Originally Posted by
astronomerroyal
Yes, yes, you should put this in one/both of the sticky threads. I almost missed this thread because I usually just visit the stickies.
Ok, I'll copy & paste the original post into those stickies.
It's a very nice trailer - beautifully proportioned.
I'm going to be the Devil's advocate and ask why you think it's more difficult to build than a two wheeled trailer. I've only built two-wheeled trailers, but it seems the Universally agreed upon difficulty is the hitch - the design of which for one-wheeled trailers (like yours, and BOB's ...) is essentially perfected.
This is my 4th attempt at a single wheel trailer design. The first 3 were successful failures
(successful because of what I learnt from them). In each case it was the hitch design that brought me unstuck.
In design, the difficulty is in dealing with the way loads are transmitted through the hitch mechanism without making it too heavy or losing rigidity. For example, if the trailer has a load and the C.G. of the trailer + load doesn't fall on a line between the hitching point and the trailer tire contact patch then a torque force between the trailer and the bike is generated during cornering. Any torsional flex in the chassis or worse, the hitch, can cause you all sorts of weird handling. If the load is big enough and/or the speed high enough, it can easily become dangerous. Then there's the fact that you have two degrees of freedom, but each DOF is separated along the hitch, and each one needs to pivot freely while remaining rigid in the other axes.
The difficulty in construction is in getting everything lined up without dedicated jigs. The symmetry of the hitch system is important in this design.
However the currently popular side-arm design for two-wheeled trailers is less than perfect (in my cringingly humble opinion) - which is why it might seem easier. I think the perfect hitch for a two-wheeled trailer may actually be more difficult to make, and is so few people attempt it.
I would respectfully disagree there. I sorted out a successful two wheel hitch design on my first attempt, and IMHO it's superior to most commercially available designs.
I'm interested to know why you think the side arm design is 'less than perfect'? (not calling you out, I genuinely want your thoughts).
Personally I think the side arm to the rear axle is actually pretty good even though it doesn't look as sexy. Purely from a mechanical design viewpoint it's actually a 'better' design than the single wheel trailer hitch. For example, it places lateral loads much closer to the bike's C.G. so any forces on the bike happen at the end of shorter moment arms and therefore have less effect on the bike's handling. Also, the two wheel design doesn't put any significant proportion of the cargo load on the bike (i.e. the hitch), although that's a property of the overall trailer layout, not just the hitch.
Certainly the trailer bed has to be more rigid in your case. I'm guessing the trailer weighs about 30lbs.
It came in at 22lb
...in aluminum I'm sure I could knock another 5lb off it.
Could you possibly expand (maybe just bullet points)?
If I make another trailer it may well be one-wheeled, so I'd like to know what I'm getting into.
Many thanks,
AR
Go for it! I love seeing the amazing stuff that pops up in this forum.
If you want more details on any of the specifics of my design just ask, I'm happy to share.