On Thursday, 11 August 2016 08:58:59 UTC+1, harry wrote:
On Wednesday, 10 August 2016 11:46:05 UTC+1, David wrote:
The standard ways a

a hub dynamo (ridiculously expensive considering I had one on my bike in
the 1960s) but this needs a wheel rebuild as well as the purchase of the
hub.

a bottle dynamo (which is a pain to get to rub against the tyre when you
want it to and not when you don't). Also noisy and perhaps not very
efficient.

There was a dynamo a while back which fitted to the frame just in front of
the rear wheel and contacted the tread of the tyre instead of the side
wall but I haven't seen this around for a while. Cant locate it via Google
after a quick search.

I did wonder if there was another way. For example using a disc brake like
assembly, with a metal plate rotating through two fixed contacts (just
like a disc brake and pads).

For another example, having a light metal cover on the front wheel (like
the aero wheels on time trial bikes) and fixed contacts all the way up the
front forks.

Both (badly described) methods should provide the basic rotating split
ring and metal brushes of a DC generator. I just have no idea how
efficient this would be compared to a hub or bottle generator.

Of course, an adverse reaction to water and grit might play a part as well.




Bicycle generators are all AC.
Why would they need to be DC?
Have you never dismantled one?

Because LEDs run on DC not AC like filiment bulds so you'd be wasting half a cycle (dont forget it's a Bi-cycle) to only rectifcy half the wave.

But I still see little point in it.

be fun to put a wind turbine on the back and a solar panel.

But I;m not sure how effcient a dynmo is I've heard most aren't

I don't remmeber pro cyclist using them in compitition or for anything.