How to make a retro LED bike light

It's quite easy to come across very nice looking vintage bicycle lights. They usually are a part of an old dynamo system, which if working properly is a great addition to a bike, but often are completely non-functional. This is a step-by-step guide of how to convert these old dynamo lamps into modern LED battery powered lights for next to nothing. The conversion below cost me only £4 (€5) as I already had the old lamp from an even older bike I used to own.

Here's my chosen lamp. It's a sleek little streamlined thing! Originally this was made for a little 3w lamp bulb, but now it's getting something a little better installed.

The old bolt for attaching the dynamo wire will come in handy for placing a new switch on the body.

I'm going to install the innards of this £3 LED battery torch into the lamp.

Then use this little switch as the new controller.

After removing the old bolt that the dynamo wire used to attach to, the small switch fitted surprisingly well into the hole with no adjustments.

The torch has a switch built into the screw on end cap, this is no use for the new light it's going into, so it's going to be wired with the new switch instead. The black part is the battery holder for 3 AAA batteries.

One wire goes on the end of the battery holder.

And then to the switch.

I broke my trusty soldering iron out, and made a bit of a mess of it as I'm not very good at soldering! But it doesn't matter, because this is too easy to go wrong!

A second wire is soldered onto the other end of the battery holder.

I then hacked off the body of the torch to make it fit into the new housing.

Again by some strange luck, the head of the torch fitted perfectly onto the reflector of the vintage bike lamp.

The second wire I soldered onto the battery holder was then soldered onto the spring inside the torch head that the battery holder used to press against.

A third wire goes from the switch...

To the torch head body, which acts as the second connector in this torch's design (your mileage my vary). I drilled a small hole in the torch head to make sure the wire stays in place.

Done!

It lives! I was still genuinely happy not to have broken anything.

I covered everything in a bit of hot glue to reinforce it, and make it a little bit water proof.

The torch head got glued in place.

Then everything placed inside the old light body.

The switch installed nicely.

And there we have it, a super simple, crazy cheap vintage LED bike light to go on your ride. Keeps you safe and stylish.

I made a little clamp out of some random connectors I had from an old chain case, to give the light a test fit on my old Raleigh 3 speed. Overall I think it looks pretty great!

I will need to make a better bracket for it later as this didn't hold it very tightly, I'll probably also make it with quick release too so I don't get super sad if someone steals it sometime on the street. If I was making it again, I'd mount the LEDs further into the reflector to spread the beam out a bit more, but it still provides a very bright light to get you seen.

Good luck with your own light! It is honestly quite hard to get it wrong.