Hello! I am looking to upgrade from my 1999 GT Agressor to a 2008 Cannondale. I am a little leary of the advice from my LBS ( I think they want me to buy the more expensive model ) and would like some of your opinions since you all are not gonna be selling me a bike and can give genuine honest opinions! Anyway, I am 5'6" and about 145 lbs. I think the small frame Cannondale fit me the best. I am trying to decide between the F3, F4 or F5. My main uses will be some dirt trail riding and the rest on sidewalks, in parking lots, and city riding. I like to jump off of sidewalks and curbs sometimes and was also wandering about the durability of these bikes that I have narrowed it down to. I believe that by upgrading to even the F5 would be a big improvement, but was wandering if going all the way up to an F3 is overkill for my needs/wants? I am hoping that I will get more and more into biking if I enjoy riding the Cannondale a lot more than the GT since I dont think it fits me too well. The F3 is $1200 and it will sting quite a bit if that is the one I purchase, but am willing to do that if it is a much better bike over the two others. If I am getting very minimal gains, then I would feel more comfortable with the cheaper options. Anyway, thanks you in advance for some help! -- Tim