I just turned 50 and am thinking about getting back into riding, after about 35 years. I used to ride an RM 80 back in the late 70's. Planning to do mainly trail riding. I'm not an aggressive rider, but I'd prefer something that will respond, if I do decide to romp on it. I'm 5'8' and around 140 lbs. One of my concerns is maintenance costs. I can do some of my own basic maintenance, but not major engine work. Does anyone have suggestions on what bikes to consider, for someone my size and age? Thanks.