Do you know what this is used for?

[Tarifa]

Older generations will know, younger generations might not.

[Sunrising]

The photo shows a dynamo that powers the lighting for a bike.

The problem is they wear the side of the tyre.

A much better system is having the dynamo in the wheel hub, but today with cheap led lighting that can be rechargeable, they are not worth the cost.

The photo also shows a brake block for rim brakes, and the problem with these are they wear the usually aluminum rim. There is sometimes a wear grove around the rim, and a constant check is required, so that the rim isn't worn beyond this grove.

Rim brakes are still popular, but disc brakes are gradually replacing them, and are a much better system of braking.

[Tarifa]

Great info. Yes, disk brakes would also provide much better stopping power.

These dynamos also made a funny noise when not correctly aligned. And they were useless when you had to stop at an intersection, which is probably one of those places where you need to be seen.

[Sunrising]

Thank you for the MHO.

[strateguy632]

Electric generator for light

[Tamera952]

I was going to say, it looks like something to hold your bottle of poppers while you ride your bike? …. but I’m guessing that’s probably wrong.

[Tarifa]

At night, you put this against the wheel of your bicycle. It generates enough electrical power while your bike is in motion to make the lights work. I think there was one at the front that made front and rear lights work. I don't recall having seen bikes with two dynamos. This goes back to my childhood days.

Nowadays, you'd expect LED lights to be powered by an individual battery.

[EmmaMary]

Isn't that a small dynamo which you attach to a bicycle wheel to generate power to some lights.

[Tarifa]

Yes, first answer and correct. You normally had two of these, one at the front and one at the back. It had a small lever so you could incline it against the bicycle wheels at night. It provided some friction, although minimal.

[EmmaMary]

Thank you for the MHO.

[Nikki1989]

It powers the lights.

[dudeinohio]

Electric generator.