Finishing touches for the Speed Vest
With the electronics complete, there were only a few steps left to finish the Speed Vest. The digits had been sewn into a large piece of black denim cloth. It was now time to put this in a more attractive shape. After some consideration I decided to go with a trapezoid, as the original authors did. I wanted something that could be used without being attached to a jacket. It’s warm here now, and permanently attaching the Speed Vest to a jacket would limit its usefulness.
Since I don’t own a sewing machine, a friend of mine — Sherri — kindly offered to do the final stitching. But I had to pin the cloth into the proper shape for her. This took a surprisingly long time to do right. I quickly figured out that doing it “by eye” looked pretty awful. A template didn’t work too well either. In the end, I determined the bisecting line, then did precise measurements out from that to each edge. After a lot of pinning and repinning, the vest looked pretty decent:
The Speed Vest, pinned and ready for sewing.
Another small item, the wires for the wheel sensor needed to be made longer. The input from them goes into the back of a jersey or jacket rather than a computer at the top of the stem. It is a greater distance. So I broke out the heat shrink tubing and went to town. I have a 100′ spool of the stuff lying around — it was such a great deal, I couldn’t resist — and thought this would be a perfect use for it. As it turns out, there is a limit to how far you can push two wires through a single piece of heat shrink tube, but with two pieces of tubing I got the job done nicely. (The ability to extend power cords may be my favorite hacking trick thus far. I feel like the world is at my fingertips.)
The ribbon cable, by contrast, needed to be significantly shortened, so I cut it and crimped on a new connector.
Sherri did a beautiful job sewing, and one day turnaround no less. As a quick test, I attached the vest to a bike jersey and used the wheel sensor magnet to generate a reading:
Speed Vest test.
The only thing left to do is to take the vest out on the bike! I am planning to do this on our next Thursday night ride.
UPDATE: Some people have pointed out that in this photo, the corners seem very sharp. This is due to the very hasty safety pin job I did, it had been a long day and I just wanted to get the picture. The vest is soft and can match the rounding of my shoulders when attached properly.