One thing I’ve noticed about other bmw riders is that they typically don’t keep their bikes super clean. Most have a patina of road grime on them, even. I think this has something to do with the image of bmw people being “real” riders, versus the image of harley riders being people who put their bikes on trailers and go to shows. Sort of a classic yin-yang thing going on here, I suppose. The whole psychology is a complicated thing, with a hierarchy of brands and odd pack mentalities. You can see all this downtown, where bikes park in clusters of these types, none daring to mix for fear of upsetting the hierarchy. Basically, you’ve got your New Harley Guys, Old Harley Guys, Japanese Cruiser Guys, Japanese Sport Bike Guys, Goldwing Guys, and Italian Sport Bike Guys. I can see whay the Harley guys stick together; they need to share parts and tools. Don’t know what motivates the others. Here is an interesting study (Subcultures of Consumption) discussing sme of the reasons people buy motorcycle brands.