Tank Slappers

[Quiff Wichard]

hya you clever dudes. no apologiesfor this long question and explanation- I want to get your thoughts in a thread that I can direct the sufferer of a tank slapper to..

went on a long days riding with my local county riders group..

One of the ladies. helen , who rides an 03 R6 and rides it very very well had a major tank slapper on the M6 at about 80mph.. ! and it really shook her up..

didnt witness it as I was in front of her.. which is rare!.
we were last 2 in a group of seven

just noticed she wasnt behind me.. so slowed down and she was tootling (50ish) along.. I thought something mechanical.. so when we all pulled off and stopped at lights she said she thought she was going to die and was clearly upset..


into a lay by and a sit down for her and she was Ok to proceed after 10 mins.. to a hot coffee stop

but- she is worried it was her riding or something to do with her bike>??

so what causes tank slappers.. ? too quick lane change?
hitting a cats eye at 80?..

mefinks it will afect her confidence in herself and her bike and want to reassure her that it aint her fault.. I have never had one.. NEARLY did over that hump on the way to Hawes(norf meets south 06) so I kinda understand the feeling

but no lie- she was white as a ghost. .. !..

and- she is a super rider.. its not a woman thing I assure you.tyre pressures were fine etc etc..

[Quiff Wichard]

ta- 20 views , no comments. ha ha

[RingDing]

It could have been caused by hitting a cats eye I guess. How is her suspension set up? Has she set the sag and the damping appropriately?

When I first put uprated springs in my SV I also uprated the damping oil. Mistake! The high speed damping was already too hard on mye SV and I had two proper tank slappers, not quite lock stop to lock stop but high frequency oscillations where the bar ends moved 4-5 inches. That was due to too heavy damping. I've now fitted emulators to, effectively, soften the high speed damping and I've not had a problem again.

It can scare the wotsit out of you. I had two tank slappers on my LC when I raced it. One was lock stop to lock stop in the middle of the Gooseneck at Cadwell and the front tyre chirped each time the bars hit the stop. :o I pulled in and had a cup of tea! :D

She'll get her confidence back I'm sure.

Is she on an R6 forum (if one exists)? They might have some ideas specific to the R6.

[RingDing]

Does she ride much over the winter? Damping settings that work over the summer will be too hard for the winter as the oil viscosity changes with temperature. If the damping settings are adjustable maybe she could soften it off?

The other thing that could effect it is the headset bearings. Are they too loose or perhaps worn so that they have a bit of a notch in the 'straight ahead' position?

HTH.

[rictus01]

ta- 20 views , no comments. ha ha


Given the lack of information I'm not surprised (long but not detailed).

what had she been doing jus before it happend, would she know what a "tank slapper" is or is that just a generic term she'd use for a lack of control ?
Is the bike modified, what were the road/weather conditions, what speeds were involved, how long has she been ridin that bike ?

the greatest part of learning from these things is understanding what factors could and did effect the ride.

Or are you only after a "this is how a tank slapper happens" type answer ?

Cheers Mark.

[fizzwheel]

On the SV I found the major cause of it was riding hard on a poor / bumpy road surface. The suspension just gets to the point where I cant cope with what the bike and I are trying to do so it gives up and shakes the bars. I've never had the SV tank slap violently though. Normally the bit of road it will do it on is a crest of a hill where the road surface is rubbish and bumpy. if I ride over it with throttle pinned as I bridge the crest the front lifts and oscilates over the bumps and it makes the bars shake every time.

I would have though that the R6 with better suspension didnt oughta do it so badly. My GSXR doesnt, but it has a steering damper. I wouldnt have thought that on the motorway it would do it all. Maybe she rode over something in the road, debris or something like that and it upset the suspension and made it shake / slap the bars ?

Maybe though as you say shes clipped a cats eye and shes changed lane with the throttle open hard and not much weight on the front it might make it do it, but I'm not sure. I'm guessing it might have picked the front up a little and perhaps the wheel wasnt facing the direction that the bike was travelling in when the wheel touched down again as that I think is whats causing it.

Its probably worth getting her to check her tyre pressures, and maybe get if she hasnt the suspension setup properly for her weight ?

Best thing I've found to do is to actually do nothing at all, dont brake, or open the throttle just relax your grip slightly on the bars, stay relaxed try not to sh*t your pants and normally the bike sorts itself out.

I'm not expert on this kind of thing mnd. So I might have got some of this stuff wrong.

[ScottishRawker]

im a noob to biking so can someone explain what a tank slapper is,

(this may also help others like myself when they look at this thread)

Thanks

(edit: Fizzwheel just covered what it is, thanks)

[John 675]

generaly tank slappers ( where the bars shift from left to right at great speed) are caused due to the im balance of ocilation and rotation, if a wheel goes round there is a force that causes it to go from side to side too, think of a shopping trolly wheel as an example, the higher the speed the more rotation per second + ocilation as well, all you need to do is pull one bar to sharp and the inbalance starts but who moves there bars at 80mph?? no one, you went into lean mode 10 mile an hour ago, going over white line and the like causes it too but most stuff is minor and most of the time for seconds at a time untill you get the big one that makes you sh!t your pants, its all to do with thrust / drag / occilation + rotation - or something along those lines i dropped physics

:smt066 :wink: :smt066

[northwind]

If she was going at 80 in a straight line, I'd just rule out the usual light front end + stone/catseye, that only really happens under acceleration. I'd suspect a bad suspension setup or defective part, myself. Every time I've had stability issues it's originated from the back, and R6 shocks have more than enough adjustment to stop them from working.

That's also not a bad place to start if there's been a confidence impact as well- sort of like changing tyres after a lowside, even if they don't make any real difference the placebo effect can be enough! So first things first, I'd make sure the suspension's working right and well set up.

[Quiff Wichard]

Given the lack of information I'm not surprised (long but not detailed).

what had she been doing jus before it happend, would she know what a "tank slapper" is or is that just a generic term she'd use for a lack of control ?
Is the bike modified, what were the road/weather conditions, what speeds were involved, how long has she been ridin that bike ?

the greatest part of learning from these things is understanding what factors could and did effect the ride.

Or are you only after a "this is how a tank slapper happens" type answer ?

Cheers Mark.

Mark - I wasnt pillion !! so i wasnt there..!! so the only info i can furnish you with is what she has said to present- which through the tears wasnt much. and I did say at the outset no apologies for the long explantion..

more edits as I read on.. ... I am after anything that will help helen feel safe to get on her bike again. dunno if tank slapper is a generic term she would use because she's a SHE or not .. would have to ask her.. she's had the bike for about 6 months had an SV before.bike is standard. weather was fine. M6 nice n straight 80mph bit of side wind.

I am only trying to help. then she can read this and get some info..

if it had happenned to me I would ask the same- but able to give more info.. ..

she's registered onhere- but only has a pc at work.. I will text her and get her to give a full detailed account tomoz.,,,










she swears her bars went from lock to lock ??..at 80mph?.. maybe it was slight and felt worse i dunno..

[Alpinestarhero]

Any defects in the road, such as "tracks" where the road has worn down, or a sort of rut that the bike could have got violently pulled into?

If she was accelerating, then a tankslapper is more likley to happen as there is less weight on the front

If it becomes persistant, then softening up the rear end to kick out the forks a bit might make it calmer, at the expense of sharp handling

Matt

[kwak zzr]

Ive never known this at such speed in a straight line? i thought it was on or off the power in a corner or on a uneven surface not a motorway? saying that ive never had one, just a little shake of the head for me.

[Quiff Wichard]

oh she weighs nuffin !.. I have posted pics of her on here before..

here's she bike.

http://i22.photobucket.com/albums/b326/sigourneysbeaver/southport020.jpg

and here's she...

http://i22.photobucket.com/albums/b326/sigourneysbeaver/southport018.jpg

best pic I got-- I got loads of her.. but I assure u this is the best.. :D

[fizzwheel]

she swears her bars went from lock to lock ??..at 80mph?.. maybe it was slight and felt worse i dunno..

Even a small headshake can be quite off putting if your not expecting it.

Mind you if she's saying the bars went from lock to the lock thats really nasty. My brother had that happen on his RS125 when he pushed the bike past its limit. His wrist and thumb were swollen and bruised for days as it slapped quite violently and trapped his hand between the bars and the tank.

I personally think shes ridden over some debris in the road and its made the bike do that. I wouldnt expect it on the motorway...

[sinbad]

Could have been caused by a number of things so obviously check her bike's alright, but the important thing for her to remember (imo) is that she held on to it, she kept it upright, probably purely because she is a good and experienced rider.
Well, at least that's what I would want someone to tell me if my confidence was shot.

[fizzwheel]

Just thinking out loud. If the bike was setup poorly or had a fault, maybe she might have noticed it doing this before but perhaps in a milder way. Has she noticed anything similar before ?

If it was windy today that might have upset the bike. I was out the other week and the wind got hold of the bike and it felt like front was being lifted up and the back was squirming around all over the sodding place. I thought I'd got a puncture the handling was that bad.

[Quiff Wichard]

you are a good bunch ......



I will get her to pop on and explain.. tomoz..

IMO she did bloody well to ride the 100 miles home.. not cos she's a girl.. just cos it took a lot of nerve. she's such a good and confident rider too and not over confident in any way.


I think she might look at the suspension I dunno- will have to see if she says it was set up for her at the dealers. if not- I know her dad is a biker and am sure he would have done it for her weight etc.. sag etc.. but we will see.

[Quiff Wichard]

could ULTRA SEAL cause it?


slopping around inside the tyres..

surely not or it wouldnt get approved would it?

[Toypop]

A stock R6 should not go into a tank slapper on a motorway. So either she was doing something stupid or had done something stupid to the bike...or the bike had done something stupid to itself!

I had the 2004 ZX-6R which is the king of headshakers and it certainly wouldn't go into a slapper like that even when you are d*cking around! I had thousands of headshakers but they were all under max acceleration were all harmless and over in half a second.

I'd seriously give the bike a really thorough inch by inch check.

[Quiff Wichard]

ta for all responses....


please continue

I am sure she will be on here tomoz.. if there aint many folk wanting a mortgage and she's quiet.! ...then you can get it from the horses mouth- as it were.

[BILLY]

Tell her she's got a loverly bum that will cheer her up:wink:

Like the others have said it was proberbly some debree in the road or a cats eye!

[Baph]

On the SV I found the major cause of it was riding hard on a poor / bumpy road surface.

Maybe though as you say shes clipped a cats eye and shes changed lane with the throttle open hard and not much weight on the front it might make it do it, but I'm not sure.

Fizz is exactly right. There's a road I ride a lot on that used to cause tank slappers (not lock-lock, but not far from it) on a certain corner (yes, mid corner!) all the time. Purely because I was riding too hard for the suspension to cope with the road surface. When it's a new sensation is doesn't half put the bejeebus up you. When you're expecting it, it's still a little hairy, but managable.

However, I disagree with the cats-eye theory. I have hit cats eye's at high speed with only a minimal shake, certainly nothing to put an experienced rider to tears over (female or otherwise). I've also hit them under hard acceleration, again, no problems. The only real niggles have been hard on the anchors.

The reason I've used past tense above is because last weekend I was playing with suspension settings. Have a tinker & it does wonders. I now no longer get tank slappers over Pont-y-pass, despite trying my best :oops:

[Fizzy Fish]

Fizzwheel's comments pretty much sum up my own experience/thoughts. Never had any problems with cats eyes or caused by wind though.

Another thought - rider weight may be a contributing factor. I had problems on an Enfield once, couldn't get it over 40mph without getting really bad headshake. funny though when the heavier guys rode it it was fine

[Quiff Wichard]

helen was fine on her curvy..

maybe she needs to have my curvy and I will have her R6.. straight swop.

cheers for comments guys n gals

[Banus]

I've only had one experience of the start of a tank slapper and that was when I was accelerating fairly hard on a slight bend and caught a cats eye - avoid em like the plague now ! It does put the wind up you if its your first experience though !

[Helga]

One of the ladies. helen , who rides an 03 R6 and rides it very very well had a major tank slapper on the M6 at about 80mph.. ! and it really shook her up..
..
Dave...my clock said 125mph when it happened! Was just about to overtake you - think it might have been a combination of too much right hand and changing lanes! Not fun - at all!!! Happened once before on the Horseshoe pass, at 50mph - but that was going over a cats eye. Scared the bejesus out of me then - never mind at 125!!!! I know i know -Stupid girl :(
Gonna TRY not to let it put me off next time....

[Baph]

Dave...my clock said 125mph when it happened! Was just about to overtake you - think it might have been a combination of too much right hand and changing lanes! Not fun - at all!!! Happened once before on the Horseshoe pass, at 50mph - but that was going over a cats eye. Scared the bejesus out of me then - never mind at 125!!!! I know i know -Stupid girl :(
Gonna TRY not to let it put me off next time....
Helga,

On my K6 I've hit cats-eye's around that speed (private road!!), and the only way I'd hit a cats eye is changing lanes.

I still disagree that it was a cats-eye that caused it, lane changes don't get the bike leant over enough (for me at least). Mid corner, esp over a crest, yes, but not cats-eyes.

It'd be worth getting the bike checked over (if you haven't already) if only to put your mind at rest.

[weazelz]

she could always get a steering damper, possibly/probably not necessary, but if that's what it take to get her confidence back it mightn't be a bad investment

[21QUEST]

Right haven't read through all the post so pardon me if I'm repeating what has already been said ;)

Ok...we all know what is tank slapper is.

What causes it? A combination of two or more factors. Primary factors I would class as the following:
Suspension- setting, geometry
Rider-Holding too tight
Bike- maintenance

Cats eyes, bumpy roads etc I'll class as secondary factors.

I'll start by checking the bike over and then putting the suspension back to original settings.

On the SV bad shakes are usually because the rider is holding on too tight. When it gets bumpy. Get very loose on the bike and let the forks do their job. Don't go using 15W and 20W fork oil unnecessarily.
Funnyly enough, just changed my fork oil and used 7.5W:wink:(standard springs on Naked) and it rides great. Not all 7.5W are the same mind :smile:.

Oh...tank slappers can be induced by shutting the throttle as well(but we all knew that):wink:


Ben

[Flamin_Squirrel]

I still disagree that it was a cats-eye that caused it, lane changes don't get the bike leant over enough (for me at least). Mid corner, esp over a crest, yes, but not cats-eyes.

Lean angle has absolutely nothing to do with it though, so it could quite easily be the cats eye.

[Baph]

Lean angle has absolutely nothing to do with it though, so it could quite easily be the cats eye.
The only time I've had even slight wobbles of the bars (and up to almost complete tank slappers), the bike has been leant over. I've hit many a cats-eye with the bike upright, as I've posted before, with no ill effects at all.

Surely that can't be luck though.

Not knowing much about tank slappers, I did a little googling, maybe of use to this thread as a whole:
Now consider what happens when a motorcycle's (http://www.everything2.com/index.pl?node=motorcyle) front wheel (http://www.everything2.com/index.pl?node=wheel) leaves the ground temporarily, such as when the rider pops a wheelie (http://www.everything2.com/index.pl?node=wheelie) or accelerates sufficiently such that full contact of the front tyre with the road surface is lost momentarily. If the wheel is still aligned with the direction of travel when it touches back down there's no problem. In fact, the gyroscopic (http://www.everything2.com/index.pl?node=gyroscope) force created by the rotation of the front wheel tends to ensure this. If, however, the alignment is lost, a tankslapper may happen.
I'd argue that it's harder to keep the front wheel lined up with direction of travel whilst mid corner, partly because the bike is leant over. Probably wrong though.

[Flamin_Squirrel]

Probably wrong though.

As usual, yes.

Search some video of anyone landing a wheelie crossed up to see why.

[Baph]

As usual, yes.

Search some video of anyone landing a wheelie crossed up to see why.

Agreed, wheel is out of alignment with the direction the bike is going. Seen that before.

Like I said though, mid corner, harder to keep the wheel lined up if it looses contact/slips/holding too tight etc. Also the contact patch isn't the same as when straight, so forces through the wheel are changed as well.

Correct me if I'm wrong, but don't most tank slappers happen mid corner? Certainly most of the one's I've seen do. I'm not saying they ALL do though, nor saying that just the corner causes it.

[Alpinestarhero]

Well, i think baph is right. This is my thinking; when a rotating mass (front wheel then) is travelling upright (perpendicular to the plane of the road) and straight then the rotating mass is stable i.e. not prone to oscillations. When that object is lent over slightly (so less than 90 degrees) then the chances of an oscillation of the handlepbars increase (think about how a wheel lent over just wants to keep falling onto its side; and how a rotating wheel lent over wants to go into a spiral) because the rider is trying to fight it. Hit a bump mid-corner and the energy of the rider trying to fight it coupled with the bump setting the wheel stright can induce the tank-slapper. Everyone think waaaay back to the tl1000s, which tank slapped its way through journos like it was a chav seeking an ASBO. This happened alot on bumpy B-roads exiting corners

Now, in addition, when the wheel is off the floor, and rotating, and pointed at some angle away from the line of travel, then when the wheel lands on the floor, the energy of this can cause the unwanted oscillations, since it acts sort of like a spring (the force of the landing straitening the wheel pushes it past the center equilibrium point and to the other side, until the energy disipates).

In both cases, a tank-slapper can occur.

This is my thinking, anyway.

Matt

[thedonal]

I did wonder for a while what tank slappers were- firstly, I thought they were when you come off the revs/brake too hard and slap the delicates on the tank. Was later informed by my bro the true nature of the beast- have to say it'd scare the willies out of me too.

I had concluded, though, that it had nothing to do with very obviously promiscuous ladies and military hardware.

[Flamin_Squirrel]

Well, i think baph is right. This is my thinking; when a rotating mass (front wheel then) is travelling upright (perpendicular to the plane of the road) and straight then the rotating mass is stable i.e. not prone to oscillations. When that object is lent over slightly (so less than 90 degrees) then the chances of an oscillation of the handlepbars increase (think about how a wheel lent over just wants to keep falling onto its side; and how a rotating wheel lent over wants to go into a spiral) because the rider is trying to fight it. Hit a bump mid-corner and the energy of the rider trying to fight it coupled with the bump setting the wheel stright can induce the tank-slapper. Everyone think waaaay back to the tl1000s, which tank slapped its way through journos like it was a chav seeking an ASBO. This happened alot on bumpy B-roads exiting corners

Now, in addition, when the wheel is off the floor, and rotating, and pointed at some angle away from the line of travel, then when the wheel lands on the floor, the energy of this can cause the unwanted oscillations, since it acts sort of like a spring (the force of the landing straitening the wheel pushes it past the center equilibrium point and to the other side, until the energy disipates).

In both cases, a tank-slapper can occur.

This is my thinking, anyway.

Matt

You're overthinking this one...

the wheel is off the floor, and rotating, and pointed at some angle away from the line of travel

That's the only bit that's important, and can happen when you're bolt upright, or lent over.

[21QUEST]

You're overthinking this one...



That's the only bit that's important, and can happen when you're bolt upright, or lent over.

Guys, FS is right you know. No need to overthink :razz: :wink:

[Grinch]

Mmmh slappers...

[Jebiah]

on my ZX6R i had a tank slapper coming over the top of a hill while accelerating hard, front wheel left the floor slightly turned a little bit and hey-presto big ol' tankslapper really is quite scarey :smt103 it can happen in a straight line as much as it can in a corner ...

[Helga]

Thanks for all the advice guys (i'm still a new rider really - only passed in Nov 05) To be honest - i think it's a case of "idiot rider" this time. I'm usually quite sensible aren't i Dave - but everyone was up ahead & i just felt like catchin up. Scared the C*&p out of me though so don't think i'll be doing that again.

And yes - it was proper tankslapping - not just wobbling. My shoulders and forearms are killing me from the bars violently moving about. I'm just really glad someone was on my side on Saturday or else might not be here to ask what i've done wrong.

Feel more than nervous now though (i'm still recovering from a broken back from snowboarding last year - hence the back protector in the pic - cheers for that unflattering pic by the way dave!!)

Anyway -really appreciate your views/tips/advice/comments etc! Big help. Ta muchly. Helen

[21QUEST]

could ULTRA SEAL cause it?


I'll say NO.


Ben

[Quiff Wichard]

Thanks for all the advice guys (i'm still a new rider really - only passed in Nov 05) To be honest - i think it's a case of "idiot rider" this time. I'm usually quite sensible aren't i Dave - but everyone was up ahead & i just felt like catchin up. Scared the C*&p out of me though so don't think i'll be doing that again.

And yes - it was proper tankslapping - not just wobbling. My shoulders and forearms are killing me from the bars violently moving about. I'm just really glad someone was on my side on Saturday or else might not be here to ask what i've done wrong.

Feel more than nervous now though (i'm still recovering from a broken back from snowboarding last year - hence the back protector in the pic - cheers for that unflattering pic by the way dave!!)

Anyway -really appreciate your views/tips/advice/comments etc! Big help. Ta muchly. Helen

soz about the pic...but I cant find a good one of u.??? wonder why?. maybe cos I only take yer bum!..

hey Hells.. maybe ubest change yer signature under the circumstances..????

to.. "HAPPY SLAPPER" ..


OO DOUBLE MEANING IF U KNOW HER BOYS!

[northwind]

The worst slapper I ever had, the front wheel didn't leave the ground at all, and I was going in a straight line... Didn't hit a convenient object either. Just got unweighted enough to get out of shape, and the rapid weighting and unweighting served to set things a wobbling.

My point is that there's no one reason it happens- but hard acceleration's probably most common exiting corners, in road use, so naturally a lot will happen on the way out of a bend.

[21QUEST]

I've only had one proper slapper and that was on a Honda Bros of all things. What I do know was main contributing factor was me mucking around with the suspension.

I'd put in a shock from a different bike and set the chain tension incorrectly. Yours truly did not take into account/forgot the shock had a lot more stroke. Hit a dip in the road and bike went mental :wink:


Ben

[Helga]

hey Hells.. maybe ubest change yer signature under the circumstances..????

to.. "HAPPY SLAPPER" ..

OO DOUBLE MEANING IF U KNOW HER BOYS!

You just wait til i catch up with you next!!!! And yes, stop being a perve takin pics of my @rse!!

[Alpinestarhero]

Guys, FS is right you know. No need to overthink :razz: :wink:

Sorry :oops: I cant help it :(

Matt

[socommk23]

hya you clever dudes. no apologiesfor this long question and explanation- I want to get your thoughts in a thread that I can direct the sufferer of a tank slapper to..

went on a long days riding with my local county riders group..

One of the ladies. helen , who rides an 03 R6 and rides it very very well had a major tank slapper on the M6 at about 80mph.. ! and it really shook her up..

didnt witness it as I was in front of her.. which is rare!.
we were last 2 in a group of seven

just noticed she wasnt behind me.. so slowed down and she was tootling (50ish) along.. I thought something mechanical.. so when we all pulled off and stopped at lights she said she thought she was going to die and was clearly upset..


into a lay by and a sit down for her and she was Ok to proceed after 10 mins.. to a hot coffee stop

but- she is worried it was her riding or something to do with her bike>??

so what causes tank slappers.. ? too quick lane change?
hitting a cats eye at 80?..

mefinks it will afect her confidence in herself and her bike and want to reassure her that it aint her fault.. I have never had one.. NEARLY did over that hump on the way to Hawes(norf meets south 06) so I kinda understand the feeling

but no lie- she was white as a ghost. .. !..

and- she is a super rider.. its not a woman thing I assure you.tyre pressures were fine etc etc..

uneven wear on the front tyre?

loose head bearings?

low pressure in front tyre?

id advice getting a damper big time....i had similar situations...one by uneven wear on tyre and once landing a wheelie on a cat eye!

dampers been fitted and simmilar situ came up trumps for the damper.

it will help her confidence if she has one fitted

and i hope its not put her off.