on and pray for the best. That was the closest I've ever felt to coming off - OMG it gave me a fright.

    Once I regained control (thankyou God) and my heart started beating again I realised I had lost all power...my chain had come off :?

    Luckily for me my white knight wasn't far away. Rob went into action mode and fixed my chain...and tightened it :oops: whilst bringing to my attention the importance of regular chain maintenance and my need for a new chain and sprockets :( ....a lesson learnt..the hard way :roll:

    So what I'm perplexed about is how the tank slapping happened. I was riding in a straight line and I hit a bump like any other bump in the road. I'd like to understand what caused it so that I never have a fright like that again.

    Any thoughts?

    Cheers Jen :)
  2. Hi Jen,

    Glad nothing bad came of it .. this is copied from another site here .. http://tinyurl.com/ypxkoy

    I've had it happen to me .. very scarey indeed..

    The “tankslapper†is a very frightening experience. Usually occuring when accelerating hard over bumpy pavement, a tankslapper ensues when the front tire becomes airborne, then regains traction outside the rear tire’s alignment. The resulting deflection bounces the tire off to one side, followed by another bounce in the opposite direction as it contacts the pavement again. Unless the bike’s steering geometry is able to damp out the deflections quickly, the resulting oscillations from the front tire as it bounces back and forth will swiftly gain in strength, causing the bars to swap from side to side with increasing ferocity. The oscillations can be violent enough to rip the bars out of your hands, and fling your feet off the pegs. You can guess what happens next.

  3. The is a thread on tank slappers...perhaps you answer is there?

    But usually means loose head stem bearings?,...or worn front tyre? or too fast for the conditions? ie your bike is not up to it!

    Truth must be told.

  4. Thanks Tim :)

    That's a good link.

    I wonder if it's common amongst VTRs?

    Grey Gentry...I think I'll have a word to my mechanic. Thanks for the input.

  5. Unless you're getting constant headshake over rough roads and at higher speeds, I doubt there's anything wrong with your bike or setup. Hitting a pothole like that or landing a wheelie a bit crossed up will get most bikes without a steering damper tankslapping, especially when you're not used to a bit of headshake and hold on TIGHT. That really get's it going.
  6. :eek: Glad you're ok, Jen! Sounds like you rescued it nicely :applause: How did you go pulling over with no chain? You must have had plenty of time/space to slow down?... and not panicked? The shadows can certainly hide some nasties.
  7. no probs Jen ..

    Mine was totally self inflicted and just plain stupid .. lesson learnt now tho.. The VTR250 is truly a forgiving bike.

    Was travelling along a road I wasn't familar with over Tulla way (Thurs Mystery ride).. coming up a slight hill, and overtaking a car. Only to realize at the top there was a slight left bend, immediatley followed by a round-a-bout. Was too hot coming to the round-a-bout, and being in a left turn .. was kinda stuffed to effectivley rub off speed. Hit the back brake, locked up and bike got sideways on me .. seeing an imminent low side, released the back brake, as a result back wheel gaining traction quickly, and somehow got to some where near the same tract as the front, but obviously not totally, as I then went into the tankslapper. My days riding MX bikes come into its own then .. by the time the bike was back under control, after letting it do its own thing, and just trying to relax, I was about 2mtrs from the curb on the roundabout .. No chance to stop, prolly still doing around 40km's. Clouldn't turn in time, so no option but to go over.. thank god there wasn't any barriers .. it must have been the worlds bumpiest pc of grass in melbourne. However, managed to keep it up and come to stop to let my heart slow down a bit .. riders behind were sure I was going down, but somehow managed to come through both little mini adventures
  8. Thanks for the kudos Jen :)

    Kudos to you for pulling that clutch in quickly enough before you did some serious damage!

    :oops: I didn't realise we were riding in the licence saving zone... I swear I thought we were cruisin.

    That wasn't just one bump, that was a series of rotten bumps. The 9 ate them up and spat them out but not without some violent vibrations. If I had any inkling your bike would have reacted so poorly I would have tried to warn you somehow.

    Very very VERY glad things didn't go pear shaped.

    Now about that chain... This is the first time I've seen a motorcycle chain derail off the sprocket under load. I could see that the chain needed some maintenance but I've seen far worse so didn't think that what happened today was possible.

    But those bumps were seriously farked! And unfortunately the VTR didn't react well to them, plus that tank slapper thrown in for good measure... the violent whipping would have left that worn chain without much of a chance.

    It didn't take long to get you up and running again... pity I didn't do as good a job as I had intended... er... um... :oops: ...rear wheel axles need to be retightened after chain adjustment... lucky I picked that up a kilometre down the road and we did a take 2 on the roadside maintenance... :roll: @ myself.
  9. Thanks love :)

    Fortunately it was a very quiet road so pulling over wasn't a problem...it was quite easy really because I just went slower and slower :shock: :LOL:

    As for the panicking - I didn't have time to panic. It managed to correct itself - miraculously. Once I'd stopped, I was more worried about getting the chain back on then the tank slapping. Looking back now (and having read some others not so lucky experiences) I'm fortunate I didn't know what was happening bc I would have been more worried about coming off. I imagine that's when you go home to clean your draggins :shock:

    I was lucky indeed!
  10. Hey Rob,

    You did a brilliant job getting me back on my bike

    You are an :angel:
  11. Glad you made it through your experience Tim!... Your story though, is the exact reason I always bang on about not going for the rear brake in a panic... it has too many things that can go wrong.

    Just for the record, Jen handled herself calmly and with utter aplomb. Once we were done with the chain, she was more worried about my greasy fingers than the experience she just went through. She rode off like nothing had happened. :)

    ... erm... taa darlin :)
  12. Wow Tim that must have shaken you up. That could have easily ended in tears.
  13. Sorry to hear Jen! :shock: Glad you came out OK and that Rob was there for you :cool: He's not a bad bloke is he :wink: :LOL:
  14. Thanks Dougz :)

    That Rob isn't bad at all :wink:
  15. Tank slappers happen now and then, but a chain leaping off the sprocket, that's way crazy. I'd brick meself.

    We'll have to get you down to a Wednesday spanner night (tm) soon and show you how to tweak that sucka so it stays put! ;)
  16. Your a cracker :LOL:

    I'd be interested Loz but I work Wed nights :(

    If you have any other time free i'd be happy to do a trade wit ya
  17. Couldn't agree more Rob, but yeah.. I did panic a bit .. not sure what else I could have done .. seeing there could have been cars coming from the left .. major lesson learnt .. know the roads yr riding before riding anywhere above 50% !!

    No doubt !! thankfully it didn't.

    For the record .. it was this roundabout .. http://tinyurl.com/ywhn2s coming from the left on Airport drive.
  18. who needs plenty of room to stop, with no chain? the brakes still do the job.

    good to hear you recovered from the incident without further incident, Jen. and you too Tim. you and overshooting left handers, mate, you worry me :p
  19. They certainly do! However, with no chain, if I understand correctly, there's no engine braking. It'd be like riding with the clutch in... free-rolling, which would make it a little more precarious for Jen.
  20. Jen!...You might not think it right now, but THAT was a GREAT experience...albeit very scary and I'm very relieved that you are ok..phew!
    A great experience because you will never forget it and you will draw on it from time to time in the future.

    As Rob suggests, the VTR probably got out of shape on the bumps, and went into a slapper...either that or the chain caught on the swing arm momentarily when it came off, or jammed bewtween the wheel somewhere, and locked up your rear-end, unsettling the bike just at the wrong time - enough to cause you the slapper.

    Either way...there is only one way out of them...lose arms and in this particular case, some good luck.

    Now...to the most important question of all...What the hell were you doing riding around with a shagged chain, when you have Rob to fix it for you????... :p :p :p :LOL: :LOL: :LOL:

    Maybe you could do with a fork oil change and possibly a slightly heavier oil as well...just to help the front-end along a bit. :) (Hi Rob) :p