I've posted some of this over at the the "post your trailer" thread, But since the hitch/joint assembly seems to be one of the trickiest parts of any trailer project I thought I'd post this over here with more details of the hitch. What I have here is a simple hitch that has been performing pretty well for the trailer I've been developing. It's made with 1" x 1/8" mild steel strap, scrap wood and plastic and some nuts and bolts. There's on 8" length that's bent at a 20 degree angle to clamp it to both parts of the bike frame. There's a piece of hardwood with a notch cut into it to orient the clamp to the bottom part of the bike frame. It's also soft enough that it won't mare the surface of the bike frame. There's another piece of strap that's 6" long with a bolt welded to it's center (you don't need to weld it I just happen to have a welder handy) It's got some scrap plastic on it to protect the finish of the bike frame. At the far end of the first piece is a 1/4" hole. With that hole it bolts to a 3" length of twisted strap and that in turn bolts to the frame of the trailer which at that point is a flatten piece of 3/4" conduit. The bolt joint at the hitch allows side to side movement. The bolt joint joint at trailer end allows up and down movement. In normal use I've had no problems with it. It is vulnerable to twist. I'll be solving that by replacing the twisted piece of strap with two pieces of angle iron bolted together. I've also attached a picture of the trailer for reference.