Tuesday, May 19, 2009

Running Boards

The highlight of my respite weekend was making running boards for the Yuba in my pastor's shed. I wanted running boards because my sack of onions often falls mostly through by the time I get it home from the market, but it actually happened because it's a pre-requisite for a future project. There is a downside risk that I can't put the wheel of another bike through the wings when towing like I used to, but I have a couple of options if that really proves troublesome. I do like the increased visibility (and always wanted the red model anyhow).

My pastor generously donated a plywood offcut, and had the suitable tools for the job. I started by tracing the front and back curves of the sideloaders onto the wood, far enough apart to allow overlap for the clamps I attached it with (more on the clamps below). Conveniently the sideloaders have a long straight edge to align the ply against. After cutting the shapes out with a jigsaw, I found the band sander very useful for smoothing up the amateur-hour result and balancing the curves nicely.

I was surprised by how easy it was to get a passable shape. The front and rear of the sideloaders both have short straight sections on them, and I found it helped to establish them on the sander before working on the curves. With the straight edges established, I was able to smoothly transition from one to another, shaping the curve by the pace of rotation. It also helps not to lean too hard on the thing, taking longer but making mistakes less severe and easier to sand out.

Drilling the holes and painting were pretty straightforward, although one set of holes only just worked for me. The plywood surface cracked slightly when the bit emerged, so I drilled a small hole from the back where I'd marked the placement and then the full size hole from the front to the back. There was a similar problem when I tightened the bolts down hard and the plywood surface cracked a bit.

I attached these boards with basic u-shaped clamps. They were fairly simple to use, but I had a limited choice of sizes and the ones that weren't too large fit so tightly that I had to completely remove them to adjust their position slightly. They also cut somewhat into the layer of electrical tape I put on to protect what remains of the paintwork. I found that I had to use a longer screw on one end of each clamp, athough I could remove that after tightening everything up bent the clamp into submission. This is probably partly due to poor hole placement and partly to poor size matching.

My choice of clamp meant that I needed to leave overlap at the front and back. This works okay for me, but will probably cause occassional heel strike. It only happens when I let my heels sink as the pedal rises back up, which I think I do when I ease off after standing up. I've seen some running boards on Flickr (no time to find right now) which look like they are screwed directly into the tubing (which I'm nervous of) or possibly into single-bolt clamps which wrap right around the tube. Something you might want to consider if you're making your own.

The plywood we had to hand was only 150mm wide, but it seems to work nicely enough. The 12mm thickness looks to have provided sufficient strength; the long unsupported edge does flex a bit, but I expect the boards to stop things slipping through and provide comfortable foot placement rather than hold great weight at any one point. The wood was exterior grade, but lacked a nice finish (hence the effort to paint it). The paint is a simple water-based acrylic.

I'll try to update on how it's going after a period of genuine use - haven't even had it out on the roads yet, as I've reverted to my fixie for more intense cardio and (hopefully) fat burning.

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