My son will be 12 this week and wishes he could ride to school. Sadly his route is 5 miles and he'd need to cross the river, which only has main arteries crossing it. Not going to happen. That said, he's been riding in to work with me all summer, about a mile and a half, and though it was a bit of a struggle with the hills on the way home at first, he did eventually get there. And on a 20yr old 10-speed. If you can, I'd recommend riding at least to school, and maybe home also, a couple of times with him to get him into it. Stop for water or to walk up a hill, show him the right way to cross a driveway, etc.
Bike aside, make sure he has all of the safety equipment he needs. Front and rear blinkies, reflective stripe on his backpack, helmet, maybe even front and rear blinkies for that. Might not be a bad idea to get him a basket or something for the back to put his backpack in, w/ reflective stuff on that. Get him involved in picking out the bike -- my son and I are planning to "pimp" his bike out. Fresh paint, new tires, maybe a rack and baskets/bags, flame stickers, new handlebars... should be fun
