Have you ever experienced the 'high speed wobble'? [Archive] - Glock Talk

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NDGlock
10-24-2005, 09:48
Hey all,

Subject asks it....am curious about it. I've read about it but haven't experienced it yet. Probably because my VTX is no sportbike. I have had it up to 135 w/my feet on the rear pegs and tucked over. It doesn't have a winshield. Everything is stock.

Anyway, I am limited by the V-twin. I suppose I could squeeze what 10 to 20 mph more if I did the commander thing etc.

So, I haven't been going fast enough to experience any loss of control in the sense of a high speed wobble. The VTX is a heavy bike - 704 lbs dry so it really sticks to the road. I like it like that.

That said, do you sportbike riders feel the wobble at 150+?

How do you recover?

fnfalman
10-24-2005, 10:25
Some bikes are more prone to this wobble (aka headshake) than others. If bad enough, it will turn into a tank slapper (the handle bar flapping from side to side hard enough to slap against the tank) and could literally throw you off the bike.

And it usually happens with the sport bikes because they have shorter wheel bases, and with the steering angle on the extreme side. Uneven, bumpy surfaces coupled with high speed would induce headshake. As far as how to get out of it, I think that the only one can do is to slowly easing off the throttle and stiff-armed the handlebar. A steering damper definitely helps.

NMGlocker
10-24-2005, 16:47
On the sportbikes, the wobble usually comes under hard acceleration. The front wheel becomes very light and road irregularities can start it to shaking. It gets worse when the rider tries to fight it. Either stay in the throttle or ease off the throttle, but do not try and fight the shake. Grip the tank with your knees and just try to keep your hands on the bars. If your bike shakes while maintaining a constant speed, something is wrong, either a bent wheel or an unbalanced wheel, or bad steering head bearings.
A steering damper is a good preventive measure, but make sure you aren't using it to hide a defect such as a bent wheel or bad bearings.
I've had some headshake under hard acceleration, but never any while maintaining a constant speed (even up to 176+ mph).

fnfalman
10-24-2005, 17:25
Yeah, I experienced my first headshake just yesterday. It was a strange almost-hairpin downhill decreasing radius turn (thank goodness it wasn't an off-camber turn) that once you rounded the corner, it straightens out into a highway on-ramp. Nobody was around but a bunch of us bikers, so we all took that turn hard. I've never taken this road around and I didn't realize that at the bottom of the curve, just before the straight away, there was a small dip, so I gunned the bike in second gear to thrust out of the corner, hit that small dip and bounced up just a hair. The bike shook the handlebar twice then settled down. I think that since I didn't quite apply full throttle and the bike has a pretty decent steering damper on, it didn't develope into a more serious headshake or tank slapper. But I was like, "what the hell was that?;P "

2cats
10-24-2005, 20:14
I rode through something akin to oil or diesel around a turn at circa 50 - 55 mph (on the Futura). When the front wheel pushed out, I countersteered to tighten my turn. Then the rear went out. Both wheels hooked up, and I thought for an instant I'd made it through, but a tank slapper started. I think I was pretty neutral in terms on inputs. I had time to think "I'm going to the hospital on this one", and then it stopped - all over in a couple of seconds. It was very unpleasant.

I've gotten a quick shake out of both the Futura and Speed Triple at the same spot on Deal's Gap - there's a left hand turn (going south) that opens up onto a nice juicy straight for passing, and when I try to get a jump on it, I get the quick shake.

NMGlocker
10-24-2005, 20:27
I raced motocross for 25 years or so, and played hard and fast in the deserts. On '70's and '80's model dirtbikes you experienced headshake and full blown tank-slappers all the time when you were running fast. A combination of flexible steel frames, cheesy skinny forks, and pogo rear shocks made for some wild rides.
The key to riding a tank-slapper out is to not fight it with your arms, it'll only get worse. Grip the tank tightly with your knees and just try to keep your hands on the grips. Eventually the bike will straighten itself out, and if it doesn't....... you're in for a heck of a wreck.
:cool:

Rinspeed
10-25-2005, 07:17
I lost a wheel weight on one of my Ninja 1000s and it had a nasty shake at around 120. This was just after a new tire was put on. Well I took it back to the dealer and told him to re-balance the wheel as it was very unstable at 120. He just looked at me and said "holy ****, you're not supposed to be going that fast"

steeltoe
10-25-2005, 11:44
My gix has a stock steering damper that works well. Even so I had a wobble through the kink of the front str8 at VIR. Basically a 150mph+ righthand sweeper. Anyways I had a race shop freshen the suspension and bingo, headset bearings needed tightened. No more wobble.

ArmyCop
10-28-2005, 22:10
Which VTX do you have? I'm considering getting a VTX 1800.

BigDeeeeeeee
10-28-2005, 22:37
I've experienced a full on tank slapper at about 110-115 on a buddies early 80s GS850G. Not something I wish to duplicate. I keep from having headshake on my KTM by keeping the front wheel off the ground.;f

BushyAR15
10-29-2005, 07:09
Headshake is headshake. Tank slappers are a whole 'nother story.

Headshake should happen only when you are on the gas hard and the front wheel is just about totally unweighted.

A properly set-up bike should not headshake just because you are going 150+. Down the front straight at the local track you get going in 6th gear topped-out. On any of my racebikes I've never had any shake,wobble, or tank slap at that speed.

The first and foremost cause of headshake is a poorly or an improperly set-up suspension. Most guys buy a bike and just ride without ever giving any thought as to whether or not the suspension is set-up for their weight and type of riding they are doing. Proper "sag" is very important in keeping the balance of the bike under acceleration and braking. I could go on forever on this subject, but I'll leave it at that.

NDGlock
10-31-2005, 12:02
Which VTX do you have? I'm considering getting a VTX 1800.

2004 VTX 1800 C - all stock.

I love it.

http://www.glocktalk.com/showthread.php?s=&threadid=426209



It handles so well and is loaded with torque.

But sometimes, I feel the need, the need for extreme speed and I wonder what a Hayabusa would be like:)

wvwayne
11-15-2005, 01:10
I had a Kaw.750 that would shake at around 130 if you slid back too far on the seat and unloaded the front end,a lot of pucker factor there.;5

fnfalman
11-15-2005, 14:35
The Hayabusa's acceleration is not the explosive sprint like one would feel on a GSXR1000 or ZX10. It pulls strongly and rapidly, and the bike is pretty stable due to the long wheel base and the 500-lbs weight.

Clydeglide
11-15-2005, 20:15
Originally posted by fnfalman
The Hayabusa's acceleration is not the explosive sprint like one would feel on a GSXR1000 or ZX10. It pulls strongly and rapidly, and the bike is pretty stable due to the long wheel base and the 500-lbs weight.

I've been in the auto service biz for over 20 years. I've driven just about every high end high performance car made.

The Hayabusa is the most stable platform I've ever driven/ridden at higher triple digit speeds. It just gets a little breezy over 150 mph.;f The bike does weigh about 550 lbs. wet with full fuel. About the same as the new BMW K1200S/R. The BMW wheelbase is ~4 inches longer than the Busa's 58.5 in wheelbase.

Stable=good.

:cool:

Clydeglide
11-15-2005, 20:18
To answer the question........

High speed wobble.....1973 450 Honda. About 105 indicated......in the rain. Raindrops really hurt at that speed.

:cool: