This frame is very nice quality, integrated headset, reverse dropouts and came with the tensioners. I didn't know the seat tube was 25.4mm as the typical junior frame is 22mm but GT makes a really nice unified seat and post that works well with this bike, It needs a 28.6mm seat clamp also. This bike fits my son well with 4.5" bars and 160mm cranks. Looks pro also. Great price for a very nice frame.