I've borrowed a child bike follow me from a friend, thus a one-wheel bike that's attached to below the saddle. However, the tube is too small / attachment too big, so it does not fit.
I've tried to fill it up with some random fabric, but that's not stiff, so it moves left and right while riding. I think I need some sticky rubber (1mm/2mm) or silicone and put that in between. I have no idea where to find this, did some Googling, nothing showed up.
Does this make sense? Any ideas?