status: designing
sketch using cheap 3D cad program
After touring with Evan and his Kotzur
trailer I've been thinking about the replacement for MegaTrailer. MegaTrailer is
now donated to Bike Club because
it's a bit on the big and heavy side to store in my bedroom. So I want a
replacement that's smaller and easier to manage, and ideally lighter as well.
Evan's one has a neat feature - the drawbar slides out so you can move the
trailer back further behind the bike. That makes it possible to balance bigger
things on top of it (sheets of plywood, for example). It's make of CroMo so it's
fairly light, but like all Kotzur products it has a few quirks... and Evan has
bent the 12mm single side mount axles.
I've decided that bins beat timber for most things, it's so much easier to just throw stuff into the bin and not bother about arranging it and tying it in place. So if I make it the size of a Bunnings bin, and make the rim around the top higher than the wheels I can remove the bin and carry big flat things. Or just put them on top of the bin.
The extending drawbar seems really, really useful to me. As long as it doesn't twist under load. So I'm planning on that. But I think I'll stick with my chain-and-spring hitch, because I like those and it's easier to make the thing fit a standard bike (Evan's trailer requires a very specific mount on the bike, one that would be hard to retrofit).
Evan has 12mm solid axles on his trailer, but they're single sided mounts and he's bent them. Honestly, it's from abuse more than misdesign, but arguably Wayne should have expected Evan to abuse the thing... he's done that with everything else. So the 100kg load limit to Evan means "can be ridden down stairs with a bit over 100kg in it". Repeatedly. But anyway, since I know that I abuse these things, and that MegaTrailer could take at least 200kg (enough to push the wheel bearing through the races of cheap wheels). So I plan on getting a couple more 20mm through axle wheels from Ben, and using short lengths of 20mm rod to mount them on, backed by 22mm tube between them (900mm of 20mm bar is heavy). I'm still tossing up brakes, I'd kinda like them but it's a hassle to fit them. So I'll probably build the trailer with disk mounts then decide later.
So now it's just a matter of drawing it up, making some measurements, and
seeing what it looks like. I use Turbocad for this ($US99... proper CAD is
$2000+) even though it's painful to use and its 3D is a joke. But it kind can be
made to work, albeit slowly. Pics:
It will be about 800mm long, with the option of extending the drawbar so that the front edge is about 800mm behind the rear wheel of the bike that's towing. Or 900mm behind the towbar on the quad. So I could stack something about 3.5m long on the back of the quad without really struggling, or reasonably carry a 2.4m long sheet of plywood on the trailer.
Now all I need to do is buy a TIG welder, build a workbench and start on the trailer. Or the commuter that I'm also thinking about.