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General Category => General Discussion => Topic started by: Rough Edge racing on January 18, 2016, 05:48:03 AM
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Have any of you had a front end wobble or what's known as a tank slapper? What type bike and what was the bike and rider doing when the problem came on.
A group of bikers was discussing this and it seemed to happen to just about any bike if the conditions were just right... and sometimes there seemed to be no reason for it. There was no agreement as to the causes...
I never experienced a true tank slapper but have a few swiggle their heads after unloading the suspension while cresting hill at high speed...
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I have never owned a bike that did it, but I have ridden a few.
One in particular was a Suzuki 500 twin, the 2 stroke. Taking hands off the bars caused a massive wobble. Oddly my brother's 500 didn't do this.
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I never had a full tank slapper, but I did have a high speed wobble ( the precursor of a tank slapper ) on my BMW. I made a pass around a semi on an interstate at around 80 to 85 mph with the bike loaded with camping gear. There was also about a 30 mph quartering tailwind. As I broke through the truck air blast and was moving into the lane ahead of the truck she went into a wobble ( the BMW rubber cow ) and head shake. Scared the sh*t out of me. It eventually stabilized ( or I wouln't be here to talk about it now )
When I arrived at the BMW rally I was headed to, we talked about it and the first thing people said was "ah your steering head bearings are to loose" - nope. Never did figure out the cause. I did, however, put new tires on the bike a week before this incident and the replacement tires have a more round profile on the front and, to be honest, I was running pressure higher than normal
When I got home I spent a lot of time researching the subject and I found that yes, under the right conditions, and two wheeled vehicle ( bicycles included ) can go into a wobble and possibly an unstable wobble that would be called a slapper and down you go. Look for tank splappers on You Tube. There's a few clips on this subject. There's also one about Harley baggers going into the death wobble at speeds around 40mph.
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Here ya go: https://youtu.be/z3OQTU-kE2s
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When I was a young adult I became aware of the importance of proper tire pressure. Tank slapping happened to me while riding a CR250. On acceleration at approximately 50MPH on an irregular dirt surface the handlebars suddenly oscillated from one side to another. This back and forth movement increased so fast that it caused me to really clamp on the grips. There was no stopping it by physically overpowering it. My grip on the throttle cause a sort of whiskey throttle that increased my speed and tank slapping motion. All this time I continued to go straight. I was able to recognize that my increase in speed was making it worse and focused on trying to release the throttle without losing my grip. I was able to slow down. I actually don't know if I was truly able to release the throttle to end the condition, the bumps on the ground changed, or drag from my rear brake finally got grip. This all happened for a few seconds at about 50-60MPH.
After I calmed down,I realized it was caused by too much air in the front tire because the front end seemed to bounce instead of absorb the bumps prior and during the event. I severely overfilled it and will never fill a tire by feel again. I learned the hard way.
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In the late 70s on my Suzuki GS400. I had not owned the bike long and had a local dealer put on a new front tire for me while getting some other service done. Later I passed a car between 60-70mph. When I leaned a bit to enter back into my lane the bike went into a full blown tank slapper. Somehow kept it upright and was able to stop successfully. Started checking things and found all four fork pinch bolts loose! Never since then thank God. It does get ones attention.
GliderJohn
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The first time I saw the results of a real tank slapper ( not a high speed wobble ) was in the late 60s at Santa Fe Speedway outside of Chicago. Guy on a sportster was coming out of a turn in front of the stands and went into a real slapper-the kind you can't control. He went one way and the sportster went airborne.
Bike wrecked and he had a broken leg and arm
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I have had many occasions of beginning slappers that I got under control. The worst one was on a 650 Triumph during a TT race long ago. It was a full on slapper that took me right out of the competition although i did not crash.
Having owned and ridden sidecar rigs since 68, I can say that the tendency is much greater with them than with solo bikes.
With solo bikes, the most common cause is a bit of slack in the steering head bearing and tightening it up just a bit usually fixes it. There are many other things that can be a cause but that is by far the most common.
On my Triumph in the race, it was a loose rear axle nut.
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Another common cause is a squared off rear tire
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Quote from RayB:
Another common cause is a squared off rear tire
Ah crap! I live in Kansas! Almost always end up with a squared rear tire before it is really wore out. Never had nary a wobble, guess knock on wood.
GliderJohn
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I have never owned a bike that did it, but I have ridden a few.
One in particular was a Suzuki 500 twin, the 2 stroke. Taking hands off the bars caused a massive wobble. Oddly my brother's 500 didn't do this.
Funny that you mention the T500...mine would do the handlebar-hula on occasion, also. Heavier fork oil and a set of S&W shocks improved that bike a great deal...
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Yep, had one while accelerating hard on my Yamaha XS1100 right after changing tires. Hit a small deviation in the road surface doing about 90MPH and wham, just like that the bars were slamming from stop to stop. Lasted about a second or two and it ended. Felt like minutes. I thought hitting the pavement was inevitable, but not. I honestly believe that while accelerating hard I may have been holding the bars too tight and that may have contributed. I went back to the spot and could see the rubber skid marks left in the road from the front tire. After that I never held a death grip on the bars and never owned a bike without a steering damper installed.
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On my CB550 Honda right after I picked it up from having something done to the front wheel( i can't remember ) at about 65 full on tank slapper, rolled off the gas and got it back, Started doing most of my own work after that.
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My conclusion on the tank slapper bit is that there are too many variables to boil this subject down to a few. Suspension, rider error, tires, road conditions, chassis design all enter into it. Our ignorance on the subject makes one re-think the risks we face riding motorcycles.
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I had a low mileage Goldwing almost throw me off at about 90, I put it down to the screen vortex shedding.
The Goldwings had a heavy weight fitted to the steering column behind the headlight, I think it was to avoid tank slap
Ray B,
Yes I did a few times but I was always nervous about it.
The bike was practically new when I sold it, about 4K miles
I found a picture of the weight, lets see if I can't post it.
(http://i1304.photobucket.com/albums/s526/Kiwi_Roy/Misc%20Pics/Steering%20Weight_zpsazyicwxd.jpg)
Note the warning notice which says
WARNING
Do not remove this weight when riding with faring to prevent an accident
Without this weigh steering inertia moment will be reduced resulting in
loss of control and motorcycle stability
IMHO the California II of the same year is light years ahead of the Honda in the handling department.
The Honda on a bumpy sweeper was like riding a garden gate against the Guzzi riding on rails.
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Kiwi Roy
Did you ever take it back up to 90 after that? If so, did it wobble again?
I wonder if fairings don't provide a little lift on the front end and unload the front tire some at certain speeds. Honda's weight on teh steering stem could have been a preventive measure against lift.
I have a WindJammer on my R100 and was thinking about lift...I don't have any aerodynamic data and I doubt if Mr. Vetter ever ran wind tunnel tests.
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Worst one was on a Hodaka Combat Wombat
Full throttle on an abandoned rail line
Lock to lock with the back wheel stepping out 4 feet +/- to each side
It was massive fun
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I've had it happen a few times rolling downhill with no throttle with my hands off the bars. It'll wake you up pretty quick. Take you to oh......pucker factor 6 of 7.
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I've had a tank slapper or 2 but don't try to diagnose why. When it happens my dirt track riding experience comes into play to live to ride another day. I think it's when for a moment your whole bike gets light and somewhat airborne for whatever reason. Or if you ride over something slippery upright you can go into a TS. If TS happens to me repeatedly then I will look for reasons why.
Headshake is a different phenomenon and can happen to any MC front end at a certain speed for your bike/weight distribution when coasting. When operating a sidecar rig you're dealing with headshake a lot because your rig is not balanced.
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Never had anything remotely like that happen, not even a wobble.
I understand the phenomena is replicated on the front wheels of a shopping cart, you know when you push the cart and the wheels wobble rapidly side to side. There is "zero" steering angle on those wheels, so it makes sense it would be worse with bikes with sportier front steering angles
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"My conclusion on the tank slapper bit is that there are too many variables to boil this subject down to a few. Suspension, rider error, tires, road conditions, chassis design all enter into it. Our ignorance on the subject makes one re-think the risks we face riding motorcycles."
Well said, Sir.
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My conclusion on the tank slapper bit is that there are too many variables to boil this subject down to a few. Suspension, rider error, tires, road conditions, chassis design all enter into it. Our ignorance on the subject makes one re-think the risks we face riding motorcycles.
Best explanation yet.
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My conclusion on the tank slapper bit is that there are too many variables to boil this subject down to a few. Suspension, rider error, tires, road conditions, chassis design all enter into it. Our ignorance on the subject makes one re-think the risks we face riding motorcycles.
+1
Had that wonderful phenomenon occur on the MV. Before attempting to mask the problem with a damper, I went for a basic setup. Stock settings were more appropriate for a 5' jockey rather than a 6' 185# mouth-breather like me. Made an impressive difference.
http://www.europeancycleservices.com/
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Kiwi Roy
Did you ever take it back up to 90 after that? If so, did it wobble again?
I wonder if fairings don't provide a little lift on the front end and unload the front tire some at certain speeds. Honda's weight on teh steering stem could have been a preventive measure against lift.
I have a WindJammer on my R100 and was thinking about lift...I don't have any aerodynamic data and I doubt if Mr. Vetter ever ran wind tunnel tests.
Vetter included instructions to mount their fairings so that at a certain speed, there was actually a down force rather than up lift, at least for the Quicksilver fairings. He even referenced the amount the fairing should load the suspension so you could measure it.
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Once on a Yamaha 1700 cruiser. Just coming out of a slight downhill bend. No warning it just happened. I never discovered the cause, (but suspect the front end slipped a little) I rode the bike for 120,000km's and it only ever happened once. I would rather not experience it again.
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The only time on a Guzzi was on an 85 LM 1000 w/16" wheel, stood on all brakes and it subsided once I got back down to 90mph. Thought I was going to hop off for a few seconds
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I have never experienced one, but I always understood that you were supposed to hit the throttle to settle a tank slapping event.
Reading this thread it seems that most hit the brakes and came out of it. Maybe coincidence?
Hmm.
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Most real tank slappers , as opposed to weave , happen so fast the rider is only along for the ride .
Dusty
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I heard horror stories about the dreaded 16" wheels on mine. I can induce a 'wobble' if I load it up on the rear so the front end unloads. It is kinda mild and only happens if I take both hands off the bars. With the bike loaded 'normally' it doesn't happen at any speed (tested up to 115 :) ).
I did have one of those 'moments'. Fast sweeper with tire ruts. I took it a bit fast so I drifted to the outside. As the front wheel 'hopped' over into the outside tire rut (unloading the front tire almost completely) it started a really bad wobble. I had just started to wonder how bad it was going to hurt, going off into rocks at 80mph, when it calmed down and just carried on through the rest of the corner. I did nothing to correct it. I froze in position. I just let the bars do their thing. I think I let go of the throttle, I did not apply brakes (have heard conflicting stories about that method of correction). My assessment was that as soon as the front end loaded up again, it went back to a stable condition.
PS if you watch race bikes, when they crest a hill and the front end comes down just a little off, they get a good slapper going.
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https://www.youtube.com/watch?v=LW0UAgzntao
this would be better if he fell on his ass.
#93
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Charlie B is on to it here . What most describe as a weave is due to chassis and swingarm flex inducing a slight back and forth movement . A true tank slapper is caused by front tire deflection . The giant gyro up front is trying to self correct , in the process it over centers several times , finally coming back to center , hopefully :laugh:
Dusty
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Had one on a naked 82 goldwing, going slightly uphill on a left hand sweeper. Just coasting off throttle going about 65. Started the violent head shake and I won't say I knew what I was doing but stomped on the rear brake and recouvered. It only ever did it on the 1 particular freeway exit and never did it again. :boozing:
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Never had it happen yet that I can remember but I am wondering if it has to do with flex in the chassis allowing the front to adopt a different line than the back. The front would then try and correct, but at speed would become a series of over shot corrections. The similar analogy would be while ice skating with both blades in line . I can remember while learning this as a youngster if the front blade got even slightly misaligned a horrendous wobble could result. I am not certain that a steering damper would even help in this situation as once out of line, the front will violently try and correct. Depending on speed the pulses back in forth would change in wave length but I would think it would be uncontrollable and would only end when re alignment is achieved or bike and rider are on the ground. I have always thought that the most important safety feature on a m.c. is chassis rigidity.
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I was tuning a customers 85 LM doing the wide open circuit when it hit 125 it started a shake, when it hit the stops the second time is when I tried the brakes. Accelerating wasn't working, letting off the gas loaded the front and it got worse.
I didn't really want to trash a new bike. First LM to have Koni shocks. They were so fast compared to a LM3.
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when :May 26 th 2013 , around 4 pm
bike : 1980 moto guzzi sp 1000 le mans clone
location : crappy NY highway .
I had a tank splapping at 90 mph..... i am glad i am here to tell the story...( and glad the cars behind me had good brakes )
Right after i put a set of new fac dumpers i took off to try the bike.... the front end felt good but way too stiff .
I ran over some crappy/uneven asfalt , front end started slapping ....went down on my left side , hit the ground with the helmet 3 times ( thank you Aray ) and left shoulder.... i turned on my back while sliding on the ground ( thank god i had a back pack with a pair of brand new sneakers inside ) .....
I never wear boots /gloves and leather jacket but that day they saved my fingers /feet and left arm .
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Not a tank slapper, but a high speed wobble on an Eldorado. Wrong front tire.
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https://www.youtube.com/watch?v=LW0UAgzntao
this would be better if he fell on his ass.
#93
There wasn't one single tank slapper in that whole video.
Ciao
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I always understood the long legged tontis were less inclined to tank slap - even though they came with steering dampers? so a shorter chassis and steep rake more likely..
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If any of you who have experienced a handlebar wobble think that is a tank slapper ..... well, sorry to tell you, a tank slapper is just that ..... the bars bang harshly against the steering stops, and the bike is totally uncontrollable. And believe me, you don't have enough arm strength to hold the bars steady. It is a mechanical animal totally out of control .... the laws of physics have taken over!
2x for me. First was nearly 50 years ago, on my BSA Spitfire Scrambler. Second time, and a huge surprise, on my BMW R100GS, and not at more than 30mph.
An amazing thing ....!
Bob
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Mine happened on a 96 gsxr 750. Crested the top of a hill and had five cars in front of me. The lead car decided to make a left turn but stopped in the turn causing everybody to brake hard. My slapper started immediately and started to shake violently. No room to do anything with the throttle so i let off the front brake and started alternating back and front brake, got me out of the slapper. Talk about butt pucker! Why did it happen? My take on it is a lot of stored energy while braking and a short wheelbase. Stay loose my friends, I think that was the only thing that saved the day.
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If any of you who have experienced a handlebar wobbler think that is a tank slapper ..... well, sorry to tell you, a tank slapper is just that ..... the bars bang harshly against the steering stops, and the bike is totally uncontrollable. And believe me, you don't have enough arm strength to hold the bars steady. It is a mechanical animal totally out of control .... the laws of physics have taken over!
2x for me. First was nearly 50 years ago, on my BSA Spitfire Scrambler. Second time, and a huge surprise, on my BMW R100GS, and not at more than 30mph.
An amazing thing ....!
Bob
You are correct Bob. With a full blown tank slapper you are a passenger, hang on and pray as the steering goes stop to stop.
A weave which can lead to a tank slapper is something you can ride out of if you know how, generally by getting hard on the gas.
I experienced a slapper coming onto the straight at Phillip Island on my GSXR1000 about 3 years ago. Hard on the gas onto the straight and pick the front wheel up an inch or so as usual but this time it came down slightly crossed up. Forget about any ability to apply technique,way too violent for that. On about the 3rd hit of the steering stops it straightened up but I was just hanging on for dear life thinking I'm going to be off this thing in a straight line in front of the pits, how bad will that look.
Then I got to turn 1 without any front brakes due to brake pad knock off due to the violence of the slapper. Fortunately i was half prepared for that and some furious pumping of the lever got them back.
Next visit to the track I had replaced the std damper with an Ohlins unit adjusted so tight I couldnt ride it around the pits,ha.
Got over it though after a couple of sessions.
Ciao
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I have never owned a bike that did it, but I have ridden a few.
One in particular was a Suzuki 500 twin, the 2 stroke. Taking hands off the bars caused a massive wobble. Oddly my brother's 500 didn't do this.
Interesting. My experience too. Suzuki Titan 500 2 stroke street bike, crossing over some railroad tracks at a sedate speed. Went from lock-to-lock, all I could do was let it run its course. Made a big impression on me, since I owned that bike back in the mid-70's and STILL remember it.
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In 66 I was northbound on a two lane in Illinois. Coming towards me at about 70 or more was a BMW with earles forks.
I saw him wobble then go into a full house tank slapper then down on his left side just before he slid past me. With my wife on the pillion, I still was able to get slowed and U turn in time to se his bike slide to a stop. He was lying unconcious
in the middle of his lane and the bike was three telephone poles further and on the shoulder. Leaving my wife with him I raced to a farm house and called police. After the ambulance took him away, the leo and myself examined the bike.
I pointed out the steering damper, a hydraulic shock absorber type, had snapped off from one of its mountings. I would bet that it snapped under strain and that allowed the tank slapper. It was the most violent tank slapper I can remember seeing.
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I'm with DRLAPO - worst and really only full on "tank slapper" for me was on my Hodaka; either my Super Rat or Wombat, I don't quite recall which... Both? In any case, it wasn't a Combat Wombat. I figure my mere Wombat was the conscientious objector of the line.
Anyhow - I do recall the incident in that I was blasting along the railroad tracks outside of Anoka, Minnesota. Being completely beyond rational or analytical thought as it was the first time I was able to get it into top gear, I was little more than a pubescent meteor temporarily skimming the earth unwittingly waiting for inertia to tire with me and let gravity have its way.
My first sign that something might be amiss was the front getting a bit upset and by some cinders. Knowing little of the dynamics of what was going on - which is to say I had the vaguest notion as to why a motorcycle didn't' topple over - I paid no attention to how little contact the front tire really had with terra-oucha.
Of course, in 100-mile-an-hour-with-yer-hair-on-fire fashion, I had too much weight over the rear in my best "Then Came Bronson" riding style.
The cinders set the front a-twitter and the rest was me just waiting to see how it all played out.
I had a healthy though still insufficient respect for the tracks there in general and the cinders and ties in particular as we'd clashed in the past while snowmobiling along them. Great vast amounts of winter snow and ice might go a long way with adrenaline in temporarily muting the pain but I was still very conscious of the memory when I became an engaged bystander on my Hodaka.
I had maybe, what 3/4 - 1 1/2 seconds of alarm at the bars developing a mind of their own and then it was lock to lock, no half measures, hell in a hand basket horror as it shook holy hell outa me till my arms were thrown well off the bars.
By then I'd also been bitch slapped by all three of Sir Isaac's laws resulting in lost footing and repeated nard abuse.
Oddly, as is often the case in general and (not going unnoticed by me all these years) me in particular, nature took pity on a fool. In removing me from any significant input while having blessed me with an outstanding sense of balance, the world came back a-right as the bike slowed and I stayed on the chrome side.
Slow, stop, commence to shake and then I went back to see what I had hit - being completely ignorant of the concept of a "tank slapper" I assumed I'd been undone by some hobo-thrown trash. Walking along the cinders, one thought kept coming back to re-ignite the shivers and that was that I wouldn't be going home with bedding material in my skin without the benefit of early onset frostbite to see me through the trip as it had in winter.
Initially I had trouble reading the tracks but eventually I light upon some standard if light and dusty tracks. When I turn to follow them to the bike they all but disappear as anything approximating a motorcycle track and become this weird display of wildly though geometrically placed scuffs of impossible width in their presentation. The notion that the Hodaka was moving that insanely beneath me only made my tensions worse.
As I walked you could see just where it ceased to grow worse and immediately began to stabilize - this is probably where the cosmos jerked the last of my input from the scenario.
Man, but I'll tell ya, I sat for quite some time on the banking before starting that thing up again and then I never used up even third gear on the way back to the shop.
Since that swirling vortex of doom ride - I've figured everything else to be excessive weave.
And these include ill advised mods on top of poor maintenance of Kawasaki triples; 500 & 750 and failure to properly reassemble the front end of my '82 Katana including not replacing the factory front fork brace and then "test riding" it on suspect tires. Yup, that was a test alright!
Anyhow - Tank slappers? Yup and no thanks!
Todd.
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An old but informative British study on wheel wobble. I am surprised that how to handle this is not taught in basic training. I have had it happen only on bicycles and leaning down and forward has stopped the problem.
http://www.youtube.com/watch?v=z3OQTU-kE2s&sns=em.
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very good video. I remember that some of those 70s bikes were a handful.
Funny, they didn't run a Guzzi in their film.
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My 1983 Suzuki GS750e (16" front) had a very predictable high speed wobble (those Brits in the video call it weave) north of a hundred mph. Once you knew it was there it was no problem; you just needed to add more right hand. If you stayed at the speed too long it would start getting interesting.
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I've probably suffered more tankslappers on more different motorcycles than anyone else here. I hope so, anyway...
The two most common, as well as least known, causes are;
1. Loose steering head bearings.
2. Rider pulling backwards on handlebars instead of pushing.
#2 is by far the more common, and the worst; because this is usually caused by high speed and the rider in the wind.
If you get a scary weave at speed, lean forward and put weight on both bars. You'll find it goes away.
#1 is a death warrant if you find it the hard way, as I did twice on a racing H-D sportster. Setting bearing preload isn't hard, it's just tedious. But it's critical.
A few bikes seem to have a natural problem here; H-D FLT fixed-fairing dressers, which is usually fixed by keeping the air in the forks up to spec; and any Kawasaki 2-stroke triple. I was thrown from my '75 500 twice with no warning and collarboned myself once.
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I was looking at a Suzuki 750 water buffalo as my potential next ride many years ago and took it for a test ride. At about 70 mph the front end went into wild gyrations and scared the crap out out of me. I slowed down and got it under control. I rode slowly back to the owners home said - no thanks.
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A "violent weave" following a rear tyre blow-out at 100kph. With a truck behind, I chose to lay the bike over on the side of the road. New tyre and new tube 200km previously. I don't know if laying on the tankbag would have helped or not. Perhaps. "Forensic "analysis suggested a faulty weld of the valve stem to the extra thick tube. Lots of bent bits straightened, a bit of paint, ruined luggage replaced & another new tube, was back on the road in a couple of days, by which time the sore shoulder was fine. The armoured leather worked just peachy.
Mal
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I've had two on the Monza. First passing a car at around 80 indicated (lol, 70 or so) with a strong crosswind. Front started to weave, building amplitude. I gently rolled off the throttle and pulled off the freeway at the first reasonable spot. Tire pressures were way too high. Plus crosswind, plus handlebar-mounted fairing that looks like it might have more lift than downforce.
Second time, also around 80 indicated, in deep nasty rain grooves with worn tires. Reasonable tread but cupping on the front and a bit squared off on the rear. That particular section of freeway is noticeably nasty even in a car.
Never a problem on the Le Mans with the 16" front wheel. Never a problem on the V50, so possibly the Monza fairing is suspect in some conditions. V50 has a Givi screen and 7" replacement headlight, so there's a bit of Lotus 25/33 venturi effect and possibly downforce at work.
Rain grooves are another problem…
cr
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You are correct Bob. With a full blown tank slapper you are a passenger, hang on and pray as the steering goes stop to stop.
A weave which can lead to a tank slapper is something you can ride out of if you know how, generally by getting hard on the gas.
I experienced a slapper coming onto the straight at Phillip Island on my GSXR1000 about 3 years ago. Hard on the gas onto the straight and pick the front wheel up an inch or so as usual but this time it came down slightly crossed up. Forget about any ability to apply technique,way too violent for that. On about the 3rd hit of the steering stops it straightened up but I was just hanging on for dear life thinking I'm going to be off this thing in a straight line in front of the pits, how bad will that look.
Then I got to turn 1 without any front brakes due to brake pad knock off due to the violence of the slapper. Fortunately i was half prepared for that and some furious pumping of the lever got them back.
Next visit to the track I had replaced the std damper with an Ohlins unit adjusted so tight I couldnt ride it around the pits,ha.
Got over it though after a couple of sessions.
Ciao
I can hardly imagine at racing speed! It was so unusual ..... my Beemer went into a tank slapper at no more than 30mph in a turn after both front and rear tires slipped to the outside of the turn in unexpected gravel. Damned bike 'walked' across the center line toward an electrified barbed wire fence with the steering banging off the fork stops. So lucky that (a) no one was coming the other way, and (b) that the tank slapper quit on its own before I experienced the feeling of riding thru an electrified barbed wire fence!
I could not believe the violence of the tank slapper at only 30 mph or so.
Bob
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Borrowed my bro's '53 AJS 500 to go sit an exam when I was still at school. The bike was well and truly "pre loved". :shocked: Straightened up from going around a tightish corner at about 25mph when all hell broke loose. Handlebars whacking from side to side finishing with me being thrown up and off. As I lay there bleeding on the road an older guy wandered up and asked if I was all right. Well, I wasn't but I said I was. He looked at me and said, "in all my life I have never seen a bike do that"
Funnily enough, a few months later a bus did not give way to him and Tee boned him so hard it drove the corner of the battery case a couple of inches in to his leg.
50 years on and he still has the bike waiting to be repaired. Says it is the next cab off the rank after the Vincent....and after the De Soto and........... :popcorn: :popcorn:
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There's a lot of experience posted here. What do we conclude about causes, predictability of the hazard, and prevention?
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Never had one. There's some basic physics going on that I don't understand but it seems like an unloaded front end from some cause is necessary for true TS. I can't imagine a TS on the Sport 1100 remembering what riding it felt like - my weight was all over the front end considering that riding position. It would seem like an upright riding position or a cruiser position is more likely to contribute than a sport position. TS prevention might be a neat thing for some engineer working on traction control systems to take on. Maybe a front tire sensor that indicates impending loss of traction - probably the whole event happens so fast that any warning would be too late though.
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My conclusion on the tank slapper bit is that there are too many variables to boil this subject down to a few. Suspension, rider error, tires, road conditions, chassis design all enter into it. Our ignorance on the subject makes one re-think the risks we face riding motorcycles.
Yes well put....and add to this rider choices...I can't think of a good reason to take both hands off the bars...only bad results can happen.
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1986 on a Honda CB1100F. At about 85 I came around a corner and up ahead was a State Patrol with radar. I hit the brakes hard and went into a full blown lock to lock tank slapper. Have no idea what I did at that point. I think I stayed on the brakes. It ended up tossing me off the bike and earning me my first and only trip to the hospital due to a crash.
Never did figure out what caused it, so I blamed it on the bike rather than me and moved on to a Kawasaki Ninja 750.