I'm interested in knowing the capabilities of my Trek 7.1fx hybrid's frame. I commute full-time on it. It's an aluminum frame and I had heard that aluminum isn't that great. But then I realized that Trek's frame has a lifetime warranty. Does this mean that they don't expect it to break or does it just mean that they don't think I'll keep it til' it does? Basically is it a "When" or an "If" as to whether or not it would ever break under moderate use? And in what time-frame would it be expected to give out? Considering I take pretty good care of it.