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Tuesday, April 1, 2008

Bike Trailer for Cargo

I've been working on a number of things, but the only thing worth posting at this time is a nearly-finished cargo trailer I can use on my bikes. I had to wait until I got a welder; now I've got a really cheap flux-core wirefeed welder. It works, but I'm still relearning how to weld at all, after more than 20 years of any amount of practice, and that was with a stick welder.

I figured after a couple weeks I had enough practice to make useful and reasonably safe welds, so I needed a practical project to test the theory, and picked the cargo trailer as one that can be road tested with lots of strain on it if needed, but safe since it's only cargo and not me depending on the welds yet.

I gathered up some pieces of an old computer desk, a couple of 24" Huffy bikes that had seen way better days, some washing machine internal braces, and an old lawnchair/pool recliner that had long since ceased being a chair. Unfortunately, like an idiot, I didn't take pics of everything as I took it apart and started modifying; didnt' occur to me to do so until I was nearly done. :( I'll have more pics attached to this post of various parts that look *similar* to what I used in it, as soon as I can get them in daylight. As you'll see in a moment, my nighttime camera skills leave a lot to be desired.

The first pic shows the trailer attached to my test bike (the Kensington):

The trailer is not very long, it's only about 34" wide from bolthead to bolthead on the outside of the rear wheels. I wanted to be able to get it thru doors wherever possible, but I ended up having to make it a bit wider just because of the parts I had, and not wanting to cut them if I could avoid it (for strength, and to keep from doing more work than necessary).

This is a better-lit shot of the other side and a bit above it, showing it's almost wheelchair-esque layout. It's been tested as a chariot riding around the yard, too, with one of my sisters standing in it, and it survived that ok. :-)

The black parts are computer-desk pieces, while the white ones are lawnchair. The blue and purple were the Huffy bikes. I only used the rear triangle part of the frames, from the seatpost/bottom bracket back. I did use a section of the front of one of the less-damaged Huffy's as my "hitch", along with a neck/stem from another wrecked bike that had a nice bolt-on facing to it, enabling me to easily put it onto my computer-desk pipe frame under the kitty-litter-pail cargo pod (moved to the Kensington test bike from the Columbia road bike in favor of my old baskets, until I get the vacuum-cleaner-bag-section cargo pods mounted on the Columbia, which should be soon).

This is a rear-view of the trailer, unfortunately you can see just how hard it is to see it; I only had one reflector I could bolt right onto it (the others in the pic are on the bike); I have to add another red on the right side, plus some amber ones in front, just to make a bit better visibility until I get the LED's for all my marker lights and turn signals for all the bikes. It also needs the fluorescent paintjob, as does the test bike, but I haven't had the money to buy enough paint yet (I got some, but it had to go to repaint the Columbia and my safety gear after nearly being run over, and picking a gravelly crash to being crushed under the vehicle that deliberately tried to run me down Easter morning just at dawn).

Not much to see in this pic, really, except the general layout and shape. There will be a wire front and sides, like baskets, so I can tie things down and keep them from sliding out, but not give me too much wind resistance (because it is tall, about waist-high). I decided on tall instead of long because I also intend to be able to have my disabled sister ride chariot style in it; she can stand or sit in it for trips to the store, restaurants, etc, since she can't ride a bike herself anymore. Taxis are too expensive for us to take to be able to go places together, but this will let us still do that. My other sister living here will be riding her own bike as soon as I get it put together from the other scrap ones I have. Might have to modify it to fit her, since most are too small or too tall for her. But that's for another post, sometime later.

This is a good side-shot of the "hitch", which works like a U-joint, in that the stem piece is clamped loosely around the rear bar of my cargo rack tubing, just tight enough not to wiggle but loose enough to rotate vertically around it. The horizontal pivot is the former-front-fork headstock bearing, left mounted in the front tubing off one of the Huffys, which is welded to the front of the trailer.

All I have to do to take the trailer off is use my tire-bolt wrench and loosen the nut on the stem, and it'll drop right off the stem, letting me ride off without the trailer when i need to, or quickly hook it up for runs to the store or to pickup stuff found on the lists.

It's a bit easier to see the bolt on the stem in this pic, and you can also see the two brackets on the sides of the hitch stem that keep any side-to-side stress off the welds there; I was afraid otherwise I might end up with them breaking or bending the tubing there (it's a bit thin, as it was only a lawn chair foot that it is welded to right now). Those brackets used to be the front-foot brackets on a washing machine, and are almost 1/8" thick steel. Kinda heavy, but they were right there when I was digging for parts. :-)

I'd like to put a bearing between the stem clamp and the cargo rack tubing, but that would preclude easy transfer of the hitch's bike-end to a different bike, which I could do in about 5 or 10 minutes right now. I decided on this particular hitch method after considering a few that would reach around the rear wheel to clamp or bolt to one of the side accessory holes, or frame, because this hitch can't hit the wheel no matter how tight the turn, and doesn't pull the bike in funny ways down low. It does make for a possible problem if wieght shifts too much to the rear of the trailer, behind the axles of the trailer wheels, because that could lift the stem up and the rear wheel of the bike could lose traction. So I have to watch the load on anything *really* heavy, like a couple hundred pounds or more.

To make this trailer the way I really want to, I'd need thicker tubing more like bike frame tubing, but i simply don't have enough of that available. Thus, the scrap computer desk tubing and the lawn chair tubing, which are probably only 1/16" thick at best. I burned thru them both in several places when I started welding it up, which wasn't encouraging, but I got better at it and fillet welded the holes afterward. Hopefully it'll still be as strong as I need it to be. :-) (I'd practiced mostly on bike frame pieces from bent-up frames, since most things I intend to weld will *be* bike frames).

Better pics will be added above and below as soon as daylight is good tomorrow.

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