I have several Blackburn Quadrant bicycle headlights. I like the way it works. It has 4 bright white LEDs and several flashing modes. Unfortunately, the plastic clamp that holds the light on the handlebar is somewhat weak. I commuted to work with this light several times, and one day, the clamp just fell apart.
Step 1: What Will Fit Into That Channel?
So here I am with a great headlight, and no way to mount it onto my handlebars. I looked at the bottom, and it is simply a thin rectangular channel. What will fit into that channel?
Step 2: Answer: a Hack Saw Blade
A hack saw blade will fit into that slot, with a litle wiggle room. I used to just throw these away, but I started saving them, in case I could re-use them. Here is a great re-use for this blade.
If you don't have any hack saw blades, you can ask your neighbor, or your grampa; somebody will have one of these old blades. Or if you can find a piece of steel or aluminum that is exactly the same width and thickness, you can use that. It needs to be fairly stiff, but bendable.
Step 3: Determine the Correct Length of the Blade
You may have a different stem length than my bike, so you need to see how long to break the hack saw blade off - a couple of inches will probably be long enough. Remember that used hack saw blades are kind of brittle, so you only want to do this once.
I really only needed to make it long enough to reach back far enough to allow me to tape the back part down, tightly.
Step 4: Put Some Black Tape on the Hacksaw Blade
You need to wrap some black tape around the blade to make it friction fit into the Quadrant channel. You could paint the rest of the blade, white, silver, or whatever. I ended up just wrapping some black tape all the way down the blade, to keep it from rusting.
Step 5: Black-tape the End to the Stem
Notice here, where I black-taped the end to the stem, leaving the front part sticking out.
Step 6: Slip the Blade Into the Channel
Now, just slip the channel over the blade, and into place. You might have to tip the blade up slightly, and then down, to focus the beam on the road, and not up in the air, like I did.
To do this, just gently pull the blade up, then put a screwdriver under it, and then bend it down, with the screwdriver under it. This will put a slight bend into the blade. Don't do this too many times, or you will snap the blade in half.
Step 7: Finished Look -- Nice!
I forgot to mention the best part - when you mount the light like this, it will be positioned right in the middle of the handlebar, directly over the stem, not on one side of the stem or the other. It is more like a motorcycle and also frees up your available handlebar space for a cyclo-computer and a bell (or your hands), if you like.
Oh, and another benefit - if you only have one of these lights, but several bikes, you can put a mount on each bike, and simply stick the light on the bike you are riding that day!