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I'm not looking for sympathy or a Dump Trophy or anything, I'm just trying to work through this and maybe see if I (or others reading the responses) can maybe learn something useful.

I'm an experienced rider, concerned with safe riding. I've had my 1997 Ducati Monster 900 for more than six years. I recently had the forks revalved at Aftershocks in Palo Alto, with the springs stiffened a bit. I was leading a group ride on Mines Road at the time. The bike was working great and I was happy with how smoothly I was able to take the turns. It was way better than the previous Mines ride when I came straight home and yanked the forks off.

We made it from Livermore to The Junction, down Del Puerto to Patterson for gas, and were less than a mile from making it back to The Junction again. I was probably going about 50 mph slightly uphill on an almost straight section of the road when I crossed a cattle guard and the bike began a violent tank slapper. The steering went lock to lock about eight times, then the bike went down on the right side and slid up the road a ways and into the ditch on the left. I didn't slide nearly as far and remained in my lane.

The tank slapper happened without warning and there was nothing I could do to regain control once it began. I've heard theories that you can let go of the bars, or give it more gas or something, but I expect that you would have to practice doing tank slappers to be able to do it when needed. Most of you have probably seen that video clip of the guy on the black bike at the Isle of Mann in the violent tank slapper who eventually goes down. Mine was just like that.

I don't remember any point between when the bike first went out of control and when I stopped sliding that I felt I had any control at all over what was happening to me.

My Olympia Kevlar leather gloves protected me well as did my Fieldsheer leather jacket and Sears work boots. The left glove is still in pretty good shape, the right one is kind of ripped on the palm and knuckle of the little finger, but my hand only has bruises at those two spots, no scrapes. I was wearing Firstgear textile riding pants over Levis jeans which didn't protect me quite as well. I have a nickel-sized scrape on my left knee where it all wore through and about four square inches at the top of my left thigh where it also wore through everything. The jacket is scraped all down the front and both vent zippers and the front zipper were damaged, but it all held up well.

I broke the bone in my left hand connected to my ring finger, plus my thumb was dislocated in two places. Boy, that was fun to get fixed. Not. I'm guessing that the violent bar action dislocated my thumb and I don't know what to blame for the broken bone.

The bike is probably totalled, since the frame is bent at the rear, the tank is really smashed, and all controls and externally visible plastic pieces are destroyed. The engine and suspension all look fine.

I know of a few other cases of Monsters going into tank slappers, the most notable case was Thomas Alberti, who founded the original Ducati Monster e-mail list. He gave up riding because of it, but he had much more serious injuries from his crash. He was a big proponent of steering dampers for Monsters after that, while I was of the opinion that they're not needed and have said so multiple times. Apparently I was wrong.

I get to spend the next few days dealing with doctors and insurance. I guess I get to spend the next six weeks with a cast on my hand. I won't be doing much more typing after posting this long note.

What good am I hoping this note can do for others?

First off, I was wondering if it is worth it to go on group rides, since I really dislike dealing with others when they crash (and I've watched three go down in front of me this summer). But I really appreciated all of the help I got from those who were riding with me. It made a big difference. I also appreciate good friends who are willing to instantly drop everything on a Saturday to drive 50 miles in a pickup truck to fetch a wrecked bike and injured rider.

Second, wear good protective gear. Leather works better than textile and textile works better than jeans. It doesn't matter how good of a rider you are, you don't know when some unexpected event will cause you to go down, so you need to be dressed appropriately all the time. Better riding gear could have prevented a couple of my scrapes, but I'm pretty sure my hand wouldn't have been much different with better gloves.

Let's all ride safely out there!
 

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Wow! Glad to hear your ok except for some minor injuries.

I can only guess as to cause somehow being related to the cattle guard upsetting the front tire's line followed by the tire regaining grip and trying to return to the direction of travel, picking up energy that may have transferred into front spring loading causing to to pass the line of travel and repeating from the other side in an ever increasing oscillation. Such an increasing oscillation requires energy from somewhere and the only two sources that come to my feeble mind would be energy from each deflection being stored in either the front springs or front tire (which acts as a spring itself) and being returned into the oscillation at just the right instant to fuel the next swing of the front end.

I had a 72 Kaw H2 (the notorious Widowmaker). It had a factory warning only to use certain tires on the front because certain other tires had proven to cause "speed wobbles" which could eventually lead to unrecoverable tank slappers. This doesn't really mean anything except in the context that sometimes a small harmonic anomaly can do strange things to the normal stability of a bike in motion.
 

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Scott, sorry about your fall, glad you are fairly okay!! Sorry about your Monster. Recovery quickly!
Could I get an explanation of a "tank slapper" please?
 

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Scott,

Wow. Sorry to hear this. Take care of yourself. You'll be back soon and it will seem like it never happened. Good luck.

Peter
 

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get well soon, Scott!

a tank slapper is when the handlebars wag back and forth from right to left in some wierd kind of oscillation. Scott's sounds more to the violent end of the scale. tank slappers can be fairly minor to abrupt and significant. the more extreme ones are so bad that the mass of the brake pads will press the calipers' pistons back into the caliper. so when you go to use the brakes, you get nothing at the lever for a couple of tugs until you press the pads against the rotor!

factors that can contribute to tank slappers:
- tire pressure
- tire brand
- tire wear
- fork angle (how high or low the forks are set in the triple clamps)
- clip-ons versus handlebars (or, where YOUR weight is located)
- obviously, road conditions
- being on the throttle seems to help induce them

chris
 
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Wow Scott. Glad to hear you are mostly OK. Nothing major anyway.

Sounds like you got some feedback into the suspension from crossing the cattle guard. The change in traction combined with an not enought weight over the front end. You were going uphill which shift weight to the rear. I am also going to assume you were on the gas, since you were heading into a straightaway, which also shifts weight to the rear.
 
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Yikes!!! Nothing you can do sometimes. Hope your better soon.

what's a cattle guard, by the way?
My desciption of a cattle gaurd: (The kind we have in the South anyway) A cattlegaurd is placed in lieu of a gate to keep cows and livestock from crossing. Typically it consist of spaced (4-6 inches between) timbers or pipes placed perpendicular to the road to allow vehicels or sure footed humans to cross. Cows won't cross, I guess because they can't coordinate all four feet (hoofs?). Most are 3-5 feet long and the width between the fence post.
 

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Hi Scott, so sorry to hear about your accident. My thoughts and good wishes are with you. As an older guy and a new rider, I've appreciated so much your postings. I've learned a great deal from them. I know your family and loved ones will rally 'round you....
 

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Dan, over on the list joked about blaming it on equipment failure. I'd actually been wondering....

I recall you had something like 16k on the forks when they scared the Hell out of you on the last Mines ride. I just had mine RacTeched after 12k miles and have to say they didn't NEED service.

The fact that your fork degradation seemed rather sudden (at leat that's what I got from your postings) and that the bike did something very strange after the service, makes me wonder if something else were involved.

How about a cracked weld up around the steering tube? Enough to make the bike squirelly before. Then the cattle guard could have broken it even further leading to the oscillation.

Just a wild @ss guess. If your head tube has cracked welds now, it may not prove much since you hust had a shunt. But it'd be interesting to see.

In any case. Heal up quick and hope the rebuild/replacement goes well.
 
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Wow That sucks !!!!!!!(I'M A Neewbie Rider)
But I am really happy to hear that your ok Scott,and I hope You recover Quickly and want to ride again.....
 

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Jeez, Scott, your message scared me a little, I've crossed 50 or 60 cattle guards in my regular rides (they are all over the place here). I hope you heal up quick and hopefully have the desire to continue riding (I think I'd be a little skittish). Thanks for your info, I'll be more careful about cattle guards, and I'll invest in a "real" riding jacket now. Get well soon.
 

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Hey Scott-
I know that this was not your first time out on this road. I know it's a favorite of yours. So I've been wondering what could have been different this time...
I know that on the way out to Hwy 5 I was having fun riding behind you. We were carrying a good clip, although you said it was 'comfortable'. On the way back Paul was following you and I hung back to do the run more on my own, to learn the road. I was surprised to see you down on a straight...were you going faster than you usually do?
Paul heard a loud 'thud' when you hit the guard...did your forks bottom, distort or flex?
You were commenting on the nice ride from your forks...did the nicer ride inspire confidence that had not been tested yet as to new limits? Questions, questions...I know you're a great rider. I look forward to riding and learning more from you.
Good to hear you're healing.
Cesar.
 

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Scott,

Having been in a similar position to you several years ago, I can only sympathise.

Get well soon, and be sure to follow ALL the Physio advice when the cast comes off, I didn't :-[ and now have only 85% use of my thumb which I damaged.

Ride safe guys & girls.

Dave
 
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Glad to hear you are (mostly) ok.

That is a pretty scary story. I'm a safety-conscious rider, too (no speed demon tricks for me!), and your story is scary because it sounds like it could have happened to even the most conservative rider.

Take care and get well!
 

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Somewhat OT, but I noticed no damage to the main frame section and engine at all--this on a bike without frame sliders. Granted, they could've possibly prevented the rearset and pipe breakage, but that seems like a side benefit. How necessary are they on the Monster?
 

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Wow Scott, I'm glad you made it through with minimal damage to yourself. I was just in a suspension setup clinic and was warned that if the rake is to steep (not enough pre-loading) then you have a higher probability of the steering going into head wobble (tank slapper is the extreme case of head wobble) Geezer thought that he heard a rider hear a thud that might have been bottoming out of the suspension. That would indicate not enough preload and a steep rake. I'm not sure if you had an adjustable front suspension or not. Though, I would think, with a stiffer spring should translate into more preload (less fork displacement from stiffer spring). I guess the only other thing that could have upset the rake is putting a lot of wieght over the handle bars and removing wieght from the rear shock. That would use more of the fork displacement before bumps while reducing swing arm displacement.

Wow, I'm definitley going to check my preload before my next ride!

Get well soon Scott!

Borg Girl
 

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GOOD LUCK WITH THE HEALING SCOTT!! ;D
Does anyone have any suggestions for preventing
"tank slappers?" Any regular maintanace that can be done to reduce chances of this happening.
 
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