I have a kid's trailer bike - or is the right term a 'tag-along'?. You know: a bike's rear-half, with wheel, seat, pedals, chain and a fixed handle-bar to hold on to. We got it from friends and I've used it once. The hitch is... well, it is the 'hitch' - the attachment that secures the tag-along to my bike's seatpost. It is too wide for my seatpost, I suspect because it was meant to come with some sort of plastic packing that got lost along the way.
I tried to pack it with bits of my old rubber inner tubes, and it seemed to work... but alas, only when going in a straight line. Any bends would cause the hitch to shift to the side, and because of the way it articulates with the tag-along, the more the hitch was out of aligment with my bike, the more the tag-along tilted. This happened, luckily, away from traffic one day I took my kids to Tatton Park (yes, I
drove there - spare me the sermon).
My eldest gave me a shout at some point, for I had no idea there was any problem. My poor youngest was holding on precariously, the tag-along tilted at an angle behind me. Another bend and she'd ended up on the ground. Not something a 4-year old is likely to forget (or forgive) in a hurry.
Last summer we gave family cycling a miss - it was, if you'll remember, such a washout, and what with the two weeks in Spain (rented car for 1 week) etc. So, yesterday I naively went round a couple of shops with the 'hitch' in my hand, looking for alternatives to fit my bike. It is not, I fear, as simple as that. "Make and model of the tag-along?" No idea - it's a rusty old thing we got from friends. "Ah, well, there are different attachments depending on the manufacturer". And as for a new tag-along, they are, in my view, too expensive for what they are - half-bikes which won't carry heavy loads and for not very long.
The answer is probably to grasp the nettle and teach the little one to ride - off with the stabilisers!