If you commute regularly on your bicycle, the lack of sun in the winter can be a bit intimidating, particularly if your journey is not well lit. I ride my bike to work all year around, and in November, much of my commute is in the dark. I have a good set of lights (front and rear) to see where I'm going, but in the dark, people often don't notice hand signals. And of the folks that notice, many don't understand. I guess the left turn signal is pretty straight forward, but nobody really seems to get the right. And forget about stop and slow down... but I digress.
My goal is to create a very simple set of turn signals that anyone can build with a few basic tools. Where possible, I've used commercial, off-the-shelf parts, all of which should be available at your local bike shop, electronics shop, or online if you don't have access to these things in your town.
The recommended way to indicate turning is by using hand signals, and these shouldn't replace that. These are rear turn signals only. You still need to indicate you intention to turn to the people ahead of you.
Step 1: Required Parts
1- Two Rear flashing bike safety lights: $10.50 each
I used Blinky7 lights from Planet Bike. I got them from Mountain Equipment Co-op here in Canada. Probably REI in the US would have the same thing. Important: The lights must have a blinking mode, and the blinking must be sustained when the batteries are removed, and put back in. The lights I used have a capacitor that slowly discharges. This means that if I don't use my turn signals for 20 minutes, the light gets reset to a solid light and I have to press the switch on the light to set it back to blinking mode. Ideally, your light will have a switch that will remember the blinking setting indefinitely.
2- One AAA x2 battery holder : $1. Get one with a case to keep the batteries dry.
3- One Double Pole Double Throw (or DPDT On/Off/On for short) switch. $5.50
I picked up both of these items at Lee's Electronic - my goto shop for electronics in Vancouver. Probably Radio Shack would have something similar. My battery case has an on/off switch, but that's not really required, as the switch will be used to turn them off. If you can find a waterproof switch, that would be ideal.
4- Wire. Red and Black. 6 feet of each should do, or enough to go from your handlebars to the just at the top of the seat stays and back. 26 gage or so should be fine, but anything reasonable will work.
5- one extra long screw that will fit the nut of the Blinky mounting setup.
6- a little silicon , similar to the stuff that you would use to seal around your bathtub. Caulking, Shoe Goo, or Goop will also work.
7- A little strip of adhesive Velcro (both sides)
8- Solder and a solder iron. Or you could use silver conductive epoxy if you don't have access to a soldering iron.
9- Xacto knife
A set of helping hands (the mechanical device, not another person), and a set of wire cutters were also used, but you could get by without them.