Wobble and tryes

[Deleted account 181015003]

My bike since new F800GS 2014 has always has a wobble sort of oscillation on the handlebars on a closed throttle it has been back to the dealers a couple of times to fix the problem and to some degree a new front wheel improved it.

The problem seemed to happen when the bike was doing about 50 mph and if I closed the throttle I could feel a side to side wobble through the bars if I released by grip it could be clearly seen getting worse as the bike slowed down and would settle at about 25mph.

I always suspected the OEM Pirelli Scorpion tyres but there was no way to prove this without changing them and I was not going to replace 2 good tyres just to find out. After 4400 miles the Pirellis were past their best and I have a trip coming up in a few weeks I thought now is the time to try something else I bought a set of Anakee 3s from Tyreleader and fitted them last night this afternoon I tested then no more wobbles so if anyone has the same symptoms and Pirelli Scorpions tires the tyres will be more than likely the cause.

The Anakee 3s seem to ride really well and the bike tracks and corners great I was going very steady just to scrub them in and worryingly I am at the edge of the tyres all ready the profile does not look to allow very much lean angle and I am a bit worried I will run off the edge the front looks the worst when comparing it to the Pirelli that I removed

Is anyone using these tyres on a F800GS and has any issues riding off the edge of the tyres I am no cornering god so dont expect to be on the edge just running them in ?

 

[Gigsy]

Been running them on my F700 for about 5k miles and they haven't let go yet.

 

[slparry]

My bike since new F800GS 2014 has always has a wobble sort of oscillation on the handlebars on a closed throttle it has been back to the dealers a couple of times to fix the problem and to some degree a new front wheel improved it.

The problem seemed to happen when the bike was doing about 50 mph and if I closed the throttle I could feel a side to side wobble through the bars if I released by grip it could be clearly seen getting worse as the bike slowed down and would settle at about 25mph.

I always suspected the OEM Pirelli Scorpion tyres but there was no way to prove this without changing them and I was not going to replace 2 good tyres just to find out. After 4400 miles the Pirellis were past their best and I have a trip coming up in a few weeks I thought now is the time to try something else I bought a set of Anakee 3s from Tyreleader and fitted them last night this afternoon I tested then no more wobbles so if anyone has the same symptoms and Pirelli Scorpions tires the tyres will be more than likely the cause.

The Anakee 3s seem to ride really well and the bike tracks and corners great I was going very steady just to scrub them in and worryingly I am at the edge of the tyres all ready the profile does not look to allow very much lean angle and I am a bit worried I will run off the edge the front looks the worst when comparing it to the Pirelli that I removed

Is anyone using these tyres on a F800GS and has any issues riding off the edge of the tyres I am no cornering god so dont expect to be on the edge just running them in ?

http://www.eurospares.com/graphics/chassis/RoeSAEPaper.pdf

 

[Bem]

Not too sure what a Tsypkin Locus is, much less how to spell it.
However I can say for certain that only having two wheels means that the riders assumption as to what is happening and where are very often misplaced. Uneven wear (comparing front to back, profiles or tread depth) can result in the Tail Wagging The Dog ie the blocks or tread pattern in the rear producing an effect felt at the front through the handlebars.
Just in the process of moving off Conti Attack 2 (great when new) onto Pilot R4 - only the front fitted so shimmy still in progress. I expect it to go away next week when I fit the rear (or else start looking seriously at a full overhaul of Everything).

 

[DaveC]

That's an interesting document, but waaay to technical for me.

However my understanding from it suggest that, all things being equal, it's the tyre stiffness and/or the loading on the tyre that causes the weave/wobble (for particular forks and fork settings).

My guess would be that lowering tyre pressure would make a difference firstly because it alters the stiffness and secondly a bit of tyre damping would be introduced. Also loading the bike differently (more/less weight on the front) would change the oscillations. With it being an oscillation I would imagine harmonics get involved so small changes could make all the difference and it is likely counter-intuative changes (ie increasing tyre pressure) may work too.

Scorpion Trail tyres have been around for years so there's nothing inherantly wrong with them. I've used them for years myself (not on a GS though). It's interesting that a combination of tyre/bike/loading can make a measurable fundamental difference.

 

[JohnnyBoxer]

Head bearings shagged

 

[Deleted account 181015003]

Head bearings shagged

Brand new bike wobbled from day one so not head bearings the dealer checked the bike over and all they could find was the front was was a tiny bit egg shaped so they changed it buy put the original tyre back on I suspected the tires.

I put up with the wobble until it had done 4400 miles then changed the tires to Anakee 3s and it now fine

 

[Deleted account 181015003]

That's an interesting document, but waaay to technical for me.

However my understanding from it suggest that, all things being equal, it's the tyre stiffness and/or the loading on the tyre that causes the weave/wobble (for particular forks and fork settings).

My guess would be that lowering tyre pressure would make a difference firstly because it alters the stiffness and secondly a bit of tyre damping would be introduced. Also loading the bike differently (more/less weight on the front) would change the oscillations. With it being an oscillation I would imagine harmonics get involved so small changes could make all the difference and it is likely counter-intuative changes (ie increasing tyre pressure) may work too.

Scorpion Trail tyres have been around for years so there's nothing inherantly wrong with them. I've used them for years myself (not on a GS though). It's interesting that a combination of tyre/bike/loading can make a measurable fundamental difference.

I tried tyre pressures loading etc it did it one up and two up messing about improved it a bit but it was always there on the over run change of tires fixed it it could just be soft tire walls who knows

Some people have had similar problems on the R1200GS and some Triumphs with the first generation Trail Attack tires some combinations just dont work if this helps someone else get to the bottom of the problem that will do for me.

 

[DaveC]

I suppose with unlimited access to tyres and loads of free time we could find out what the real cause of your wobble was. I can't see that happening. Glad you found a solution tho

The question for me is; if you get a new set of tyres and you find they induce a wobble from day one, what can you do? Take them back and ask for something different? Can't see tyre fitters warming to that. So that's a couple of hunderd quid on tyres that are going to be a pain for hundreds of miles and maybe years of riding.

If you get a make of tyre that works, it may be best to stick with them. Some time ago I was considering changing from Scorpion Trails to something else, but the wise old tyre fitter ( ) said if it works for you why change? So I didn't. Would others be better or worse? I'll never know.

 

[Deleted account 181015003]

It could just have been a bad tyre or the tyre did not suit the bike both myself and the dealer tried everything but changing the tires it was a new bike and as you say you cant just throw away a new set of tires the change to the Anakee 3s and its completely gone and the bike feels so much more planted so I am well happy now if anyone wants a pair of Scorpions about 3/4 worn let me know they wont be going back on

 

[Bem]

See#4 above
Rear PR4 now fitted - wobble gone away.

 

[JJH]

Just in answer to the first post if your taking your hands off the bars at 25mph or less you are tempting faith. The property's of stability change at these lower speeds and disaster isn't too far away. Yes I know people ride at 1 mph sitting backwards on the back wheel. I tried all that. Still have the scars. JJH