I'm in a similar situation. I purchased my 12yr old son (who is now 14) a Motobecane Vent Noir that he is now a perfect fit for. I also have another son, who is now 12, who feels left out as he doesn't make the outings with brother and dad. My oldest is riding Pelotonia this year and has had multiple rides of 50 miles... so he's a capable rider. So my thought it to get my older son a new bike and have the Vent Noir go to my youngest. Since my oldest is a capable rider and expects to continue riding I don't mind getting him a nice bike. He is 5'6" and test rode a 54cm Fuji Roubaix with Ultegra groupset (yes, I know he doesn't need Ultegra but the bike is on sale for 799). The sales kid is continually chirping that the bike is too big for my son. My son was happy with the bike but did mention that the stretch to the bars may be a little much for a long ride. My thought is... well, get a shorter stem and move the seat forward?!?! I don't want to dismiss the sales kid (who should presumably have a reason for his opinion) but does anyone have an opinion on this? I mean my son is prolly going to grow a few inches by next year and if so, the bike will last him years. But I really don't want it to be a painful experience for him and I fear his excitement for the bike may be in part due to my commenting on it being a nice bike. Has anyone bought a bike for a growing teen?