Speed wobble

[Flipfly]

I’m new to this Hexhead world, but I’m old enough to know something isn’t right with my bike.

Up to 80mph the bike is smooth, no issues, after that it gets a pronounced wobble (85+). It almost feels like a combination of it surging and a wheel being out of balance (having never had a bike wheel out of balance it’s hard to comment on whether it is or not), but with a car tyre out of balance you can normally drive through it, this continues to get worse.

I’m going to get the balancing checked, but is there anything else that strikes a chord with anyone?

oh, and my pressure sensors are on the blink, both seem to be intermittent……is there a cheap cure or is it a replacement job?

Thanks for any advice

 

[oblertone]

Old but gold

https://youtu.be/fvsDIq3WwVA

 

[oddshapedballs]

Have you checked the torque of the front and rear wheels, do you have the panniers on and have you got a load of weight in one and not the other, how old are the tyres - if you have a local tyre fitter it'll be worth having him remove the wheels, check to make sure they're running true and then re-balance.

Cast or spoked wheels?

Re: tyre pressure sensors - once they go they go, there isn't a fix other than replacing with new.

 

[Flipfly]

Old but gold

https://youtu.be/fvsDIq3WwVA

Tyre pressures are spot on

Have you checked the torque of the front and rear wheels, do you have the panniers on and have you got a load of weight in one and not the other, how old are the tyres - if you have a local tyre fitter it'll be worth having him remove the wheels, check to make sure they're running true and then re-balance.

Cast or spoked wheels?

Re: tyre pressure sensors - once they go they go, there isn't a fix other than replacing with new.

No panniers, same with or without top box.

Tyres are in very good order so I can’t see that being an issue.

Haven’t checked the torques tbh, but I’m going to drop it in to Steve at F&B to check the balancing, so they will be done at the same time.

I’ve looked and you can try replace the battery in the Tpms so might give that a go before spending a ton of cash.

 

[Slipperyeel]

I've just arrived into a hot Italy. My bike does a similar thing to what you describe, but at much higher speeds, notably around 160kmh.

I posted something similar about a year ago. I was able to bring it on, on demand. Backing off the throttle gently cured it. I should mention this is loaded with panniers, top box, no pillion.

Since then I have had the suspension fully serviced by Denz0 in here and it's like a new bike. So I suggest you seriously consider a suspension refurbishment. It will likely transform the bike.

On this trip to return my son and I were v close to the payload limit. My son has grown a lot and is essentially the size and weight of another reasonably sized adult. Additionally the panniers were a tad over what I like to have them at (had to bring more of his stuff - Brexit had made it might impossible to post things now). I did weigh everything carefully and not Inc the bike and fuel, we were about 5kg off the limit described in the handbook.

So this time I was conscious of the change, so was 'listening' carefully to the bike. What I found was I had a new vibration that came in on a slow frequency at around 130kmh, it was like rhythmic purr that took me some miles to work out it actually was the bike and not the wind (which I find can generate a vibration depending on what angle is coming in at). I tried to see if I could ride it of this rhythmic purring and it did seem to smooth out a tad at about 145-150kmh, but it hasn't disappeared. Interestingly, at those speeds, no hint of an impending wobble. So as per the video, weight is clearly a factor.

In the end, the GS is not a fast bike and not particularly aerodynamic! It will be limited in the max speed dept.

Sorry, bit of a long reply! But it might be useful, since I've just stepped off the bike, it's all fresh in my mind!

Sent from my SM-G975F using Tapatalk

 

[Flipfly]

I've just arrived into a hot Italy. My bike does a similar thing to what you describe, but at much higher speeds, notably around 160kmh.

I posted something similar about a year ago. I was able to bring it on, on demand. Backing off the throttle gently cured it. I should mention this is loaded with panniers, top box, no pillion.

Since then I have had the suspension fully serviced by Denz0 in here and it's like a new bike. So I suggest you seriously consider a suspension refurbishment. It will likely transform the bike.

On this trip to return my son and I were v close to the payload limit. My son has grown a lot and is essentially the size and weight of another reasonably sized adult. Additionally the panniers were a tad over what I like to have them at (had to bring more of his stuff - Brexit had made it might impossible to post things now). I did weigh everything carefully and not Inc the bike and fuel, we were about 5kg off the limit described in the handbook.

So this time I was conscious of the change, so was 'listening' carefully to the bike. What I found was I had a new vibration that came in on a slow frequency at around 130kmh, it was like rhythmic purr that took me some miles to work out it actually was the bike and not the wind (which I find can generate a vibration depending on what angle is coming in at). I tried to see if I could ride it of this rhythmic purring and it did seem to smooth out a tad at about 145-150kmh, but it hasn't disappeared. Interestingly, at those speeds, no hint of an impending wobble. So as per the video, weight is clearly a factor.

In the end, the GS is not a fast bike and not particularly aerodynamic! It will be limited in the max speed dept.

Sorry, bit of a long reply! But it might be useful, since I've just stepped off the bike, it's all fresh in my mind!

Sent from my SM-G975F using Tapatalk

Suspension is wilbers esa stuff and all works as should, but worth pondering if the balance is out.

Not looking to do 100mph everywhere, but a steady 80-85 really, 80 is fine 85 is not.

 

[Slipperyeel]

Suspension is wilbers esa stuff and all works as should, but worth pondering if the balance is out.

Not looking to do 100mph everywhere, but a steady 80-85 really, 80 is fine 85 is not.

Sounds like suspension is off the list then.

Not sure what else it might be. Check wheel balance next?

I'm also not doing 100mph everywhere. But like you, the 70-80mph bracket is preferable range.

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[mikeyboy]

What tyres are fitted

 

[AustinW]

Tyre pressure sensors…. Replace the batteries. Relatively easy, there’s a sticky guide on the site somewhere. That’s what I followed. Getting the tyres off is the hardest part. If I can do it anyone can. I used a hot glue gun that cost £4.99 to seal them up.

Handling, I used to load my GSA waaay past it’s weight limit and it was fine at any speed. Wilbers suspension specc’d for our weight though. If handling and ride is ok in all other circumstances except 85+ then I would be suspecting tyres/pressures. Head bearings or something else at the front maybe too.

Out of balance front wheel feels like a pulsing right through the bike. In my experience noticeable at around 40mph (onset prob depends on how out of balance) and getting worse the faster you go until it sort of disappears, I suppose it’s vibration by then. A rear must need to be miles out of balance as I’ve never noticed anything despite having owned lots of bike where I have replaced dozens of tyres and never balanced the wheel.

Good luck sorting it.

 

[Flipfly]

I’ve just had a set of A41 Bridgestones fitted and they have definitely improved it, but my Harley is smoother at 90!

I suspect there is a little imbalance in the engine also, as it’s now not a wobble, but there is still quite a lot of vibration.

Tbh, it’s rare that I do over 85 so I’m happy to live with it.

The old tyres were actually a bit worse than they looked as they had loads of tread, but they had cupped quite a lot (they were Dunlop road smart (2 or 3’s can’t remember!).

A41s feel planted and much better suited to the bike (I had A40s on the 1150).

Tyre pressure monitors sprang back in to life and then went off again

 

[AustinW]

Definitely a sign of weak batteries on TPMS when they work sometimes not others. Sooner or later they’ll only work on warmer days then only sometimes on warm days before stopping working altogether.

 

[Slipperyeel]

Tyre pressure sensors…. Replace the batteries. Relatively easy, there’s a sticky guide on the site somewhere. That’s what I followed. Getting the tyres off is the hardest part. If I can do it anyone can. I used a hot glue gun that cost £4.99 to seal them up.

Handling, I used to load my GSA waaay past it’s weight limit and it was fine at any speed. Wilbers suspension specc’d for our weight though. If handling and ride is ok in all other circumstances except 85+ then I would be suspecting tyres/pressures. Head bearings or something else at the front maybe too.

Out of balance front wheel feels like a pulsing right through the bike. In my experience noticeable at around 40mph (onset prob depends on how out of balance) and getting worse the faster you go until it sort of disappears, I suppose it’s vibration by then. A rear must need to be miles out of balance as I’ve never noticed anything despite having owned lots of bike where I have replaced dozens of tyres and never balanced the wheel.

Good luck sorting it.

Interested in your comments on front wheel balance. I have new tyres (though this is now their third run to Italy - they were brand new for the first leg) the weather was crap on the first two legs, so I'm wondering if in the shitty weather melee, I didn't notice the rhythmic vibration. Quite possible. I'm going to check the front and see

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[botus]

to quote normal BMW dealer response to any issue

they all do that sir
or
its a design feature

multiple features help give this behaviour

the type / manu and angle of the screen
the size and clothing of the rider
not having the adventure winglets - if you read the blurb, its to reduce strange air flow smashing into your kidneys
the type of crash helmet - I have a suomy lid (expensive posh modern looking full face lid - that you can't use on a GS or you can't see where you are going)
the luggage fitted - air likes flowing round gentle curves, sticking massive slab sided bits out in the airflow will do things - top boxes cause this get used to it
the tyre brand and type - alongside tyre profile (a worn squared off rear will acerbate) - tyre pressures etc.
seized or too stiff rear suspension
fender extender front mudguard - catches the breeze and as the top box its already trying to lift the front it makes the wobble livelier
wheel balance - according to Dunlop, dynamic balance doesn't impact bikes - I disagree - although the wider the tyre the more the effect. normal balance issues circa 62mph and dynamic is 85mph

But perhaps the reason you notice it more than most on these bikes is the way BWM build in manoeuvrability - these things change direction like hoodie bike thief riding a 125 on acid - and this is far more fun than worrying about needing 8 foot of road rather than the 4 foot you need with a Honda

with 40kg in my overloaded givi treker outback 62 litre top case at 120mph its all over the place - who cares, its never builds just meanders a bit - a top tip in all but one motorcycling riding situation - relax and just keep it nailed. The only time to reverse very very fast out holding it nailed is when a massive violent weave starts usually quite slow speed (60 to 90) and just tells you its game over straight away - never attempt to power out of these - just kill the throttle and get on the brakes - or you just come off at a higher speed. I don't think any air-cooled GS can do lock to lock stop and throw the rider on the floor (unlike the LC's).

 

[Slipperyeel]

to quote normal BMW dealer response to any issue

they all do that sir
or
its a design feature

multiple features help give this behaviour

the type / manu and angle of the screen
the size and clothing of the rider
not having the adventure winglets - if you read the blurb, its to reduce strange air flow smashing into your kidneys
the type of crash helmet - I have a suomy lid (expensive posh modern looking full face lid - that you can't use on a GS or you can't see where you are going)
the luggage fitted - air likes flowing round gentle curves, sticking massive slab sided bits out in the airflow will do things - top boxes cause this get used to it
the tyre brand and type - alongside tyre profile (a worn squared off rear will acerbate) - tyre pressures etc.
seized or too stiff rear suspension
fender extender front mudguard - catches the breeze and as the top box its already trying to lift the front it makes the wobble livelier
wheel balance - according to Dunlop, dynamic balance doesn't impact bikes - I disagree - although the wider the tyre the more the effect. normal balance issues circa 62mph and dynamic is 85mph

But perhaps the reason you notice it more than most on these bikes is the way BWM build in manoeuvrability - these things change direction like hoodie bike thief riding a 125 on acid - and this is far more fun than worrying about needing 8 foot of road rather than the 4 foot you need with a Honda

with 40kg in my overloaded givi treker outback 62 litre top case at 120mph its all over the place - who cares, its never builds just meanders a bit - a top tip in all but one motorcycling riding situation - relax and just keep it nailed. The only time to reverse very very fast out holding it nailed is when a massive violent weave starts usually quite slow speed (60 to 90) and just tells you its game over straight away - never attempt to power out of these - just kill the throttle and get on the brakes - or you just come off at a higher speed. I don't think any air-cooled GS can do lock to lock stop and throw the rider on the floor (unlike the LC's).

" ...40kg in my overloaded givi treker outback 62 litre top case at 120mph..."

I wouldn't try that if you paid me!

But yes, if a wobble seems to come on, gently off the throttle should solve it pretty much instantly - no rash movements/reactions!

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[Skudd]

Re: tyre pressure sensors - once they go they go, there isn't a fix other than replacing with new.

You can change the battery, done it on both front and back, takes about an hour. There are loads of youtube clips on it.

 

[fair1535]

JUST FOR INFORMATION.

I replaced one of my sensors on tc 1200gsa (2013) with tire pressure monitoring sensor replacement 8521797 replacement for original part from amazon. 2 for £26, working perfectly 14 months later.

 

[Deleted account 211025001]

..........................

But perhaps the reason you notice it more than most on these bikes is the way BWM build in manoeuvrability - these things change direction like hoodie bike thief riding a 125 on acid - and this is far more fun than worrying about needing 8 foot of road rather than the 4 foot you need with a..........................

Awwww, that's made my day that has

Sorry Flip, I appreciate this is the technical section (although that didn't used to stop you did it ) and hope you get is sorted, it certainly doesn't right to me

Andres

 

[BillyBoxer6]

Have I read this correctly?
Are we saying that the TPMS will cause a Severe Wobble just because the Batteries are flat?
How does that work?
I don't have them or even pretend to understand how this Electrickery works, so bear with me.....

 

[Slipperyeel]

Have I read this correctly?
Are we saying that the TPMS will cause a Severe Wobble just because the Batteries are flat?
How does that work?
I don't have them or even pretend to understand how this Electrickery works, so bear with me.....

Absolutely. If there's interference to the sensor signal then EMR waves are no longer polarised creating induction due to the metal rim rotating. It can interfere with air flow around the wheel. It's a common problem

Actually, I think the tpms was an additional issue

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[BillyBoxer6]

Absolutely. If there's interference to the sensor signal then EMR waves are no longer polarised creating induction due to the metal rim rotating. It can interfere with air flow around the wheel. It's a common problem

Actually, I think the tpms was an additional issue

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I know how Tech Savvy you are, so you had me going for a minute there Rodin.!!