“We already have topeak bags and a child seat. This adaptor is a great idea as we have swapped racks on many previous bukes to allow us to use the topeak system accessories. Works well for us.”
“Got a rack already on your bike but wish you had a Topeak MTX rack with its fancy track to slide the bag on and off of?
Buy this and bolt it to the top of your existing rack, and now you do!
Four stars because it's a bit inflexible about where the mounting tabs can go, and is made from plastic, rather than the metal that the actual Topeak racks are made out of.”