Trailer picturesMarch 2003 - this trailer is SOLD.
This trailer was the first I've made, and it's served well. But my Mk11 is now the one I use most, largely because I never got round to making a hitch to tow this one behind my town bike...so to clear some space, it has to go.
It's a large utility trailer - bigger and with more capacity than most commercial ones. It's been proven to 100kg or so - but that's really the limit, as the tyres look pretty squashed by then. It will carry long thin loads up to almost 3m long when you move the cross-beam right back. It easily carries a couple of upright bikes. Pictures of it in use have appeared in various issues of Velo Vision or see the write-up here. See also my third trailer design.
It's made of square-section steel (about 1" square, probably 1/16" thick at a guess), and has aluminium angle pieces at the corners. Painted in Hammerite blue. The cross-beam between the two wheels is joined on by simple U-bolts, so can be fitted anywhere along the main rectangular frame (so you'd put it right at the end for long loads...) I usually had the cross-beam above the frame for extra stability, but you could have it below as well:
It's intended that you mount baskets, plastic boxes etc onto the frame to suit your needs. Bread-boxes (if you can get hold of some legitimately) are perfect. Dimensions are:
Weight - not sure, probably 10-12 kg at a guess.
Two 12" (ERTRO 203 not 305 as it says on the drawing, tyres easily available) wheelchair wheels with 1/2" one-sided axles are used. They even have little reflective bits inside the rims as a safety measure:
The draw-bar is bolted onto the frame using a few bits of machined aluminium as spacers. It's arranged so that the hitch falls just off-centre, so the trailer should run straight behind the bike. There's an extra hole half-way up the drawbar and on the chassis so that it can be used in a shorter, more compact position - but I just leave it as it is on the photos, normally. All of the bolts etc on the trailer are stainless steel by the way.
The hitch was originally designed to fit on my S-327 recumbent trike, with its large monotube rear swingarm. You'd have to fettle the hitch a bit to get it to fit a normal bike - maybe make some sort of adaptor plate. It's a bit dirty and corroded, but still works fine. The M4 stainless steel studding I'd used to attach it to the S-327 has corroded rather badly, and I couldn't get it out - so had to saw it to get it off. With a bench vise and a hammer, I'd imagine getting the bits out would be easy enough:
To operate the hitch, you lift the little lever - this 'opens' the hole. Then slide the shaft of the hitch up into the hole, move the lever 180 degrees so it's pointed down (so gravity helps prevent unwanted opening...) and the hitch is locked. Then click the split pin on the cord through the hole at the top of the trailer's hitch shaft - this is the first safety backup, and would prevent the shaft dropping out if the lever is accidentally raised. The second safety backup is the other cord, which you loop round a frame tube on the towing bike and attach back to the small karabiner on the trailer. This stops you losing the trailer even in the event of a complete hitch failure.
I must admit that the 'universal joint' on the trailer part of the hitch isn't the finest bit of engineering ever. It does work, but watch out for the bolt retaining the vertical shaft bit coming use - if you remove it, use threadlock when retightening.
The trailer packs down reasonably well if you just remove the cross-beam - it's then a thin, flat package. You could also remove the drawbar if you wanted to really pack it down. The wheels come off the axles moderately easily (or did last time I tried several years ago) once you've removed the retaining circlips.
Finally, here it is in action behind my S-327 towing an armchair...
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