This big wheel is probably REALLY wonderful for a 4yr old. But we got it for my son that is a VERY tall (38") almost 3yr old and he couldnt reach the peddles properly. It was frustrating him, so we had to return it, and I purchased another kind thats meant specifically for smaller kids. It was MUCH more costly though, so this was the BEST value, had he been able to use it.
I bought this for my son who just turned two. His feet don't quite reach the pedals yet (even with the seat all the way up), but he loves to push it with his feet on the ground right now and will get there soon!