Speed wobble, should I be worried

[catzo]

Hey,

Just got a 2005 fz6 the other week, 30k kms, never dropped. Love the bike, looking forward to being part of this community. Anyways....

On my 3rd or 4th ride I almost lost control when the front wheel began to wobble extremely violently during hard acceleration. Luckily I backed off the throttle and was able to regain control. I was accelerating hard to pass a car, probably went from 100km/h-160km/h during the pass, accelerating full out, over a really really bumpy road. Imagine the most uneven road youve ever seen, that was this road.

So I'm wondering if this is something I should be worried about, I've heard of some people saying it could be caused by an old wheel bearing or bent forks, but the bike hasnt been dropped as far as i can tell. The bike has been sitting though as the previous owner only put 2500kms on it in 3 years (I consider that sitting)
Or was it just caused by what I was doing, accelerating too hard over a really bumpy road? My old bike was a ninja 250r so I never really had the problem of speed wobble.

Any thoughts? Even just suggestions on things I should be looking at.

 

[Serzedo]

It could be because of the road that made the front wheel to start to go up because of the acceleration, but it could be the tyres too... just my guess.

"V"

 

[catzo]

ya the front wheel was definitely going up a bit. It couldve just been catching on the bumps in the road. Still, its stored away now so I have all winter to tinker with it. Would gettimg the wheels balanced do anything you think? I could just replace the whole wheel.

 

[TownsendsFJR1300]

ya the front wheel was definitely going up a bit. It couldve just been catching on the bumps in the road. Still, its stored away now so I have all winter to tinker with it. Would gettimg the wheels balanced do anything you think? I could just replace the whole wheel.

+1 on too much throttle for conditions.

The front wheel is getting light and your loosing your steering

How does it behave while cruising (even at high speed) or on de-deceleration? Any real issues would show then. Please post any other symptoms (if there are) OTHER than hard acceleration on a rough road...

An out of balance wheel will wobble, vibrate thru the handlebars all the time at a certain speed. Its easy enough to do a static test/balance. It should be balanced (as well as the rear) in any case for long life and to prevent any wobbling..

***BTW, your fixing to have your first lay down riding like that in those particular conditions...

 

[Motogiro]

If you were accelerating enough to lift the front wheel or almost lift it you can get wobble just as the wheel transfer it's contact from the road or back to the road. The other things are pretty much covered and don't forget about tire pressure!

 

[catzo]

+1 on too much throttle for conditions.

The front wheel is getting light and your loosing your steering

How does it behave while cruising (even at high speed) or on de-deceleration? Any real issues would show then. Please post any other symptoms (if there are) OTHER than hard acceleration on a rough road...

An out of balance wheel will wobble all the time at a certain speed. Its easy enough to do a static test/balance. It should be balanced (as well as the rear) in any case for long life and to prevent any wobbling..

***BTW, your fixing to have your first lay down riding like that in those particular conditions...

It does feel like there is some light wobble at higher speeds. I wouldnt even call it wobble, just, not perfectly straight and steady all the time. That one time was the only time it was significant.

And ya I realize now it wasnt smart. I remember being told not to do that in riding school but riding a ninja 250 made me forget that rule. Theres almost no condition where you couldnt ride that full out. Picked up some bad habits that wont translate well to a bigger bike that i'll have to correct. Don't worry, this incident definitely scared me straight. I'll be alot more careful now.

 

[FinalImpact]

Adding to all of the above; as the nose gets light it is now up the rider to maintain equal pressure at both grips so as to maintain symmetry and NOT move the bars. The issue is once the road is not pushing on the tire (yes i said it that way on pupose), the bikes "input" function changes as the steering (rotational action) has nothing to work against. So its mostly the rider that initiates the imbalance which starts the event of you vs the bike.
The bike will win every time!

Point: when it gets light, don't try to fix it as it can end very badly... And work on loosening up so there is no death grip on the bars. It will save you when sh$t hits the fan!

 

[payneib]

Things that make my front end misbehave:

HARD acceleration. The nose gets light, and the wheel reacts to any inconsistencies in the road surface.

Cross winds. It's nasty feeling them snatch at the front wheel.

Worn front tyre. It just feels weird.

From the sounds of it, you had a little a skip of the front wheel while being a little "enthusiastic". Get some more experience and you'll be aiming for that reaction. Just take it steady until you're settled in.

Sent from my E5823 using Tapatalk

 

[steve.getsiv]

I would check the balance on the front wheel. A static balance machine is pretty cheap and very useful - or you can make one yourself. Find the heavy side of the wheel and add some weight(s) on opposite side. Check bearings for play as well. If the tires are old, say 4+ years, they should probably be replaced.

 

[JJS209]

sounds like "normal" kickback/tank slapping for me.
when i had it the first time it was on the autobahn with my rj15 while i was doing >220km/h over a bridge.
in this sitation it was caused by the expansion joints/seams of the bridge (winter-summer temp. differences...) that were like a big bump.
while i had the throttle wide open my front wheel was a little bit lifted by that bump and by retouching the surface it was just a little bit steered and the effect of "jumping" from one side of the tyre to the other caused that tank slapper/kickback/steering wobble effect.
the next day i bought a steering damper, better for the neves.


maybe i am wrong but for me personal it happens from time to time while i am riding fast on the AB.
on the track it is very useful to have steering damper IMO.
on the other side, i will not buy one for may '05 Fazer.
its just too expensive and with some expierence you can handle sitations like that. (sorry for my ger.english)

 

[TownsendsFJR1300]

sounds like "normal" kickback/tank slapping for me.
when i had it the first time it was on the autobahn with my rj15 while i was doing >220km/h over a bridge.
in this sitation it was caused by the expansion joints/seams of the bridge (winter-summer temp. differences...) that were like a big bump.
while i had the throttle wide open my front wheel was a little bit lifted by that bump and by retouching the surface it was just a little bit steered and the effect of "jumping" from one side of the tyre to the other caused that tank slapper/kickback/steering wobble effect.
the next day i bought a steering damper, better for the neves.


maybe i am wrong but for me personal it happens from time to time while i am riding fast on the AB.
on the track it is very useful to have steering damper IMO.
on the other side, i will not buy one for may '05 Fazer.
its just too expensive and with some expierence you can handle sitations like that. (sorry for my ger.english)

Wish we had an autobahn to play on!!!!

Your English is fine.

Ich ben Sprenchen Deutch nicht zer gut! (high school German...)

 

[catzo]

I would check the balance on the front wheel. A static balance machine is pretty cheap and very useful - or you can make one yourself. Find the heavy side of the wheel and add some weight(s) on opposite side. Check bearings for play as well. If the tires are old, say 4+ years, they should probably be replaced.

I do most of my own maintenance but I have no idea how to balance a wheel and wouldnt trust myself doing it. The previous owner had records of the rear tire being replaced 2 years ago and it still looks pretty new. The front tire is from before the last owner (he had it for 3 years) so I have no idea how old it is. So I'll probably replace that. Anyone know what that usually cost?

sounds like "normal" kickback/tank slapping for me.
when i had it the first time it was on the autobahn with my rj15 while i was doing >220km/h over a bridge.
in this sitation it was caused by the expansion joints/seams of the bridge (winter-summer temp. differences...) that were like a big bump.
while i had the throttle wide open my front wheel was a little bit lifted by that bump and by retouching the surface it was just a little bit steered and the effect of "jumping" from one side of the tyre to the other caused that tank slapper/kickback/steering wobble effect.
the next day i bought a steering damper, better for the neves.


maybe i am wrong but for me personal it happens from time to time while i am riding fast on the AB.
on the track it is very useful to have steering damper IMO.
on the other side, i will not buy one for may '05 Fazer.
its just too expensive and with some expierence you can handle sitations like that. (sorry for my ger.english)

All i know about the autobahn I learned from jeremy clarkson. Apparently even at 200km/h youll still have businessmen in audis tailgating you and german trucks pull out into the left lane without looking- Clarkson 3:14





All your replies are making me think it probably was just my actions in those conditions that caused this, which gives me some peace of mind. I have half expecting to hear "your forks are bent and the bike is going to catch fire and explode at any second" or something along those lines

 

[JJS209]

these effects can also be caused by a not acurate installed or defective steering bearing.
i will replace mine this winter (~15.000 km).
but we have 12°C here in hanover. normal would be somthing near or under 0°C.
absolutly amazing for riders weather, a little bit strange but warm

P.S. the autobahn isnt such a wonderful thing. yes you could go fast and make 400km in two hours but its totaly exhausting on a bike and uncomfortable.
i ride every month 400km to the neatherlands and back to my gf but if i have the chance to take a car, i do it.
on the other side its very nice to travel fast with a car, its comfortable, its save and there is no stress even if you drive >200km/h (if possible). its just training/usualness.
nice example with the trucks, i had a situation like that: costs me over a dozen of broken bones and other sh*t... so its, as well from time to time a dangerous thing.

 

[FinalImpact]

I'm pretty sure you can fit it with new tires, balance them, replace harware and return to the scene and replay that maneuver and get the same results.

A steering damper will help add resistance so the rider input takes effort which reduces how much you get the front OUT of Alignment with the rear that creates the issue when steering is light...

Do this while parked; block the nose up and take your rider position. Twist the throttle, apply the brakes, pull the clutch. Watch how much you inadvertently move the bars without meaning too. That can easily initiate what happens when the nose gets light. Its great reason to practice floating your hands on the grips. It teaches you to loosen up and let the bike take care of itself.

JM2C!

 

[gonnacrash]

Google dyna beads for the balancing issues. I cheated and put number 8 lead shot in my tires on my old bike when I did the tires.worked great

Next the worse thing you can do for a speed wobble is slow down, accelerating thru the wobbles is the best thing you can do. As well as a loose grip and dont fight it. Now I don't mean all out, holy cow I am doing 130 mph. Just a steady acceleration

 

[catzo]

Next the worse thing you can do for a speed wobble is slow down, accelerating thru the wobbles is the best thing you can do. As well as a loose grip and dont fight it. Now I don't mean all out, holy cow I am doing 130 mph. Just a steady acceleration

Even if that is technically true, if it ever happens again i would definitely do exactly what I did.

I went from "im definitely going to crash" to "im totally fine" the second i backed off the throttle. The instant I backed off the throttle the wobble stopped. So backing off the throttle worked perfectly for me.

I rode my ninja 250 to the gas station today to fill it up with fuel and fuel stabilizer for the winter, and I see why I never had this problem on that bike. The thing literally has zero power. I used to think i was so fast. Now it feels like a toy.

 

[gonnacrash]

The important thing is don't panic. So you did good there.

As for why accelerating works.
We all know if we lower the front end it changes the rake, which lowers the stability. Now quickly slowing down lowers the front end and raises the rear doubling the rake issue. Now a gentle off throttle is one thing, panicking and hitting the front brakes hard is totally different. Also using the rear brake does not cause the front end to dive as much.

 

[ChevyFazer]

Always power out of a speed wobble, slowing down loads the fronts suspension and can intensify the wobble. Also get that front tire replaced asap, sounds like it could be 6+ years old that's likely the main issue. If you do it yourself just look for the paintedspot on the tire and line it up with your valve stem and boom instantly balanced as long as no wheel issues. Been doing it for years and never had a tire balance issue

 

[catzo]

Always power out of a speed wobble, slowing down loads the fronts suspension and can intensify the wobble. Also get that front tire replaced asap, sounds like it could be 6+ years old that's likely the main issue. If you do it yourself just look for the paintedspot on the tire and line it up with your valve stem and boom instantly balanced as long as no wheel issues. Been doing it for years and never had a tire balance issue

Did I mention this happened while I was accelerating full out?? For those saying I shouldve accelerated out of it, I appreciate your help but how do you accelerate out of something when that something happens at a point where the throttle wont twist any further? It was either, keep doing what im doing or back off the throttle. Sorry, I just had to point that out.

I've never brought a bike to a shop...well, except to get it safetied. But I don't trust myself to put a wheel on and balance it. I'll probably ask some friends and relatives that ride for a trusted mechanic that hopefully can do a friends discount and bring it in in the spring. Seems like a smart thing to do.

the important thing is don't panic. So you did good there.

As for why accelerating works.*
We all know if we lower the front end it changes the rake, which lowers the stability. Now quickly slowing down lowers the front end and raises the rear doubling the rake issue. Now a gentle off throttle is one thing, panicking and hitting the front brakes hard is totally different. Also using the rear brake does not cause the front end to dive as much.

thanks, good to know i did something right haha. Thats exactly what I did, I didnt panic, didnt go for either brake, just slowly backed off the throttle. Actually I probably loosened my grip on the bars too, although it was just because I could barely hang on to them.

 

[TownsendsFJR1300]

Just as a side, many moons ago, I was assigned to a police traffic motorcycle (Loaded Harley with big wind screen, etc).

I was chasing down a speeder and once the bike hit about 100MPH, it got very unstable, just shy of a tank slapper, (smooth road). There was no more throttle (aerodynamic;s like a brick). Gently backed off the throttle and was fine, just the limits of the bike.

In your case, I don't think there's anything wrong with your bike, just too much throttle for road conditions...