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 Motorcycle Safety
 Technical/Maintenance
 High Speed Wobble
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johncrosby
Male Senior Member
256 Posts


Sevenoaks, Kent
United Kingdom

BMW

GSA 90 Anniversary

Posted - 07/06/2013 :  2:23 AM                       Like
I'm the proud owner of a new bike (90th anniversary edition BMW R1200GSA) and have noticed some oscillation of the front shocks at speed. It's a slowish slight shimmy , it doesn't seem to travel up to the bars.

My concern is suffering a tank slapper. I'm getting a bit paranoid about especially after the UK bike journalist Kevin Ashe died test riding the new liquid cooled GS earlier this year.

So my technical questions (sorry for the preamble I do get there eventually).

Will a properly set up suspension (this bike has ESA and is set up for 1 rider plus luggage preload and normal damping) always exhibit some lateral movement of the front shocks or should they be absolutely static apart from their vertical shock absorber movement?

I could just be noticing something I really shouldn't bother about but it only occurs at high speed, above 70mph. It's not progressive, just maintains this slight movement. If you look at the top of the two shocks they appear to be moving a few degrees clockwise in a circle, then back again anticlockwise and so forth.

My useless BMW dealer isn't interested, probably thinks I'm mad to worry about these things.

Could fitting a steering damper (or is it dampener?) be a solution or insurance against anything like a real tank slapper happening.

Best regards

John

Edited for terrible spelling and grammar.

Edited by - johncrosby on 07/06/2013 9:15 AM

greywolf
Male Moderator
1492 Posts
[Mentor]


Evanston, IL
USA

Suzuki

DL650AL2

Posted - 07/06/2013 :  8:22 AM
A steering damper is excellent insurance against a tank slapper. I lived through one that threw me off and I feel much better riding with a damper. It stops large, high speed displacements but not the little wiggles you report. I would check the model specific forums about that if I were you.
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rkfire
Advanced Member
1689 Posts


Stratford, CT
USA

Suzuki

Bandit

Peer Review: Blocked

Posted - 07/06/2013 :  11:06 AM   Join poster on Facebook as Friend  
Something seems off to me. The telelever forks are designed to be supported, and fixed in position better than convenional forks. There is only the one shock and spring, so there should be no difference from one leg to the other.

Seeing any movement at all laterally or at the top at the triple tree would cause me concern. It sounds to me like things aren't tightened up properly, and to spec.

Find another dealer, that will actually take a look, and check the torque at all the front end bolts.
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scottrnelson
Advanced Member
6886 Posts
[Mentor]


Pleasanton, CA
USA

KTM

990 Adv, XR650L

Posted - 07/06/2013 :  12:23 PM
Is there any chance this is related to a front tire that is out of balance?

I just noticed that my KTM gets some unwanted vibration from a mis-balanced front wheel when above about 90 mph.

I already know that the answer is that I shouldn't be riding that fast, but sometimes you just have to get around traffic to get to the big gaps where it's safer.

I'm due for some new tires on that bike anyway, so it will be fixed soon, one way or the other.
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