[QUOTE=JeanCoutu;5566307
So if you want to build a tongue so that it won't break, here's what you do: Visualise this part being very well built, at least twice as strong as it needs to be... Do you see it? Ok, now double it & add some metal bits to help resist twisting, and it's just about right. At this point, something else is likely to break first.[/QUOTE]
Yeah I run across that problem with my own homemade bike trailer I just recently built. Since the trailer tongue on my trailer is affixed to the seatpost, I used 3/4-in EMT conduit bent into a backwards "S" design (with the help of a tree) and bolted in three places to a solid piece of 3/4-in plywood under the trailer. The lead clamp is a small U-bolt drilled thru the 3/4-in plywood and bolted down. The clamps directly following the lead U-bolt are 3/4-in metal straps made for affixing 3/4-in conduit to walls and such. The metal straps are a bit flimsy IMO, so thats why I used a U-bolt as the lead clamp. The torsional and lateral stresses dont seem to effect it so far.
If I say so myself, I believe I did a fairly good job building this trailer. I have about $100 in it, including brand new 20-in BMX Mongoose wheels and tires I bought off ebay. The trailer pulls like a dream, with about 2 lbs draw weight on the hitch, and tracks true and straight. I was all set to post a big, nice thread on this project to help others in this forum, but my digital camera took a dump on me at the last minute. (a complete, and utter bummer)
Just as soon as I beg, borrow, or steal another camera I'll post a full spread on it.