the bikes are not too big, just right or maybe just on the big size, but they're growing fast. they can get on/off the bike themselves with out problem...except when they use the wrong leg to boost themselves up, but they're learning. and on the downstroke, their knees are not locking, so the bike is a good fit and have a cpl years of use out of them. My son was riding just fine with me the other day while we were waiting for my daughter to get back from the ER....busted her teeth pretty good falling off a chair. so Im hoping its just a "break in" problem that they will have to accustomed too.