Mine are on a 20" Specialized Hotrock and a Cube 200. Cube has no suspension fork, but is lighter, also has an ultra-low gear. The Hotrock's toptube is quite long compared to other 20" bikes (you know you're a bike nerd when you start comparing kids' bike geos). Surprisingly enough, the suspension fork seem s to help a little. I put DH stems on both bikes to make the riding position more upright.
By the way, anybody know if there are any decent tires in 20"? Most seem to have almost no profile and weigh almost as much as 650B XC tires. And decent 20" suspension forks and maybe even wheelsets (disc-ready)?
I like the fact that the Kona has disc brakes, but like most kids' bikes, it's dead ugly (and looks are even more important to most kids than they are to us - daddy, I want a pink bike…).
20" - maxxis big daddy. Great tires! Fork… i looked around and you're looking at $750 Suntour… more than the bike!
Kona's aren't ugly?! My son's got the Orange One and the daughter when light blue. Seems to be pretty HIP (although both have covered them in stickers)