Originally Posted by
Leinster
I would say a 23" road bike for a 5'7" rider would be a bit on the big side. If you go with a 52 or 54cm (21 to 22") frame, it should be big enough now, and still offer some room for growth (I'm 5'10" and my 2 road bikes are a 54 and a 55cm)
If you don't know what type of cycling he's going to like in the long run, and he's happy with your hybrid, then continuing with a hybrid is probably ok for now for going on rides with you. Then he can think about specializing when he starts going on off road adventures in the wilderness, or long road rides to neighboring cities, or doing stunts off jumps, or whatever floats his boat.
Just checking back in - there was a great deal on a used Giant gravel bike at the local shop, $900 for ~4 years old with 105. He test road that, a hardtail, and a hybrid, all in his size. Turns out he liked the hybrid the best anyway, which saved me $400, though I feel bad for not taking advantage of the deal. I'd have bought it for myself, but alas, his size is clearly bigger than mine now. I couldn't stand over the damn thing.