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  #1  
Old 8th May 2018, 10:57 PM
positron positron is online now
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Default Helmet wobble when riding with pillion

Strange problem... perhaps someone can explain this to me.

When I ride with pillion, at over 100kmph, my helmet is getting slammed left and right every other second. It's as if there's someone sitting on my shoulder and slapping my head around. It's violent and totally uncontrollable. I had this when I was on an FZ8 out in Spain with wife, again on FZS600 and today I experienced the same with F800GT. My own helmet (Schuberth SR1) usually cuts thru air smooth - no head wobbles even at 180kmph+ on my own. Tucking in as much as I can helps, but that's not practical on these upright bikes.
What's this black magic? Some sort of air vortex between helmets? Anyone know?

PS: No, it's not her.. She's usually too busy holding on for dear life, and funny enough she doesn't have any problems with helmet. And she noticed my helmet getting kicked around and wondered what's going on.

Last edited by positron; 8th May 2018 at 10:58 PM.
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  #2  
Old 8th May 2018, 11:00 PM
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Gixxer Gixxer is online now
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Default Re: Helmet wobble when riding with pillion

1: Get a helmet that fits.
2: Ditch the pillion.

HTH
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  #3  
Old 8th May 2018, 11:02 PM
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iano iano is offline
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Default Re: Helmet wobble when riding with pillion

You answered your own question
Vortex, turbulence, disturbed air is what causes it
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  #4  
Old 8th May 2018, 11:05 PM
Phaedrus Phaedrus is offline
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Default Re: Helmet wobble when riding with pillion

Originally Posted by positron
Strange problem... perhaps someone can explain this to me.

When I ride with pillion, at over 100kmph, my helmet is getting slammed left and right every other second. It's as if there's someone sitting on my shoulder and slapping my head around. It's violent and totally uncontrollable. I had this when I was on an FZ8 out in Spain with wife, again on FZS600 and today I experienced the same with F800GT. My own helmet (Schuberth SR1) usually cuts thru air smooth - no head wobbles even at 180kmph+ on my own. Tucking in as much as I can helps, but that's not practical on these upright bikes.
What's this black magic? Some sort of air vortex between helmets? Anyone know?

PS: No, it's not her.. She's usually too busy holding on for dear life, and funny enough she doesn't have any problems with helmet. And she noticed my helmet getting kicked around and wondered what's going on.

It is her and yes, it is a vortex.
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  #5  
Old 8th May 2018, 11:08 PM
positron positron is online now
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Biker.ie Member No. 10000 from Drogheda
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Motorbike: F800GT
Default Re: Helmet wobble when riding with pillion

Originally Posted by Gixxer
1: Get a helmet that fits.
2: Ditch the pillion.

HTH
1. Done. SR1 fits like a glove from day 1, and fit is still just as good three years later. Perfect really.

2.
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  #6  
Old 8th May 2018, 11:12 PM
positron positron is online now
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Default Re: Helmet wobble when riding with pillion

Originally Posted by Phaedrus
It is her and yes, it is a vortex.
Originally Posted by iano
You answered your own question
Vortex, turbulence, disturbed air is what causes it
So everyone with pillion riders experiences this regularly? Is there really no way to eliminate it?
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  #7  
Old 8th May 2018, 11:14 PM
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Interceptor Interceptor is offline
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Default Re: Helmet wobble when riding with pillion

Pics of your missus would help with the scientific analysis. Ideally a closeup of her vortex....

'cptr
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  #8  
Old 8th May 2018, 11:47 PM
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NODSTER NODSTER is online now
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Default Re: Helmet wobble when riding with pillion

G'wan giz a gander at her vortex

Joking a side - any feedback from the good lady? Shurely if yer wobbling like a nodding dawg on it's ear, she must be feeling something?
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  #9  
Old 9th May 2018, 12:54 AM
VinnyF VinnyF is offline
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Default Re: Helmet wobble when riding with pillion

I had that issue with the stock screen. Changing to a slightly taller one (Zero Gravity) fixed the problem for me. I still get air flow from mid-chest height on up, but it's a lot smoother.
Hope you get sorted.
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  #10  
Old 9th May 2018, 12:59 AM
Holy Moly Holy Moly is offline
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Default Re: Helmet wobble when riding with pillion

Are you sure you're sure she's not slapping the back of your head ??
Anyways, need a taller or more vertical screen to smooth of the airflow over a larger area - that is you and the mrs, as opposed to just you.
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  #11  
Old 9th May 2018, 08:17 AM
Phaedrus Phaedrus is offline
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Default Re: Helmet wobble when riding with pillion

We're (obviously) disrupting air as we travel through it. Loads of factors affect this stuff - different bikes, different screens, screen position, screen shape, screen height, screen angle, rider height, riding position, pillion vs no pillion, pillion's sitting position, pillion size, road speed...

Have you experienced this buffeting on any other bike with any other pillion?
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  #12  
Old 9th May 2018, 08:56 AM
positron positron is online now
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Default Re: Helmet wobble when riding with pillion

Yep, I experienced the exact same buffetting on a Fazer8 couple of years ago. That was the first time and I thought she was trying to keep her helmet pushed against mine but turned out that she wasn't. Then the same issue on Fazer last year, and now on F800GT. Different bikes, different screens and different helmets even! Always with the same pillion though (hmm.. 'guilty until proven innocent' )

Yes, she can see my helmet getting kicked around, and she doesn't have that problem with her own helmet (which makes me question the air vortex theory..)

Another suggestion I saw online was that it might be because of the rear suspension setting - that with pillion on, the rear is lower, effectively tilting the front screen a bit off the normal position and that's screwing up the air flow. Not sure, but I hadn't adjusted the rear spring for two, so perhaps. I will give that a go this weekend.

Last edited by positron; 9th May 2018 at 08:58 AM.
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  #13  
Old 9th May 2018, 09:02 AM
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Default Re: Helmet wobble when riding with pillion

I often travel with the missus and I never had an issue, she on the other hand had some complaints about turbulence which I fixed via a new adjustable screen and happy days.

Sometimes a smaller screen could be the fix, or winglets, but unless you have a wind tunnel it'll be mostly a trial and error sort of thing as they're too many variables and factors that could affect the airflow.

If it's available to your bike, try screen raisers like MRA which are small, adjustable and not that expensive. They'll give you pretty good flexibility to play around with them.

On my GS I have the Givi Airflow and it's an absolute treat, easy to adjust on the fly and it really, really protects you from the wind.
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  #14  
Old 9th May 2018, 09:51 AM
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Default Re: Helmet wobble when riding with pillion

It's the turbulence in the gap between your helmet and her body (oh er missus...).
When you're solo, the airflow must be reattaching/staying relatively smooth behind your body, but putting the second body in place is changing the flow and giving you the turbulence.

Changing the suspension won't have any effect on it, you'll need to tackle the aero with a higher/lower or differently angled screen - or maybe just get the missus to change her seating position to see if there's a sweet point which eliminates or reduces the buffeting.
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  #15  
Old 9th May 2018, 10:02 AM
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Default Re: Helmet wobble when riding with pillion

Originally Posted by positron
Strange problem... perhaps someone can explain this to me.

When I ride with pillion, at over 100kmph, my helmet is getting slammed left and right every other second. It's as if there's someone sitting on my shoulder and slapping my head around. It's violent and totally uncontrollable. I had this when I was on an FZ8 out in Spain with wife, again on FZS600 and today I experienced the same with F800GT. My own helmet (Schuberth SR1) usually cuts thru air smooth - no head wobbles even at 180kmph+ on my own. Tucking in as much as I can helps, but that's not practical on these upright bikes.
What's this black magic? Some sort of air vortex between helmets? Anyone know?

PS: No, it's not her.. She's usually too busy holding on for dear life, and funny enough she doesn't have any problems with helmet. And she noticed my helmet getting kicked around and wondered what's going on.
..this thread is useless without pictures of said pillion.
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  #16  
Old 9th May 2018, 10:15 AM
motoxyogi motoxyogi is offline
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Default Re: Helmet wobble when riding with pillion

I suspect you're experiencing the Von Kármán vortex street to give it it's scientifical name.
Click the image to open in full size.
When the airflow gets to a certain speed range it starts shedding low pressure vortices from alternating sides of your helmet. These low pressure areas are actually sucking your helmet from side to side. Factors that contribute to it changes according to many variables as some lads have already said. But basically it's due to speed as well as the length, width and aerodynamic shape of your and the pillions helmet.
On the fly you could try to change your speed or the distance between your helmets but I wouldn't expect much. I've experienced the situation with just a hurley handle sticking out of my backpack!
Simplest solution is to do what the others have recommended and get an adjustable windscreen so you're not in the wind.
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  #17  
Old 9th May 2018, 10:28 AM
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The Road Runner The Road Runner is offline
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Default Re: Helmet wobble when riding with pillion

Originally Posted by Gixxer
1: Get a helmet that fits.
2: Ditch the pillion.

HTH
I cant believe the title of this has not been abused...swop out "with" for the...and you have it...
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  #18  
Old 9th May 2018, 10:33 AM
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allsorts&oddjobs allsorts&oddjobs is offline
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Default Re: Helmet wobble when riding with pillion

you could fit a big shark fin on yer lid for a stabiliser like
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  #19  
Old 9th May 2018, 07:56 PM
Caffeine Caffeine is offline
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Default Re: Helmet wobble when riding with pillion

Do you wear the same jocks alone and with her?
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  #20  
Old 13th May 2018, 01:09 PM
faz1 faz1 is offline
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Default Re: Helmet wobble when riding with pillion

Originally Posted by Caffeine
Do you wear the same jocks alone and with her?
That's a very personal question, I'd say none of your business...
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