Rode out from Chicago the last three years, not sure if I'm gonna make it this year as my schedule is pretty booked.
I always bring one M body and a 50 cron, and a saddlebag full of Tri-X. There are thousands of characters out there, but remember, it is a Harley rally. Most of the folks we met were middle aged, heavy set, midwesterners, who trailer their bikes out there behind a rented RV (would love to have that market). And most of the folks are really nice. But again, it is a Harley rally.
I'm pretty much shooting the entire time I'm in town and go through 10-15 rolls a day.
The few times where I had issues were with taking pics and some biker (usually drunk) who is trying to impress his mates starts to give you a hard time. As an example, one time I was doing a story on this airbursh artist who airbrushes peoples bodies outside one of the bars. He and I got along well and many of the folks he was airbrushing were fine with me taking pictures of him working on their bodies (no nudity). Anyway, some drunk biker with his drunk mates got his shorts in a bunch because his "old lady" was walking around with her "baps out" (as the Brits would say), and this biker thought I was going to get a picture of her, half naked, in one of my shots. (If you saw this woman you'd know why I would be very careful not to get her in any of my shots). Anyway, I'm a firm believer that you never back down from a bully, so I told his drunken self that I'd be sure not to get any pictures of his old lady. He wasn't satisfied, so he put his mates on me. Three against one, all three of these no-neck monsters were twice my size. Luckily the airbrush artist and his mates stepped in and told the drunk biker that, "If your old lady is going to walk around with her t*#s out, you better get used to people taking pictures." And he backed them down.
That kind of BS goes on at Sturgis all the time, so just be careful.
A suggestion, one day get to town as early in the morning as you can, it's beautiful watching Sturgis wake up during the weeks of the rally.
And have fun.