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Harley wobbling at 85-90 mph on I-24 east

Ozymandias said:
I was trying to stay out of this but since this thread is STILL going I'm going to toss this out there and hopefully get this lame ass beat to death conversation about steering dampers out of this thread. :deadhorse :twofinger

IIRC, HD front and rear wheels, until recently, were not perfectly in line with each other. The rear wheel was set just slightly right to accommodate the wide belt drive and with a narrower tire than should have been on a bike of that size and weight. This could cause a wobble during a turn to the right at higher speeds and traction is being pushed caused by the rear wheel trying to get to the outside of the front wheel's track.

The solution... put the wheels in line with each other and a wider rear tire.

Using a damper to solve a geometry problem is stupid. I'm not trying to bait, but c'mon. Let it go already! :x

Edit: Dampers have their place, but it's not a fix for everything. My FZ-1 and BMWs don't have one and I've never seen the need. My F4 had one so do my race bikes...
Click to expand...

If its true, the front to back wheel offset, that's something about any motorcycle that I didn't know!

Agree that putting a damper on is something that, in my opinion. should never be done in order to mask a defect, a weakness in the structure, or an outright design flaw.

In my mind, a damper is something you put on IN ADDITION to a perfectly straight, rigid, and undamaged frame, that just so happens to have its steering rake angle on the smallish side ON PURPOSE in order to facilitate more rapid direction changes in exchange for giving up some straight line stability and increasing the probability of a tank slapper.

Less than a bandaid, steering dampers should be seen more as a part of the design compromise process because you are using it in order to be gaining something in handling, not because your bike handles badly in general and its a cheap way of avoiding fixing a systemic problem of design, correctly :)
 
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My mistake. It's offset to the left.

http://www.hdforums.com/forum/softail-models/462931-rear-wheel-offset-normal.html
http://www.hdtalking.com/softail_models/44507-offset_of_rear_wheel_tire.html

I don't really recall the details to be honest. Fix geometry and shitty suspension issues. I get it if you can't fix the fundamental design you have to do something, but considering the wobble is coming from the rear that would be massively hard on any damper to actually solve that wobble and is essentially the same thing as trying to use a scalpel as a sword.

<sarcasm>
Gee, when I'm driving down the road in my car it bounces all over the place. To fix it I put those coil spring clamps in so the springs don't have so much travel. So what if the shocks have 150,000 miles on them?! :facepalm
</sarcasm>
I've witnessed this several times myself and just the other day on my way home even. Some HD bagger blew past me on 680 and started wobbling going up the hill just outside of Concord then powered down cutting across all 4 lanes. He almost got plowed at one point when he didn't look and cut off a big truck too but at that point I think he was in a panic state.
 
First I will appoligize right up front for going off of the reservation with this topic with information from my crash reconstruction buddy. The following is from the email he sent me.

Because the motorcycle is a single track vehicle with a pivot point between the front and rear tires it can experience a resonant vibration/harmonic at either the front or rear portion of the motorcycle. The front harmonic a lot of times is called wobble and it oscillates at about 10 Hz (10 times per second). because this is a harmonic oscillation it builds on itself and get much worse with time, in this case a very, very short time. The front general builts so fast that a rider goes down before he can do anything about it. A lot of front wheel wobble is due to short trail.... so some modifications can actually put the motorcycle into the wobble configuration.

The rear tire oscillation is generally called weave and it occurs at about 3-5 Hz. This is the much less severe harmonic on the motorcycle in that you can "save" the motorcycle fairly easily. You can feel it building up and it is generally speed dependant....that is it occurs in an acceleration and/or some type of turn.

Why do I know about this, because my old KZ1000 Police Motorcycle (Yes I am an old guy too) would go into a weave anytime I was over 90 mph and going into a sweeper.... the cause... the radio box on the back was mounted with dampeners that allowed it to sway, once I got up to speed and turned, the movement of the radio box would set off the back end. You can feel the weave building and all I had to do to set the motorcycle right again was litterally lean forward and down onto the tank to change the weight distribution on the motorcycle.... along with a slight roll off of the throttle.

Braking is absolutely the worst thing that you can do because the static friction force of the tire is actually keeping the motorcycle from going down. Take this away and the weave builds and the motorcycle low sides.

And in addition to experience where did I get the above information, the 2nd and 5th additions of a book titled "Motorcycle Accident Reconstruction and Litigation" you can find the book at Lawyers and Judges publishing.


I am just passing along the information from riders involved in another side of motorcycle riding.
 
Feanor said:
If its true, the front to back wheel offset, that's something about any motorcycle that I didn't know!

Agree that putting a damper on is something that, in my opinion. should never be done in order to mask a defect, a weakness in the structure, or an outright design flaw.

In my mind, a damper is something you put on IN ADDITION to a perfectly straight, rigid, and undamaged frame, that just so happens to have its steering rake angle on the smallish side ON PURPOSE in order to facilitate more rapid direction changes in exchange for giving up some straight line stability and increasing the probability of a tank slapper.

Less than a bandaid, steering dampers should be seen more as a part of the design compromise process because you are using it in order to be gaining something in handling, not because your bike handles badly in general and its a cheap way of avoiding fixing a systemic problem of design, correctly :)
Click to expand...

:thumbup Exactly :thumbup

First the rider has to be a savvy rider...Know there is no problem, because they aren't such a miserable chowder head,
to turn a blind eye to problems.
Then they have to know how to finish up their bike, for the use it will be given.

The factory doesn't know you, they don't know the use it will see. They didn't build the bike for you...They built it for a market.

There is no Band-Aid fixes, or cover-ups. Only miss-guided chowder heads.
 
…Says the guy with the bike built with a HINGE in the middle of it!
 
Holeshot said:
…Says the guy with the bike built with a HINGE in the middle of it!
Click to expand...
Don't you just hate that? The most annoying part of bi-cycles. :x

I am getting bored with this crappy chassis/suspension wobble talk, so I am upping the ante to TRUE tank slappers: Can your HD do this?

[youtube]LZ1srcQMa_0[/youtube]

If not, then stop whining like girlie-men and ride the stupid p.o.s. :twofinger
 
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louemc said:
Hinge My ass :laughing You aren't riding my bike...
You must have acquired that impression somewhere, I don't know how or where...But Your wrong.
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"your" 05 ZX10R was notorious for the back chasing the front on entries…no one could make them work to go fast, but they sure as shit made you feel like you were going fast. I loved my 04, but the times never materialized on it for me, same as all the other fast guys on them.

Still, one of the funnest bikes I've owned and I loved it. But it was, sad to say, slow by the stopwatch.
 
Holeshot said:
"your" 05 ZX10R was notorious for the back chasing the front on entries…no one could make them work to go fast, but they sure as shit made you feel like you were going fast. I loved my 04, but the times never materialized on it for me, same as all the other fast guys on them.

Still, one of the funnest bikes I've owned and I loved it. But it was, sad to say, slow by the stopwatch.
Click to expand...

Well it did make the MCN testers cry like little school girls..It's a Beast :rofl

So I had to get it..and then tweek it. and...for me, there is, and never will be, anything that suits me in my use, better.

I have the luxury of suiting myself...What others do, :ride in different places, means nothing to me. :thumbup
 
Holeshot said:
…Says the guy with the bike built with a HINGE in the middle of it!
Click to expand...

There is no hinge in the middle..What You're referring to, is the power, that can be insanely quick,
when combined to the amount, and...when the rider hasn't enough traction control built into their brain and body.

Even fast riders on track backgrounds suffer from this.

Marc Marquez, is having his success, because he can out do all the others, in this area.
He trains on dirt..Dirt (and that can be mud, or snow or ice) is a study in throttle control.

Pavement racers may have skipped dirt.

I started in Alaska on ice and snow. Then moved to Oregon, and mountain trails that were more often than not,
slick as snot red clay mud.
You have to go fast, to throw the mud off the tires..
Slow and they pack the mud, filling the knobs, and the mud ball widens to the fork tubes, and stops the wheel from turning, all-together.

Yes, the racers on first gen. ZX-10's, had a problem with traction, rear wheel spin-up, bike coming around.
(could be the start of a highside)

The changes Kawasaki made, to address this, were all changes I didn't want.
Starting with the heavier crank, that slowed down spin-up...To the computer managed electronic management,
Traction control. anti wheelie control, Power reductions when sensors say, trouble is on the way.

Screw that ... there is an alternative...and it is safer.

Rider use your eyes, What is the surface you are on, and what is ahead, coming up.
Use your brain..make your brain tell your body, what to do to tell your bike, what to do.

Without training yourself...working on it all the time to keep it sharp...Your danger/risk, spikes...Don't spike Yourself.
 
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a_broken_record_5000_by_yotrailmix-d303uk7.jpg
 
^^^ Strange how it didn't get heard, with all the playing though...

Riders still do the things that get them killed or mangled...You in favor of that?
 
Lou, It's not the exit that's the hinge part…it's on the entry, where the back chases the front that I've experienced. I've ridden long enough and by far enough bikes (racing and magazine testing) to know what that means…that the wheels don't seem to follow each other around the track. Like I said, fun as hell, but slow as hell too by the clock.

I started off in PA where it's ice and snow and in the dirt there too…that doesn't mean much in this conversation. You keep referring to dirt stuff…I'm not sure you know what speeds I'm referring to.
 
Holeshot said:
Lou, It's not the exit that's the hinge part…it's on the entry, where the back chases the front that I've experienced. I've ridden long enough and by far enough bikes (racing and magazine testing) to know what that means…that the wheels don't seem to follow each other around the track. Like I said, fun as hell, but slow as hell too by the clock.

I started off in PA where it's ice and snow and in the dirt there too…that doesn't mean much in this conversation. You keep referring to dirt stuff…I'm not sure you know what speeds I'm referring to.
Click to expand...

Lol p0wnt.
 
Hooli said:
Lol p0wnt.
Click to expand...

You mean that there might be other riders on here with vast and varied riding backgrounds?

Riders that, gasp, may not think that a 10 year old design isn't the be all and end all of all things motorcycling? :wtf

And those riders actually live in the Bay Area? :laughing
 
Holeshot said:
Lou, It's not the exit that's the hinge part…it's on the entry, where the back chases the front that I've experienced. I've ridden long enough and by far enough bikes (racing and magazine testing) to know what that means…that the wheels don't seem to follow each other around the track. Like I said, fun as hell, but slow as hell too by the clock.

I started off in PA where it's ice and snow and in the dirt there too…that doesn't mean much in this conversation. You keep referring to dirt stuff…I'm not sure you know what speeds I'm referring to.
Click to expand...


Entry, apex, exit...Where ever there is a behavior, is in your control.

If not, it is your doing to put it there. Tweek your set-up or you.
(what ever needs it)

Ya know race teams put the time in at every track...
It isn't we have been here before, check the settings we had last time, set to them, we are ready to go, this time.

Sketchy traction, should mean something in any conversation.
Not meaning much, is a cornerstone in rider/racer problems.

We are talking bike behavior on public road speeds, on this thread, aren't we?

Doesn't this thread, Head with Harley wobbling at 85-90 mph on I-24 East?
 
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