On Thursday, December 20, 2001 at 3:28:25 PM UTC-8, Henry Law wrote:
I checked the FAQ and the Google archive without finding very much
about dynamos (which surprised me), so here goes my first post to
rec.bicycles.tech ...

My wife's bike (gash, heavy traditional touring bike about twenty
years old) has a tyre-driven dynamo which consists of an aluminium
bottle-shaped body with, at the top of the "neck", a knurled wheel
which rubs on the tyre; connections to the lights come out of the
bottom of the bottle. By way of maker's marks there is just a "U",
plus stuff about being made in Germany, but my review of newsgroup
postings suggests that it's a "bottle dynamo", possibly made by Union?

There are two problems with it: (1) it makes a noise like an air-raid
siren when in use (only a slight exaggeration); (2) it adds enough
resistance (says my not-unfit wife) to turn the machine into an
exercise bicycle. Power output is fine, though. I have an identical
unit on my bike, which is much quieter and adds only a little
resistance.

I've taken the "bottle" off, undone the only visible nut, securing the
knurled wheel in position, and done the usual sort of cleaning and
greasing, without obvious effect.

Is there any other maintenance I can do on the thing that might cure
the problem?
--
Henry Law
I used to be
Manchester, England but I had to move because of spam

There are methods as Andrew mentioned but those bottle generators are extremely inefficient. Hub generators are where it's at. Look at this which is dirt cheap and you would have to have it built into a wheel which would still make it cheap. https://www.ebay.com/itm/Nukeproof-G...AOSwunhfGeZ O