I am an extreme case but I ride a Harley because it fits my 6'6" 400 pound body better than pretty much any other bike, my size is also why I wear almost no protective gear due to not being able to get stuff that fits without having it custom made. I have 2 helmets, a Simpson half helmet and a full face that almost fits right, I have yet to find another full face that comes close to fitting and it is even difficult to look since there seems to be no standard for helmet sizes.
And on the same note, where do motorcycle gear makers come up with their sizing, which does not match clothing sizes at all. Case in point, I own many coats and jackets in 4X and all fit fine, including my leather ones, ordered a first gear riding jacket in 4X, the front would not come within 6 inches of closing and was very tight across the shoulders. I would really like to have a mesh riding jacket but have been unable so far to get one that fits.
Yes, I am well aware that I am fat
1996 Harley Tour Glide
1998 Honda Helix
1989 Honda Pacific Coast
2000 westward Go-4
1982 Bluebird wanderlodge