Trail-a-bike backrest
 

I see that Adams offers a backrest with straps for their trail-a-bikes that allows you to strap in a kid who is too young to stay on by himself. Has anyone here used this? It looks kind of flimsy in the pictures and I wonder how well it works.

I have seen it, but quite frankly, both daughters never used it. My eldest got on the trailercycle at 4 and my youngest at 3.5 (she tricked her daughter out of her saddle so she could use the bike). At their beginning, they could hardly reach the pedals, yet they had no problem holding the handlebars and staying there.

In fact, I think the backrest might fool the kid in thinking that he/she doesn't need to hold the bars that well.

It has worked well for my two year old. It is actually not flimsy, it's made of steel tubing, and clamps around the seatpost. It is also height adjustable (take the pad off, and there are two sets of pre-drilled holes on the plastic backer for two height positions)

I have it currently mounted on a tandem I made so we could ride together.

Also, for what it's worth, the straps can be tightened or loosened. I started with them snug around my son, and now run them tight enough to save him from a bad fall, but loose enough that he needs to conciously hold the handlebars.