I am part of Big Brothers group the kid I am with is not active, He had fun when we have done bike rides in the past. I have been trying to talk him into joining cross country team or basketball at school and he seems excited but never does anything about it. I was thinking about trying to get him to do a dualathon with me. I think if he does it with me he might be more willing to try. There is one in granite bay that is 2 run 7 bike 2 run and is free. Its in jan so i figure that is plenty of time to get him ready... Is that to much? he is 13... Next and more why i am here... he is currently using a way to small for him, beat to **** bmx bike.... I was hoping to pick up a cheap old road bike for him to use and train on. I am poor so I am looking for a very cheap used bike. I dont know what to look for, i was going to cruise craigslist but not sure where to start any help would be great. He is about 5 foot tall maybe alittle less so what size frame would he need?