Modern Vespa

For those of you who own the 300 and an earlier 200+ model, you might be able to measure the difference.

Getting a trail measurement looks difficult, as it's hard to establish the steering head line.

But, if (I'm guessing) Vespa did not change dimensions behind the steering head, the wheelbase should be a little longer with an increase in rake.

Or, if the fork remained the same (preserving the shock mount angle relative to the steering head angle), then a line drawn down the shock centerline to the ground (psuedo steering head angle) and measured back to the front wheel axle might reveal a trail difference.

I would not expect more than an inch in either case, probably less.

Looks like the 300 has a shorter wheelbase than the 200/250s, by 1 inch.

Seems unlikely everything else (e.g. geometry) stayed the same or --if so-- that a shorter wheelbase would purport to solve the wobble or improve stability.

Does seem more likely that a shorter wheelbase was balanced with more rake/trail.

mystery continues...

Very interesting, I didn't know that the wheelbases differed from the 250's and 200's. Where did you find that information? I'd like to find that information from a single source that actually did the measurements. So far I cannot locate it from a single source.

Never experienced a wobble with my 300. Ride was smooth from Day 1. Now have over 2100 miles on it.

http://www.vespausa.com/scooters.php#/spec/Vespa GTS 300 Super

Specs are on the vespa site. Same wheelbase for the 250 & 200, the 300 is shown as an inch shorter.

Thanks Jim, for some reason yesterday when I tried to get that info from Vespa USA, that page wasn't loading. Vespa Canada's website doesn't even list the 300 yet. I guess that partly explains the difference in feel of the handling, but I wouldn't have expected a shorter wheelbase to make the 300 feel more planted and handle better, there must still be some other factors like the suspension or springs.

With my GTS 250 Super, having the 300 body style pretty much, never had the wobble occur. Couldn't MAKE it happen. With or without a Faco mid size screen. Came with Pirellis. Had the shocks on softest, and second most softest...always just fine. I always carefully check for 26 psi in front tire and 29 in rear.

I agree and first thought it might be a misprint. Maybe it helps weight distribution by putting more weight on the front wheel? (thought in the past that --like a shopping cart with an un-weighted/wobbling caster wheel -- a rear weight biased Vespa might exhibit similar symptoms, but that doesn't track with the symptom occurring during decel when weight shifts forward...)

Does make me wonder how Vespa achieved a wheelbase reduction (maybe engine/drive assy moved forward)

On my next GT200 tire change, I'm thinking of a change in ride height that will increase rake/trail, which means smaller diameter in the back and/or taller diameter in the front.

I've also noticed that with a passenger (more squat, more rake/trail) the scoot seems more stable. This would support a reduction in rear spring preload. Might try that too.