My 13 yr. old (5-3" 120 lbs) has discovered riding trails here in Vancouver; He is attending a summer camp with his department store bike. Since he has a birthday coming up, we'd like to do a father-son build up of a good starter bike together. I have a larger mtb with low wear XT components and would like suggestions on a modest frame/fork combination that will allow us to strip the parts off the old bike and install onto new frame & fork. Realize we'll have to check to make sure most of the components fit first. I have the skills but not much mtb knowledge.