Modern Vespa

Surprisingly I don't seem to be able to elicit any wobble from my 300 Super. I was expecting to find it just as I had with my GTS 250 and the GT 200, however, I tried to find it on my way to work and alas there was none. Now I'm not complaining that I cannot find it, I'm just surprised. I have a Vespa flyscreen and a Givi topcase, the same items that I had on my GTS 250 as well as the heavy bar end weights. Has this been the case for others out there with the 300? I have been told that the suspension has changed, could this be the reason, or is it that the new standard tires suppress the wobble?

I'm interested to hear other people's experiences.

No wobble on my Super yet either, but I'm waiting to see what new tires (and accumulated abuse) do for that situation.

(I've actually tried hard to get it to wobble, up to an including decelerating with no hands on the bars).

I tried taking both hands off the grips this morning too while riding between the streetcar tracks as that texture of the road always elicits wobble. On the Super, it did not. Good to know it's not only me imagining it.

I really believe it is the Pirellis. My 250 did it, my 300 did not. The 125s and 250s now have Pirellis over here. Any more answers? As far as I am aware there has been no change in the geometry.

My old GTS had Pirellis but different ones, they were the SL model and not the GTS that I have on my Super. I know that the tire makes a huge impact on the presence or absence of the wobble.

I am taking about the GT23 on the front and the GT24 on the rear. I take it these are the ones on Benny's and Jess's GTS300s?

that make it wobble or dont make it wobble

The belief is that Pirellis (that variety of Pirellis, anyway) prevent the wobble.

No wobble. Thing is as steady as a rock.

Mine say GTS 23 on the front and GTS 24 on the back. I guess they chose this tire to prevent the wobble. Have you guys found the wet traction of these tires to be good?

The tires don't come balanced 100% perfect from the factory. Have your front tire re-balanced from a reputable shop if you have the wobble and I guarantee it will go away. I had that problem on a couple of sport bikes in the past.

My last set were balanced and yet there was the wobble. My current bike doesn't have the wobble.

We've been talking about the wobble here for a long, long time. While wheel balance can play a part in getting the bike not to wobble, it is far from the only factor. Balancing wheels is definitely a good idea, but it is definitely not a guaranteed solution.

I guess I lucked out or something. Never experienced any wobble not directly related to road conditions on my GTV. Doesn't matter if I have the tiny or the mid-sized screen, and I'm still on both my stock Savas.

Yeah, I don't have a 300 Super, but I thought this thread was interesting.

I read a lot about the wobble in forums here, and I have taken my GTS out for over 400 miles of rides now, on freeway and off, and haven't felt anything but wind gusts.

They're the ones. Fantastic grip wet and dry once scrubbed in. Not great wear, but that's the price to pay for stickiness.

That's good to hear Doug, thanks for the feedback on those Pirellis. I hope to have the same impression of these tires over time with them.

The wobble on my GT went away when I replaced the original Pirellis with Michelins.

There's a reason for that: the Savas were chosen for the GTS specifically because they do not induce wobble. Or maybe they just mask it. Either way, you probably won't feel the effect with Savas.

Also keep in mind that in most cases you won't feel the wobble unless you're decelerating through about 30mph with only one hand on the bars.

I think a lot of people never use hand signals and thus never notice the wobble. Those of us doing group rides using hand signals or who like to hand signal even when riding on our own, will notice the wobble when we take our left hand off the grip to signal. When I had original Savas on my GTS 250, I didn't have the wobble. My GT 200 has always had the wobble with its OEM Pirellis.

I have Pirellis on mine and it has a nasty wobble between 25 and 40mph.

My first Sava Front was defective ( wouldn't hold air) the dealer replaced it.
while is was low it exagerated the wobble.
I rode 3,300 miles after that and the wobble was only occasional and related to a heavy load on the rear and My sitting more forward on the scoot. and only while decellerating through the 30-ish range.
My Sear Sava blistered and bulged so I have since replaced both with the Pirellis 130 rear and 120 front. The Pirellis seem to have a wider tread area.
and the handling is now very nice. although I had no real complaints about the Savas, It was simply time to change.
The wobble seemed to go away completely but I recently found it simply by letting go of both grips while slowing down through 30. woo whooo.
Look MA no hands!, Look Ma no teeth!
All of the Pros of this scooter FAR OUTWEIGH the "wobble". 'nuff said.

some have it some don't, maybe the extra weight of the 300 or perhaps they have done something to the front or beefed up the swing arm we'll wait and see. I am not sure it originates from the front as on my GT that has the wobble it left for awhile when I changed the rear tire which baffled me the other GT can't be made to wobble no matter what you do to it.

this wobble is a classic front end phenomena on some motorcycles and even bicycles, and while most of a bike's pieces and parts play a role in the overall stability of the bike, the front end pieces are primarily involved.

I do not know the other bikes in question but my GTS 300 doesn't do it.
I don't have a topcase or fatty barends, but I do have a small windscreen, and I should, but will not, remove my windscreen to do a comparison. I'm not that curious. I'm just happy that I don't have the wobble.

However, I am interested in other's observations, with/without windscreens. A windscreen should apply significant force to the front end, both downward are rearward, and could easily be involved in stabilizing the front end. Also, it is not hard to see where different tires would affect this phenomena as well. I am also curious to hear about wobble experiences from anyone has moved their front tire up a size, like on the GTS this would be from a 120 to a 130 tire.

Don't bother. It's definitely not the windscreen.

(This problem has been discussed to death. For background as it pertains specifically to these bikes, check out: FAQ: Is it normal for a GT/GTS to "wobble"?)

I don't follow your comment. There is nothing about windscreens in the FAQ. I was not saying it is a cause, but rather a factor affecting stability. Many things affecting the front end are factors, according to the FAQ. The windscreen certainly has an affect--for example, the supports attach on either side of the bars, and exert a large force on each at speed. There is also a downward pressure on the headset, onto the steering column and tires.

More to the point, the FAQ doesn't really talk about the actual cause, which is a transient instability due to the front end being unable to cope with forces generated by the front tire and steering geometry.

I wrote the faq.

As I said, we've been talking about this issue for a number of years now. We've seen a lot of proposed solutions, some of which actually work for some people and many of which simply have no discernible effect. For the vast majority of people, it simply boils down to tires + factory steering geometry. The windscreen has never been shown to have any appreciable effect on the problem, and I say that with first-hand experience on four different GTSs with a number of different windscreens. Sure, in theory it could have an effect. In practice, the tires have the most pronounced and most wide-spread influence on the problem.

Has anybody established a relationship between rear shock setting and wobble?

I did get a wobble the other day

I have no idea if it was the same wobble, but a wobble it was.

I was adjusting my visor with my left hand, and braked for a red light using just my right hand on the front brake (it was late [or rather, early], deserted and I was feeling lazy. I also just wanted to break with one hand).

Anyway, as I did this, the GTS started wobbling or 'bucking' back and forth - is this the said wobble people have been throwing a wobbler about?

It's only ever happened that once, and it was rather violent and rather frightening

It's been theorized many times that changing the rear shock preload should change the angle of the fork. I believe a few people have found relief from the wobble using this technique, but (puts finger in air) I don't think it solves it for everyone.

Being cheap and relatively easy, though, It's definitely worth trying on your bike if you feel the wobble happening.

That sums it up. Even with the correct tires (what ever the may be) you still will probably have wobble.

From Cycle World:

http://www.cycleworld.com/article.asp?section_id=3&article_id=804

excerpted...
"The GT 200 upgraded the Vespa to a new standard appropriate for the third millennium. The next big update, the GTS 250, added extra spice to the concept. It was quicker, faster and featured a revised front-end geometry that improved steering response, while retaining the traditional trailing-link layout. A totally revised, leading-link front suspension would have enhanced the virtues of the chassis in terms of front-end response, stability and all-around riding quality, but that would have eliminated a traditional Vespa design hallmark. The following version, the GTS 250ie, was so brilliant that it seemed to represent the final evolution of the Vespa concept. It retained the traditional front-end design, but sported reduced rake that enhanced the precision of the steering response, and the engine's performance was terrific."

This article on the 300 doesn't cite specific geometry changes, only an improvement in chassis rigidity. It does cite geometry changes in earlier models that seem to contradict a perceived need for more geometry-related stability (i.e. reduced rake does improve steering response, but tends to impair stability).

Increasing rear spring preload would decrease trail, also impairing stability

But, such stability impairment usually surfaces as a "falling in" feeling upon corner entry on conventional forks. I have never seen wobble arise from aggressive geometry on my bikes.

My Vespa continues to mystify me, but I believe other unique characteristics (rear weight bias and trailing link caster effect) are contributing factors. Maybe, this combination makes Vespas very sensitive to tire condition, tire wear and passenger loading?

Finally, I may be mistaken, but the first pictures of a 300 I saw lead me to believe Vespa had increased rake and trail.

I'm not aware of any changes like that between the 250 and 300. That doesn't mean they're not there, but I don't think we've heard anything about it yet, and nobody has (yet) disassembled and measured the parts.

Thanks for the clarification. That is what I am talkin' about!! That it has been considered and disregarded is what I was wanting to know. I am surprised, but, you learn something everyday.

I still want to know if folks who have had a wobble condition and then had gone to 130/140 tires found that it had an effect. In theory, it should have an effect, but I don't know if it would be + or -. Any thoughts?

I've gone from a 130 in the rear to a 140, with no effect. Still wobbles. I can't speak for everyone, but I haven't heard any reports of that curing it.

It almost always first appears when someone goes from the stock Savas (on the GTS 250) to almost anything else. It'll be interesting to see what happens when people start wearing out the stock Pirellis on their 300s.

After trying various air pressures and suspension settings with a set of OEM Sava tires, and then a set of ContiTwists I ordered from Europe, both with and without trunk, I could not cure the "wobble" phenomenon many have written about. I even bought a precision tire balancer and rebalanced both tires to no avail.

I ordered the GT23 ($39) and GT24 ($43) Pirelli tires and IT'S PERFECT!!!!! Various air pressures, various loads, with and without trunk, trunk loaded to the max, or empty, NO WOBBLE!!!!! I love it! The tires feel great and are very responsive, great ride comfort, and are far superior to the OEM SAVAs. In this case, the only variable was the set of tires.

Also, the dealer's multi-thousand dollar wheel balancer did a poor balancing job. After dealer re-balanced to try to cure the wobble, my precision balancer found the balance to be off by more than an ounce!

I hope this info helps others fighting the wobble.

UPDATE: Over 1,500 miles now on Pirellis, and still no wobble, under any loading conditions!

Thanks Orbis, that is in keeping with what 300 owners have discovered with their Pirelli GTS 23 and 24 tires.

Has anybody tried these?
http://www.innovativebalancing.com/motorcycle.htm
Some people in the motorcycle community swear by them.

I would bet real money there's a geometry change between the GTS and the 300.

The minute I jumped on a 300 I noticed the steering was much heavier (not as quick to turn at speed) and the bike more stable. It was dramatic to me.

I don't think it's tires (although tire diameters can vary widely between brands for the same "size" of tire, and if the rear of brand A is much bigger than the rear of brand B it will effectively decrease the rake angle) but I don't think tire sizes alone could account for such a difference in handling.

Michael, I felt that something had changed too but wasn't sure of exactly what. The handling feels more secure to me. As well, for some reason I can do slow speed maneouvres more easily. I have more confidence in high speed turns as well.