The only time I ever privately sold a car, it was to a friend I'd known for several years, so I wasn't too concerned about fraud. I support the idea of meeting in person with the seller and watching them take money out of their bank (or a cashier's check) and then hand it straight to you. It's overkill, in some sense, but it does protect you from each other. You see that it's legit money. He sees that you've got a legit bike.

Now, if it were a car, you'd let him test drive it and you'd go along as a passenger. For a motorcycle, that doesn't work as well. The last thing you want to do is give a stranger the keys to your bike and let him zoom off without having paid you first...