So I'm looking to pick up a hybrid before the summer so that I can have a bike to use on semi-rough trails, commute to work, and ride around town. I'm trying to keep the price below $500 because, among other things, I plan on leaving it locked up outside fairly often and I live in the bike theft capital of the US (Chicago). Plus I already have a decent road bike - a Scattante R660 - for when I just want to go fast. My goal by the end of the summer is to be able to ride all the way up to Milwaukee (about 90 miles) and back in a weekend without too much trouble. I've tried taking my road bike on some of the trails around here but it just doesn't seem to like the rougher gravel and I'd rather not trash my good bike.
I test rode a Trek 7.1 FX today and was highly impressed with it, but I have some lingering concerns before I commit. There's obviously a big difference between riding around the block and riding 90 miles. Can any of the veterans please weigh in on their experience with an all aluminum bike on longer rides? Will the aluminum fork be kicking my butt after X miles? Or should I consider something else entirely? What are some of your experiences with the Trek 7.x FX line on longer rides? I'd love to hear what some of you have to say.
Also, I'm 5'7 with a 30" inseam. The frame on the bike I tested was 17.5" and seemed to fit perfectly. Does this seem pretty accurate? I saw another post on here where someone else had the exact same measurements as me and also did well with a 17.5" frame but I just wanted to make sure.