Body Glide is used to prevent chafing. I've never used it for cycling, only for running. Even then, I usually don't need it unless I'm going 8-10 miles. At that distance, I start having a few spots where my sports bra can bother me. I'll also occasionally put it on my inner thighs to keep them from rubbing together too much while running.

I have the stuff that looks like deodorant. You just rub it over the spots that tend to chafe. For cycling, I don't have much problem with chafing. If I do, it's usually something with my shorts that's bothering me and I'll just use a chamois cream.