Tank Slappers

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..

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. I pulled in and had a cup of tea!

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]

Originally Posted by Quiff Wichard

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)

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

[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.

Originally Posted by rictus01

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..