Speed Wobbles

[Älen]

Ok today I got my first speed wobble. I was going about 80+ at the time. I did a very small size power wheelie and when the front got back on the ground the bike started to wobble. I did not back of the gas I don't know if that was a good or bad idea, so like I just powerd out of it.

I was shitting bricks after it. So what im asking for is how or what to do when you get hit by wobbles? DId I do the right thing here by not going of the gas? Was I just lucky? Also what did I do wrong to start this?

[BlackFZR]

Front wheel was crossed up when it touched back down. Not having the front wheel straight when you landed caused the front wheel to oscillate from side to side until it straightened out... This is potentially the pre-curser of a tank slapper. On or off the gas doesn't metter too much, its more you don't want to increase the oscillations by adding your own steering inputs into the bike.

Many a tankslapper has lead to a rider being flung off, only to have the bike straighten up and go straight once the rider was no longer trying to add their own inputs into the steering...

Make sure your front wheel is straight when you land a wheelie.

[michael]

ohhh yeah had my first tank slapper on a road bike about 2weeks after i got the ZX10. same deal as yours i spose, small power wheelie coming out of a corner,but shook my ass clean off the seat and ended up in the lane next to where i wanted to be. pretty much shat bricks!

Michael.

[imitch]

Wouldnt it be better to accelerate if the bikes normally wants to straight, that should help straighten out the bike yeh?

[Mo-Fo]

If the front wheel is spazin out then just pop it up again.

Disclaimer - I haven't tried this recovery move myself, might not work

[mantic]

Wouldnt it be better to accelerate if the bikes normally wants to straight, that should help straighten out the bike yeh?

Depends where you have your weight allocated...

Personally if your front wheel is out of shape, you haven't gassed it out properly or placed your body in a decent enough position to ride smooth on or off power!

I would look at your weight distribution and angle of attack with the front wheel before trying to complicate matters further

[filbert]

my first tank slapper was when i was 17 riding my rz500, accelerating hard out of a widening sweeper i ran over a honkey nut with the front tyre and it hopped and wobbled then just whipped side to side so hard i thought it was going to snap my arms, i let go of everything and decided i was going to kick off and dive off the back rather than try to hold onto the bike and get slammed, as soon as my hands came off the bars and my weight went back it straightened itself out, luckily i hadn't parted company too quickly

my 2nd tank slapper, same bike same corner a few days later possibly even the same honkey nut as it started to slap i somehow blipped the throttle in the process and the front end lightened just enough that i had the bars straight as it settled.

neither was a deliberate response so if i had to give any kind of advice it would be don't panic or try to fight it, expect the worst and hope for the best, you're probably already convinced you're going to crash so what do you have to loose by relaxing your grip?

[96]

Push on the bars, open the throttle.

Pushing on the bars turns your arms into dampers, which act to slow the wobble in the bars. It also moves your weight back. Same with opening the throttle.

If your front wheel is light, it can turn in the ground without moving the bike(much) load it up though, and the bike will go were the wheel is pointing.

So, recapping.... Open the gas, if it persists, sit up.

THEN, check your brakes (a bad tank slapped will generate enough g force within the brake calipers to force the pistons back away from the disc, requiring a few pumps to regain braking ability.

[Aufitt]

Ah Filbert I relate to that.. damned 16 " front wheels.
There is some horrific IOM footage of RZ's back in the day.

[Drasius]

Nothing like that little moment of absolute terror when the brakes don't work when you need them too.

[filbert]

Push on the bars, open the throttle.

Pushing on the bars turns your arms into dampers, which act to slow the wobble in the bars. It also moves your weight back. Same with opening the throttle.

If your front wheel is light, it can turn in the ground without moving the bike(much) load it up though, and the bike will go were the wheel is pointing.

So, recapping.... Open the gas, if it persists, sit up.

THEN, check your brakes (a bad tank slapped will generate enough g force within the brake calipers to force the pistons back away from the disc, requiring a few pumps to regain braking ability.

sounds good to me, the worst i've found with the pads knocking off is the reflex to squeeze the lever to the bar as hard as you can and hold as though it's going to help, then if you do have the presence of mind to pump the lever the 2nd or 3rd pump takes up without proper modulation, i once left a skid mark around 5 metres long when i locked the front i thought i was dealing with brake fade but suddenly the brakes took up as though someone jammed a stick through the spokes.

[Noctis]

So shifting the weight off the front wheel is key.
This raises question on what I thought about older bikes without steering dampers.
How's the dynamics of that work then if accelerating on those bikes is what actually induces a tank slapper due to less weight being on the front wheel?

I dunno, they just kinda contradict each other. (unless I'm wrong about that statement about older bikes in which case that make sense to me haha)

[96]

a slapper is typically induced when the wheel is in limbo, between on, and off the ground, just kinda sliding along. (that, or landing crossed up)

once it starts though, you dont want it to direct the bike, hence moving weight back.

make sense?

[mantic]

So shifting the weight off the front wheel is key.

Yes in some situations!

This raises question on what I thought about older bikes without steering dampers.

Why?

How's the dynamics of that work then if accelerating on those bikes is what actually induces a tank slapper due to less weight being on the front wheel?

They don't!

I dunno, they just kinda contradict each other. (unless I'm wrong about that statement about older bikes in which case that make sense to me haha)

It's black magic...

[filbert]

it's black magic and geometry, the steeper the fork rake and the shorter the trail/smaller wheel the more likely and the more violent a tank slapper will be IMHO and based on experience.

ever seen a harley get the slaps? they will flick from side to side fairly violently as the rider overcorrects each action but it's never the full on shopping trolley wheel style whip you get on a sports bike, case in point shopping trolley wheel, it's a steep rake the axle of the wheel is not far behind the steering pivot but even the fact that it is behind rather than in front is part of that faulty geometry, get a bit of speed into a shopping trolley that has most of the weight off of a front wheel and you'll see it all in action.

even bicycles have a proven formula for rake and trail and their relation to wheel sizes to provide a stable platform, the more the rake the slower the steering but the higher the stability, larger wheels mean you can change other variables, if you were to set up a completely vertical fork with the axle through the base providing zero trail you would have the ultimate tank slapper demonstration model and most likely head injuries from the test ride when you threw yourself into the bush.

[JamieBlade]

sounds good to me, the worst i've found with the pads knocking off is the reflex to squeeze the lever to the bar as hard as you can and hold as though it's going to help, then if you do have the presence of mind to pump the lever the 2nd or 3rd pump takes up without proper modulation, i once left a skid mark around 5 metres long when i locked the front i thought i was dealing with brake fade but suddenly the brakes took up as though someone jammed a stick through the spokes.

Don't feel too bad, Casey did similar last year at Motegi!

[Noctis]

Yes in some situations!

Why?

They don't!

It's black magic...

Thank you. I now feel like I can take on the world with the information gained from your very insightful and in-depth post.*

[Crim]

I parked my '99 R1 in a ditch up in the Chittering valley many years ago thanks to a nasty head shake & loss of front brakes. After this experience I promised myself I would never own a sport bike without a steering damper. I have never had an issue since then on a number of different models thanks to Ohlins.

[Älen]

Don't really have the money to buy a steering dampener at this point in time.

[Rat750]

Nothing like that little moment of absolute terror when the brakes don't work when you need them too.

Calling Ozboy