-
I think the sweet spot is long top tube, long flipped stem, seat as far forwards as possible, with swept bars (eg One One Mollymawk) and Spirgrips or similar for them to hold.
Basically make them sit as far forward and as tukt as possible without them hitting their legs on the bars. While you are as upright and sitting as far back as possible.
Also keep their feet nowhere near the front wheel obvs.(Need to trim mudguard stays)
Any budget suggestions for handle bar setups for kids shotgun seats?