I just got rid of my 2003 Burgman 650 after putting 38,000 miles on it. For the past year and a half, it shared my garage with my 2006 People 250. This area of the country is frequently windy. I found that the P250 was just as stable in crosswinds as the Burgman despite weighing a lot less. I do attribute that in part to its wheel size. But it is the combination of everything that matters. Wheel diameter, tire width, weight, wheelbase, frame geometry, suspension quality, center of gravity – it all affects stability and handling. So you can compensate for what would be a deficiency in one area by excelling in others. Suspension for instance, is clearly superior on the Burgman.
A couple of other factors bear mentioning.
The popularity of smaller wheels is driven by two things. Styling is one. You can’t put two 16″ wheels on a scooter and get that popular flying wedge look (aka Burgman, Majesty, Xciting). Neither can you get the traditionalist “Vespa” look. You inevitably end up with the “People” look, which isn’t as widely popular. Also, the shorter riders have issues with getting their feet to the ground on the “tall wheel” scoots – which limits their market audience.
Functionally, I’ve noticed that the P250 with it’s 16″ tall wheels and narrower tires works very well in gravel. I hated riding the Burgman on gravel. The wider tire smaller wheel format caused it to squirm around a lot – probably aggravated by it’s greater weight as well. The first time I had to do gravel on the P250 I was quite pleasantly surprised – and the wheel/tire width set up has a lot to do with that I suspect.
The Kymco Grand Vista, the late B&W 250, the Burgman 400 – have a lot going for them despite smaller wheels. I’ll readily acknowledge that. They are fine scooters. However, I’ll take the opportunity to point out that the Burgman 400 DID up it’s wheel diameter as part of the ’07 model revisions. 🙂 Couldn’t resist… 😉