Dog trailers have tow bars or arms. You'd need to install the universal hitch right onto your bike's axle. For a bike with a quick-release axle, remove the skewer and insert this through the hitch opening. Push the skewer into the bike axle and secure it well. Push the latch securely. There is no need to worry about the hitch's positioning as it will correct by itself naturally. For bikes with bolted axles, you'd need to remove the axle bolt. Put the dog trailer bike's hitch onto it and secure the bolt. If your bike has an internal gear right within the wheel hub, then you would need a hitch adapter.