[creed82]

TW friends. I was riding a TW for the first time yesterday (2007 blue/white) with my best friend in southern Arizona. I have ridden motorcycles plenty during my life, and I'm not new to bikes or riding them off-road. We were riding down a FLAT, STRAIGHT, GRADED dirt road with light washboarding. I was cruising a constant/steady 40-45mph (per the speedo) following my buddy (no racing, no goofing off, just flat, straight cruising) and suddenly the steering began to whip back and forth very slightly. I noticed it and thought, "I'm sure it'll stop in a sec..." but no, it continued. I didn't break, just let off the throttle and tried to stop the wobble...but I wasn't worried about it. Then the wobble picked up gradually till it dumped me and the TW at about 35mph. Screwed up the bike and my entire body. I felt like an idiot in front of my friend, not to mention his father-in-law that lent me the bike.



Why did that happen? I've never heard of this happening before and it has me very concerned about ever getting back on a bike again when I can't pinpoint WHY it happened. I have spent many hours riding dirt bikes off road, and I consider myself a good rider. If I can't even ride down a wide, flat, straight, smooth dirt road without dumping the bike...and I can't determine how to prevent such a wreck again in the future, I'll stick to four wheels.



Is this a tendency the TW has? The tires on the bike are perfect and the bike WAS perfect. I studdied steering wobble on wikipedia and just wish I knew why it happened. I've always wanted a TW and now I don't think I do.

 

[lizrdbrth]

You never forget your first tankslapper.



As I'm sure you've discovered, there are many causes. You need to find the cause of yours.



There's something wrong with the bike.



Fork oil (absence thereof), unequal rear snail adjusters, worn swingarm bushings, loose or totaled stem bearings, tire balance, worn lowers, tubes dropped too high in the triples, loose upper triple, axle bearings, twisted frame, misaligned fork tubes, loose axle nuts, etc. etc.



For future reference, the way to handle a tankslapper (especially on a bike that's strange to you) is to push forward equally on the bars and slow down while it's still in the minor "speed wobble" category. If you wait til it enters the tankslapper category you may fall down, die nice.

 

[small's]

When in doubt gas it!

 

[evan]

something has to be wrong with that bike. Let us know what you find.

 

[admiral]

I've had this happen to me before, but not on a TW. Of course there could be something wrong with the TW, but in my case the motorcycle I was riding, XT500, was in good shape mechanically. What caused my wobble? It was the road. I hit a soft area in the gravelish/sandy road service which I couldn't see, when bam, the steering went back and forth uncontrolably. Fortunately, in my case I did not crash, but it was pretty close call. Took me over a week to be able to go to the bathroom. Took that long for my butt pucker to release!

 

[small's]

I don't think a wobble in an instance like that means there has to be something wrong with the bike. I hit a bump on interstate 70 in ohio one time on thr sv and had a nasty wobble. That's the only wobble I've ever had in 28,000 miles on that bike. Had the same thing happen when i was a kid on the rm80 while hauling but across a con field. You could have just hit something just right. My tw sometimes gets a wobble at around 60ish mph. The sr244 I put on it took moore weight to balance than what I liked. I know the wobble is from the tire so if it does it I just push forward on the bars like lizrdbrth said and it usually quits. It never hurts to investigate though.

 

[xdac]

Hey atleast with 4 wheels you dont have to put your foot down when you come to a stop

 

[lizrdbrth]

A wobble that you can ride through is an entirely different critter than a tankslapper.If you've never been there, count yourself lucky.



A flat washboard road shouldn't induce one.

 

[atleastbehandy]

I used to have speed wobble on my 2005 until I added a 2" bar riser and hand guards. Some on this forum have speculated this just masked the real issue. Basically now I am always pulling back on the bars which prevents the wobble from starting.



My suspicion is the stock front tire is to blame. Those two rows of soft knobs may not provide enough lateral support to prevent harmonic resonance.



Although the fork oil is an interesting theory too...

 

[bcscammell]

TW friends. I was riding a TW for the first time yesterday (2007 blue/white) with my best friend in southern Arizona. I have ridden motorcycles plenty during my life, and I'm not new to bikes or riding them off-road. We were riding down a FLAT, STRAIGHT, GRADED dirt road with light washboarding. I was cruising a constant/steady 40-45mph (per the speedo) following my buddy (no racing, no goofing off, just flat, straight cruising) and suddenly the steering began to whip back and forth very slightly. I noticed it and thought, "I'm sure it'll stop in a sec..." but no, it continued. I didn't break, just let off the throttle and tried to stop the wobble...but I wasn't worried about it. Then the wobble picked up gradually till it dumped me and the TW at about 35mph. Screwed up the bike and my entire body. I felt like an idiot in front of my friend, not to mention his father-in-law that lent me the bike.



Why did that happen? I've never heard of this happening before and it has me very concerned about ever getting back on a bike again when I can't pinpoint WHY it happened. I have spent many hours riding dirt bikes off road, and I consider myself a good rider. If I can't even ride down a wide, flat, straight, smooth dirt road without dumping the bike...and I can't determine how to prevent such a wreck again in the future, I'll stick to four wheels.



Is this a tendency the TW has? The tires on the bike are perfect and the bike WAS perfect. I studdied steering wobble on wikipedia and just wish I knew why it happened. I've always wanted a TW and now I don't think I do.

I don't believe anyone on this forum is going to be able to answer your concerns with any authority as no one can actually examine the bike but a good going over is certainly great advice. I do understand you not trusting the bike until you can identify what caused the problem. What I would suggest is that the tw200 is not designed to be great at anything, only good at most things. When the front end of my bike gives me feedback that something is going wrong I worry about it right away and make corrections to prevent things going from bad to worst. Being unfamiliar with the tw 200 on a gravel road of any condition at 45 MPH is in my opinion is a bit too quick. I try to stay under 65 KPH even when the roads look good. The TW does have limitations and I think if you understand them and are willing to live with them you will enjoy the bike . It's always a crap shoot when you go down on a bike and I'm glad to hear you survived.

 

[kj7687]

There isn't necessarily something wrong with the bike IMO, although there certainly COULD be something wrong with it. I've had two or three steering wobble experiences with the TW, and one REALLY REALLY bad one at 85 mph on a rough bit of road on a CBR 600 that I somehow managed to get back under control...and yea that wasn't my CBR lol ;-) The cause in your case was probably just the uneven road and your tire(s) bouncing, sliding a bit initially. It doesn't even have to be a big bump like a whoop; even a ripple in the surface can cause this. What can happen is that a little bump can cause the front wheel to skip a little to one side, then if it hits another little bump (with the tire turned slightly to one side or the other) when it "stops", it can bounce up in the air a little and go back the other way (because it is going diagonally but the momentum of the rest of the bike is tending to pull it straight forward. So then it goes back the other way in the air, and hits the ground again, this time even harder, and bounces back faster the other way again, faster and more violently each time until you crash if you don't do anything to stop it. This is basically my understanding of one cause of speed wobble, anyway. I think I understand it fairly well, having experienced it personally at least four times over the years. Although it would probably be fair to say that my attempt at explaining the phenomenon is a bit lacking. The thing to do is almost certainly (has worked for me every time) to hold on to the bars (don't FIGHT it, but hold on - you will be acting as a human steering stabilizer), and lightly apply the throttle, so as to lighten up the front end and give the gyroscopic force of the front wheel time to straighten the wheel out and sort of set it back on a straight course/allow it to "settle" back to normal. If that doesn't stop it, gradually apply the REAR brake only. If you get on the front brake in the middle of a tank slapper you'll probably just force the crash by transferring weight down onto the front wheel (which will be crooked - thereby causing a high side). All this being said, it is possible that what I attempted to describe was not actually the cause of your crash, and that there could have been some mechanical problem with the bike.

 

[lizrdbrth]

Kj, what you've just described in your own way is an under-damped front end. On simple forks like the Tw's, fork oil and fork oil level are the only means of controlling it.



Ever followed a car with worn out shocks? Lots of daylight under the tires every time it hits the slightest bump, and bouncing higher up in the wheelwells with progressively increasing violence until they're bouncing on their own like basketballs, regardless of the road surface, under their own weight and energy. The only way to stop it is to stop all momentum.



Tires and wheels belong in contact with the ground and the longer they're in the air the more mischief they can get into. Combine the above with the gyroscopic forces of a spinning tire and wheel, throw in a motorcycle's near vertical steering axis, major uncontrolled trail changes occurring every millisecond and making it even more vertical due to low or no fork oil and you have all the ingredients for just ONE cause for a tankslapper. There are many. Sometimes there are many, on the same bike.



That little wobble coming from your out of balance front tire may not be a big thing right now. It only happens at 46 mph, and you can ride right through it cuz it's gone at 48 mph, right? Ain't no thing.



Now let's say you get away with it for months. Your steering bearings are a bit loose. Maybe you noticed, maybe you didn't, or maybe you don't give a rip. Then one day you finally hit a dip at 47 mph, like you've done a zillion times before, but this time instead of that little jiggle, the steering stem starts oscillating like a dough mixer in the steering tube, the bike rips the bars completely out of your hands and if you're lucky you wake up in the hospital.



You provide the ingredients and physics will bake you a cake.

 

[sinophilia]

I experienced a bad wobble once on my (then quite new) TW125, at about 60 mph. It went away as soon as I slowed down a bit. Weird enough, it never happened to me on a TW200, and all my bikes are pretty old with very soft front forks. Well at least on a TW you don't risk crashing at 100 mph

 

[TuggerHiller]

You provide the ingredients and physics will bake you a cake.

Just remember........"it didn't happen this time" doesn't mean it never will.

Certainties like Gravity will extract thier ounce of vengence..........

 

[ronnydog]

Low tire pressure.

 

[lizrdbrth]

This is an actual tankslapper. It is also what can happen to optimists who try to ride through one. Note that it happened on a perfectly nice paved surface. If you watch the slo-mo you can see that it probably started off-camera as a small and manageable wobble, then quickly magnified as the forces mounted up. It can happen to any bike, on any surface at almost any speed.



If you've got a wobble, find the cause and fix it. They don't happen without a reason, and they never get better with time.



http://www.youtube.com/watch?v=LZ1srcQMa_0



Ronnydog is right. Lowering the tire pressure offroad will absorb a lot of this energy before it gets to this point.



It also works in reverse. One way I evaluate suspension changes is to run street pressures offroad, because if you've got an issue it will magnify it.

 

[Turwilliger]

I have experienced the tank slapper many times on my old honda cb750.

I rebuilt the forks with new seals and heavier weight oil semed to help.

The problem was due to some small pits in the fork legs.

Wvery time the oil seal passed them, it left a minute amount of oil behind.



Over time, a discrepcy between left and right oil levels would create this horrific ocillation.

So in my case at 55mph, if i hit a bump, the tank slappers would start.

First as a mild oscillacion in the front end, followed by a really violent back and forth jerking of the bars.



The thing to do: let off the throttle SLOWLY

Begin braking SLOWLY

All the while grip firmly but do not fight the bars

If you fight it, stiffen up, etc you will get thrown quickly

Let it do its thing, keep your head up and allow your arms and body to work as a steering dampener as previous poster mentioned.

That means offer resistance, but dont fight it..



Thats what i was taught and it worked.



I also found that a quick jab on the brake (cant recall if front or rear or if it maytered in my case) at the first sign of it would stop it from starting up, but i suspect it was only because i got below some theeshold speed for them on that particular bike. If i got above that threshold and hit a bump which initiated a wobble, Stabbing at the brake would quickly prove to be a horrible idea and id have to roll on the throttle which sometimes helped before braking more slowly.



It may not be the correct response depending on the source of the wobble or the bike dynamics

I only say that because speed wobbles are very very scary and dangerous.

Please find the source of it, and i woulddnt think the tw should be considered normal to have it.

Something is amiss.

 

[lizrdbrth]

Now maybe some of you can understand why I get all out of shape when Yamaha does stupid crap like eliminating the fork drain plugs to save a buck.



It discourages Joe Average from checking/changing his fork oil by making what was formerly a 20 minute job into a 2 hour ordeal. Fork oil isn't a nicety, it's a safety issue requiring regular attention.



Next they'll probably take away the zirk fittings for the swingarm bushings (another known cause of tankslappers), just as other manufacturers have done. Then you can spend hours disassembling them rather than the 5 seconds it now takes to hit them with a grease gun.

 

[Stromper]

FYI Fork tubes and seals

I have been succesful in helping scored fork tubes

Using like 800 grit . water and block dress down dings where impacts have lifted the material. Focus on the spots not the whole thing

Clean with break clean the forks a few times.

Fill divits with JB Weld

scrape (cutting motion) with sharp blade and then Back to the 800 grit to knock off excess



This with fresh seals has stopped leakage for me. I also like to buff in the moving direction fork tubes if out. Really limits stiction

 

[phazer]

When in doubt gas it!

i agree with when in doubt gas it.i think the front end of a tdub feels heavier in certain terrain. when on a washboard trail, even if the valley and peaks of the washboard are close together the front tire sometimes will slam from left to right depending on the angle you come over the peak. on my tdub i feel it more in the rear end. i always try to stay squared up with the ups and downs. i always stay on the gas because it feels like the front tire is lighter and seems to go straight easier. i find that my tdub is much easier to handle while under power rather than just putting over or around objects.