My 9 year old is 54.5" tall and is doing really well on his Specialized Riprock Comp 24. We are definitely hitting some rocky terrain, and I'm looking into getting him on to a full suspension bike with a dropper post. The ideal bike out there looks like the Whyte T130 SR for kids. Does anyone have their kid on one of these? I like the Fuel EX Jr, but don't love the 2x drive train, and the fact that it doesn't have a dropper post. Any real world feedback on these 2 bikes, or similarly spec'd bikes, would be greatly appreciated.