How well does Aikido work against larger opponents?

Considering that Aikido is about throws, locks, holds, and the like, how well would it work against an opponent fairly larger than oneself? I would think that it would be much harder to throw somebody who weighs alot more than you... I'm thinking about learning Aikido, and that's why I ask. At my school, there's a great chance of some brute wanting to start a fight and attacking you. I'm skilled in other martial arts, but again, I'm thinking about taking up Aikido, so as much information regarding what I asked that you can give me would be great.