I'm looking to buy a bike for my wife preferably used as I'm not sure she'll ever ride it. My thoughts are to go w/ a 4 stroke for the ease of ride but not quite sure after that. She is about 5'8" tall and weights about 140lbs. Would not be ridden on a MX track but only on trails and dirt w/ friends. If possible would not mind a bike that could do double duty if other friends came along. Thanks