Joined: Jul 2002
Posts: 40,863
Likes: 3,116
From: Sacramento, California, USA
Bikes: Specialized Tarmac, Canyon Exceed, Specialized Transition, Ellsworth Roots, Ridley Excalibur
I would buy a 54cm complete bike with decent components, say 105 level. Make sure it takes a standard seatpost, standard BB, no weird cabling. Adjust seat post and stem length as necessary until he is way too big. Then buy a bigger frame and transfer the components over.