Anyone got any advice? For our 4 (almost 5) year-old daughter. Will likely be used mostly on forest trails. What about gears – a waste of time or not? Thanks

don't wory about gears, they'll always be in the wrong one and it's just more weight for you to drag around.

folding ones make some sense if you're going in the car as they're pretty long.

if you have room fit a rear crud catcher on your bike and several fron crud catchers on the 'down tube' of the trailer bike – the kids pick up all the mud and water off your back wheel otherwise.