roadrash
Well-known member
Thank you for a detailed explanation! Makes sense now. Scary thinking about it, not being in control. Hope it never happens to anyone.
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Squid nearly eats asphalt, manages to save it
- Thread starter PrivatePilot
- Start date
J_F
Guest
great explanation MM
aerodynamics can play a role too
my bike is governed at 180 by manufacturer, FJ-09
this is because adding the fairing and screen to the naked FZ-09 introduced instability
I made it worse by putting a large touring screen on it
with the screen in it's highest position, can't get above 160 without a wobble
comes on slowly so there's time to back off, unlike the dude in that vid
aerodynamics can play a role too
my bike is governed at 180 by manufacturer, FJ-09
this is because adding the fairing and screen to the naked FZ-09 introduced instability
I made it worse by putting a large touring screen on it
with the screen in it's highest position, can't get above 160 without a wobble
comes on slowly so there's time to back off, unlike the dude in that vid
I've always understood holding the throttle or throttling out to take more weight off the front end was the best thing to do in this situation.
Yep, you’re correct. The other way will make a better crash video.
Mad Mike
Well-known member
Nope, wrong. There is a very good chance you can't accelerate out, speed increases the wobble. If you're lucky enough to power out, there's a good chance the oscillation returns when you reduce to speed - that gives you a 2 for one experience, always roll off.
In the old days this happened because bikes were crudely designed. Today it's because of some mechanical issue, poor customization, bad maintenance, failed parts. The only late model bike I know of with weave issues is the ST1300, and while deadly it is pretty rare.
Anyone that says to let off the throttle and it will get better has very likely never had a real tank slapper, because you would know that letting off in this situation makes it get much worse. Powering out is your best option....
It even shows in the video, because he let off it got much more violent as his speed dropped and he was very lucky he was able to hold on for the ride....I don't see much skill there I see more luck then anything
That being said getting back on the throttle is easier said then done when the bars are shaking in your hands so violently, and its hard to make getting back on the throttle a natural reaction.
If you want to know what a real bad tank slapper is, its when the bars go lock to lock so hard that if/when you do come out of it, you have no front brakes. The lock to lock is so violent that it pushes your caliper pistons back into the caliper, and you dont have any brakes till you pump them back out in contact with the rotor.....There is a difference between a little head shake and a true tank slapper
It even shows in the video, because he let off it got much more violent as his speed dropped and he was very lucky he was able to hold on for the ride....I don't see much skill there I see more luck then anything
That being said getting back on the throttle is easier said then done when the bars are shaking in your hands so violently, and its hard to make getting back on the throttle a natural reaction.
If you want to know what a real bad tank slapper is, its when the bars go lock to lock so hard that if/when you do come out of it, you have no front brakes. The lock to lock is so violent that it pushes your caliper pistons back into the caliper, and you dont have any brakes till you pump them back out in contact with the rotor.....There is a difference between a little head shake and a true tank slapper
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Ok.
Mad Mike
Well-known member
My guess is you've never had one. I have, a few in fact, none as violent as the one in the video but one close. You might power out of a low speed wobble or head shake at 40kmh, not a high speed wobble.
First, you can't control the throttle, grab brakes or clutch -- if you're lucky you can hold on. There's a good chance the throttle is on and off as the bars slap back and forth, that's likely whey the bloke in the video kept up his speed - he got out by reducing speed. Next, if you do manage to power out, there's a good chance you're going back into the wobble as you reduce speed, again ask anyone who rode a pre 80's ton-up bike. Finally, it the force generated by the back tire that feeds the wobble - you have to get the front tire off the ground to stop it -- good luck with that when the bars are oscillating at 10 slaps per second.
If you want to see how it works, go to a shopping mall and push a shopping cart until you get a front wheel wobble. Push it faster and see if the wobble gets better or worse. Then try slowing down to see what happens. Be interested in hearing your findings!
Iceman
Well-known member
Well, I'm in the throttle out camp. Letting off can definitely make it worse, much much worse.
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I’ve taken the higher level California Superbike School courses a few times and tank slapper recovery is covered in detail. There is also a pretty good write up in Twist2. Unless there is something fundamentally wrong with the chassis they claim Tank slappers are caused by the rider being too tight on the bars and perpetuated by the same.
Code teaches to relax your grip and get your weight a little further forward. I would imagine it’s easier said than done though when you are ******** yourself in the middle of the 401
Code teaches to relax your grip and get your weight a little further forward. I would imagine it’s easier said than done though when you are ******** yourself in the middle of the 401
Maybe I watched a different video, but it sure looks to me like he accelerated briskly when the wobble started, not decelerated. Look how fast he overtakes the bike filming, and the cars.
When in doubt, power out.
Just wanted to chime in- the R6 is the only SS without a OEM stabilizer and I've had a few head wobbles from either rough pavement or the wheel coming back down at a bad angle. Every single one (excluding the first which scared the crap out of me) was easily recoverable by being loose on the bars and applying slight throttle. Chopping the throttle (equivalent to applying brakes) would make the situation worse; you are transferring more weight forward and thus asking for more traction out of your front tire which is already upset.
FattBoyy
Well-known member
Hey guys here is the best video on this subject. It’s Old but real good. If you don’t want to watch it all to learn how and why it happens you can skip to 8:30 to learn what to do
https://youtu.be/fvsDIq3WwVA
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https://youtu.be/fvsDIq3WwVA
Sent from my iPhone using Tapatalk
Trials
Well-known member
Maybe I watched a different video, but it sure looks to me like he accelerated briskly when the wobble started, not decelerated. Look how fast he overtakes the bike filming, and the cars.
When in doubt, power out.
You watched the one I did, looked like he maybe just put the front wheel back down after doing a wheelie which can absolutely induce a speed wobble if your front tire isn't going as fast as the ground is traveling.
Mad Mike
Well-known member
That's a great video, shot on the types of bikes I learned to ride on! Anyone reading this forum ought to be cautious about the 'power out advice'. I'm guessing those posters have never had to get out of a serious weave or tank slapper.
The ones that ride cruisers won't experience a death wobble, they don't go fast enough to overcome the stability of their rake angle. They might see weave, that comes on at high speed if their tires, suspension of bearings are damaged or out of spec.
Most vintage bikes (pre-80s) are susceptible to weave at speeds above 145, only a few will see wobble as they too have rake angles that limit wobble.
Supersports are the most susceptible to wobble, least susceptible to weave. Wobble begins when the front and rear tire become unaligned and the forces exerted on the bike try to get them back into alignment. This can happen due to road hazards, mechanical failure, poor shifting technique, accelerating with one hand on the bars, and coming down off wheelies. Wobbles don't usually come on below 145kmh. Once you're in a wobble, the driving force may be too great for the bike to correct itself so the front wheel oscillates back and forth at it's limits. Reducing the driving force, applying more downforce on the front wheel, and using both hands to dampen steering will all make it possible for the bike to recover.
Hopefully nobody reading this will have to recover. If you ride above 160kmh, it's worth discounting what you read here, go watch the countless Youtube videos on the subject, study the ones that show an actual wobble and recovery, forget the vloggers who mumble their way through like expert.
ps. If you find any videos that show someone power out of a weave or wobble, please post the link here, I'd love to see one!
Mad Mike
Well-known member
Most sport bikes give you a head shake once and a while, their high rake angle does that as it corrects steering when you get your bike out of line. A high speed wobble (tank slapper) is different, it happens when the bike gets to the point where it's can get back with a head shake.
Looking forward to your vlog.
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