My buddy showed up to a group ride with a TDF KOM jersey on. He got railed on pretty hard verbally (all in fun) but was really put to shame when we hit the climbs and he got dropped.

Now, just having a nice bike is not prob. Just don't be a cocky jerk like the others said. A person could have a beater bike and a big mouth and be as bad or worse. I bet you'll get into road so much you'll appreciate the nice equipment as opposed to having to spend time and money upgrading it or having to buy a new bike after 6 months.

Lastly, I bet you are pretty fit from mountain, yes? To be an official roadie, I think you have to go and shave your legs now, lol!*

*a week after I started road, I shaved--couldn't believe I'd ever do it.