I can’t remember what brand we had (13 years ago), may have been Trail-a-bike. I used it with our son when he was between four and five years old (he was big for his age). He enjoyed getting out behind me on what he called the “stick” bike. However, while there were no problems on level ground, I found the version we had difficult to handle on uphills (Brandymore Castle on the W&OD and the link from n Four Mile Run Dr to Ohio St N. We got him his own bike when he was five and he immediately fell off and has pretty much refused to ride ever since. 