Your Trek 830 is made of chromoly steel. If properly cared for, it will continue to render excellent service to you for many future decades to come. I know, because I currently own three chromoly steel framed bikes. One of which is close to thirty years old, and it's my favorite riding bicycle. It's just as smooth, comfortable, and agile, as the first day that I bought it. I have made certain throughout the years that all of my bikes are kept dry. I also immediately cover any scratch with matching fingernail polish. Other than a slightly worn decal, my bike looks just as good today, as it did almost thirty years ago. Steel is amazingly durable!
Additionally, aluminum has its deficits in terms of a shorter fatigue life, and a comparatively low yield capacity. That means that everytime it's used, it gets closer to its fail date. Aluminum can only withstand a finite number of stress cycles. This fact does not apply to steel. Also, in the case of an accident, aluminum will tend to crack, snap, or break, as opposed to bend, due to its low yield capacity. That's why you can readily observe aluminum frames breaking up in the middle of a top or down top, instead of at the weld joints.
Chromoly steel is quite simply, much stronger and more durable than aluminum as a bicycle frame.
OTOH, if your going to be involved in road or mountain bike racing, then aluminum or carbon, just might make the difference. For the daily commute or long distance cycling, aluminum or carbon would not be my preferred frame materials. Of course, for me personally, I'd even race with an 853 chromoly steel framed bicycle.
Last edited by SlimRider; 05-05-12 at 12:46 PM.