Hi, I have quite a bit of experience at karting around bikes off a towbar, but one recommendation - do not get a cheap screw down metal top one from supercheap, autobahn etc... They are crap and not worth the time and money, for starters the fixed size of the metal top is useless with today's varied sized frame bikes, especially on kids bikes. Go for an 4 bike velcro strap and rubber protected bike rack. I've carted 2 adult and 2 kids bikes off the back of the towbar with a trailer as well with a bike on that. THe bikes don't move too much, but I tie mine together on the bits that may rub with strips of a old tshirt. Mine is a PACIFIC I.B.D made in tiawain and purchase from my local bike shop, did not go looking especially for a brand so it must be a common model. Good luck. Jolyon