Generator light optics

Mon, 11 Oct 2004 21:35:00 -0500,
<1097627762.2E6blN3SeARIiYRO7L/vFQ@teranews>,
"Mike Kruger" <[email hidden]> concluded:

Quoted message said:

So:
-- Any simple way to improve the light output?
-- I'm assuming these generators work with newer lights (thus getting better
optics) as long as I match 6 volt, 2.4 watt, but if anybody has experience
to the contrary I'd be happy to hear it.

Try using a 3W krypton bulb in the front and running a battery powered
tail light. A three watt bulb is noticeably brighter in the same lamp.
--
zk

[I copied r.b.tech with my reponse.]

Mike Kruger said:

Are there any simple ways to improve the light output of old
Schwinn-approved generator sets?

I have a nice bottle genertor (Busch and Muller Dymotec S6) and light
(Bisy) -- 6 volt, 3 watt (no rear light).
This is described at:
http://peterwhitecycles.com/dymotec.asp
When I use this with an auxiliary light (one of those Cateye halogens that
use 4 AA batteries), the generator light is far brighter than the Cateye.
(Just like Frank K is always posting.)

But, alas, the state of the dollar versus the euro makes these things much
more expensive than they used to be. I also have been doing some bike
salvage, and have ended up with a handful of generators off old Schwinn
bikes.

I can tolerate the added drag on bikes where I don't expect to use the
generator much, but the light is much dimmer -- "be seen" quality, and much
dimmer than the Cateye. Part of this is due to the lower wattage (6 volt,
2.4 watt with rear light) but I suspect the rest is due to the bulb
(standard versus halogen) and the reflector optics.

So:
-- Any simple way to improve the light output?
-- I'm assuming these generators work with newer lights (thus getting better
optics) as long as I match 6 volt, 2.4 watt, but if anybody has experience
to the contrary I'd be happy to hear it.

So, to make sure I have it clear: you're trying to put together another
generator set for a second bike, and do it inexpensively.

It's true that generator output doesn't change much across different
brands. As I understand, German standards ensure that.

And in my experience, generator lamps have widely variable optics among
the different brands. Bulbs also vary, depending on type.

You could try putting a good halogen bulb for the lamps you have. I
once put a 2.4 watt halogen bulb into a dirt cheap department store
generator for a friend's bike. I was surprised and impressed with the
light output and the optics. You may be able to find a 6 volt, 2.4 watt
halogen bulb at a "good" bike shop - one with fenders on display instead
of carbon fiber cranks! It'll cost less than $7.

Of course, you can get bulbs from the same sort of shops via mail order.
Peter White, http://www.peterwhitecycles.com/lightingsystems.htm
and Sheldon's Harris Cyclery
http://sheldonbrown.com/harris/lighting/lumotec.html
don't seem to mention bulbs, but I bet if you e-mailed, they'd sell you
one. If not, Reflectalite http://www.reflectalite.com/ definitely has
them.

The next level of improvment would be to use a better headlight. I've
got three different models of Union lamps that I've used, and each is
different in its optics, so you might want to try some trial and error.
Of course, those $20 Lumotecs at Sheldon's site ought to do the job,
and of course, they come with a bulb.

Further details: Don't neglect to double-wire the headlight. That is,
don't rely on the bike frame as a ground. And finally, the position of
the light makes a difference. I like it best when the light's mounted
about 24" to 27" above the ground and far enough forward to not be
blocked by the tire. I made a rack to hold it there, above the front of
the tire.

I still haven't gotten around to using a 3W bulb in my lights. I do
have a switch on my generator taillight, and I can switch it off. This
overdrives the 2.4 watt headlight and brightens it noticeably. So far,
no problems with bulb life. (I do have back-to-back Zener diodes in the
circuit for some overload protection.)

--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]

"Frank Krygowski" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

So, to make sure I have it clear: you're trying to put together another
generator set for a second bike, and do it inexpensively.

Yep; the B&M S6 generator with the Bisy light (good stuff) is on the bike I
would ordinarily use in the dark;
This setup would be for a lightly used bike (pun intended).
I'd also like to put these on my daughters' bikes -- they seldom ride in the
dark, and if they are late at the college library I doubt if it bothers them
much if they forgot the bike lights Dad gave them. The cheap generator's
always there, and not much of a theft magnet.

Quoted message said:

You could try putting a good halogen bulb for the lamps you have. I
once put a 2.4 watt halogen bulb into a dirt cheap department store
generator for a friend's bike. I was surprised and impressed with the
light output and the optics. You may be able to find a 6 volt, 2.4 watt
halogen bulb at a "good" bike shop - one with fenders on display instead
of carbon fiber cranks! It'll cost less than $7.

Good idea

Quoted message said:

Further details: Don't neglect to double-wire the headlight. That is,
don't rely on the bike frame as a ground.

Yes, the cheap generator/light combo is single wired. I thought that would
be sufficient on an all-steel bike.

--
Mike Kruger
The road to hell is now paved with PowerPoint presenations.

In article <1097632859.4WEP0NTtyME6ziqcb29aPg@teranews>,

Mike Kruger said:

Quoted message said:

Further details: Don't neglect to double-wire the headlight. That is,
don't rely on the bike frame as a ground.

Yes, the cheap generator/light combo is single wired. I thought that would
be sufficient on an all-steel bike.

I've found single-wiring is never good enough in the rain;
it loves too much to short out. Besides, it punches holes
through paint and does nasty stuff to frame material.

For double-wiring I like used-&-limp, black lamp cord. It
stays put in the wiring path so very well. It's a lot more
relaxed than a coil of new, plastic insulated, colour-coded,
2-conductor from Radio Shack.

I'll also second Frank's suggestion of trying various headlights.
I still like the 'traditional' Union light -- the old 4" diameter
one with the vertical, fresnel-like striations in the lens, with
a little bas-relief 'U' at the top. Interestingly, it seems to
also serve as a pretty good front reflector in daylight. But I've
had good luck with other headlights. Well, the cheap, plastic
toy, CCM one from Canadian Tire. It's actually not a bad headlight.

My current supply of lamps is slightly underrated; like, 5.8 volts
or something like that. They seem to burn a little brighter than
the usually recommended lamp, but they don't last as long. I
might go through 2/year. They have the same base and spherical
glass globe as the 'correct' lamp. Unfortunately I can't find
the box they came in, so I can't tell you the exact ratings
right now (it's not stamped on the bases of the lamps.) But I'll
look for it. It's around here somewhere.

Speaking of tire-rubbing generators in rain -- skipping. That
seems to be at least in part a function of the robustness of
the mounting bracket. Cheap, stamped-metal brackets are just
too bendy. Stouter, tempered steel is called for. It might not
hurt to temper it yourself, with a Bernz-O-Matic propane torch.
Provided the spring that holds the generator wheel against the
tire is tempered enough, itself. In my experience there can
be a sweet spot on the tire where the generator wheel contacts,
and it might take mere micrometer adjustments to get it there.
It can take a little fiddling around to get a tire-driven
generator working properly, but it can be done.

cheers,
Tom

--
-- Nothing is safe from me.
Above address is just a spam midden.
I'm really at: tkeats [curlicue] vcn [point] bc [point] ca

On Mon, 11 Oct 2004 21:35:00 -0500, "Mike Kruger"
<[email hidden]> wrote in message
<1097627762.2E6blN3SeARIiYRO7L/vFQ@teranews>:

Quoted message said:

I have a nice bottle genertor (Busch and Muller Dymotec S6) and light
(Bisy) -- 6 volt, 3 watt (no rear light).

Seems good to me.

Quoted message said:

But, alas, the state of the dollar versus the euro makes these things much
more expensive than they used to be. I also have been doing some bike
salvage, and have ended up with a handful of generators off old Schwinn
bikes.

Solution: check the price of a SON hub dynamo; everything else will
look suspiciously reasonable by comparison :-)

Quoted message said:

I can tolerate the added drag on bikes where I don't expect to use the
generator much, but the light is much dimmer -- "be seen" quality, and much
dimmer than the Cateye. Part of this is due to the lower wattage (6 volt,
2.4 watt with rear light) but I suspect the rest is due to the bulb
(standard versus halogen) and the reflector optics.

Try the B&M Lumotec Oval headlight with 2.4W halogen lamp (has a
blue-white LED standlight, as well, which is cool). Oh, and clean all
the contacts and maybe replace the cables if you haven't already.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

Tom Keats said:

Speaking of tire-rubbing generators in rain -- skipping. That
seems to be at least in part a function of the robustness of
the mounting bracket. Cheap, stamped-metal brackets are just
too bendy. Stouter, tempered steel is called for. It might not
hurt to temper it yourself, with a Bernz-O-Matic propane torch.

Hmm. I'm not optimistic about being able to temper the steel used in
most brackets, especially for an amateur using a propane torch.

To temper (or, more properly, heat treat) steel, it's got to have enough
carbon content to be classed as "medium carbon." Things like those
brackets are usually made of low carbon steel. You can try heating one
up to red heat then quenching it, but I doubt it will harden.

It might be easier to just make your own stouter bracket. Get the
strength with more thickness or a stronger shape, rather than by heat
treating.

Quoted message said:

Provided the spring that holds the generator wheel against the
tire is tempered enough, itself. In my experience there can
be a sweet spot on the tire where the generator wheel contacts,
and it might take mere micrometer adjustments to get it there.
It can take a little fiddling around to get a tire-driven
generator working properly, but it can be done.

I have one friend who's sidewall generator slipped badly in the rain, at
least on one ride. I don't know how well it's adjusted, though.

Some generators have (at least, as options) rollers made differently -
sort of like wire brushes - to cut through the water on the tire's side
and grip in the wet. I've never experimented with such a thing, but it
wouldn't be hard to modify or replace the roller that runs on the
sidewall of a tire.

For most of the past 15 years, I've used a bottom bracket generator, the
kind that rolls on the tire's tread. I've had a few incidents of minor
slipping, but only when I've ridden through wet mud.

Maybe my generator pushes pretty hard on the tire.

--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]

"Frank Krygowski" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Some generators have (at least, as options) rollers made differently -
sort of like wire brushes - to cut through the water on the tire's side
and grip in the wet. I've never experimented with such a thing, but it
wouldn't be hard to modify or replace the roller that runs on the
sidewall of a tire.

My "good" B&M S6 generator came with two wheels, one of which is like a wire
brush.
The good news: works well in rainy conditions.
The bad news: tends to eat up the tire, especially if the generator gets a
little bit out of radial adjustment, so you are "scrubbing" the tire.
It would be nice if this was designed so you could change wheels while
riding, but the wheel is held in place by a tiny clip, and it's hard enough
to change on a lighted workbench with a clean floor; changing it on a dark,
rainy night would likely lead to the loss of the tiny clip -- and no way to
attach either wheel.

--
Mike Kruger
The road to hell is now paved with PowerPoint presenations.

In article <[email hidden]>,

Frank Krygowski said:

I have one friend who's sidewall generator slipped badly in the rain, at
least on one ride. I don't know how well it's adjusted, though.

Some generators have (at least, as options) rollers made differently -
sort of like wire brushes - to cut through the water on the tire's side
and grip in the wet. I've never experimented with such a thing, but it
wouldn't be hard to modify or replace the roller that runs on the
sidewall of a tire.

For most of the past 15 years, I've used a bottom bracket generator, the
kind that rolls on the tire's tread. I've had a few incidents of minor
slipping, but only when I've ridden through wet mud.

Maybe my generator pushes pretty hard on the tire.

If I had a display stand to lift my rear wheel off the ground,
I could stick a shallow tub of water under the tire and watch
what happens to make a generator roller slip. I hypothesize
that what happens is: water accumulates and builds up a pressure
at the leading edge of the roller/tire contact, and eventually
some of that pressurized water squirts through with enough force
to lift the roller off the tire. Slowing down the tire's rpms
might allow the roller to regain traction.

If that is the case, maybe rollers whose striations let excess
water through while still maintaining traction with the sidewall
would eliminate slipping. Perhaps a 'wire brush' roller does
the same thing. I suspect that 'sweet spot' I was talking about
is a place on the tire where its texture either allows excess
water through, or somehow prevents water from building up in front
of the roller in the first place.

At any rate, I just can't imagine a mere thin film of water by
itself causing a generator roller to slip; I think there must
be other effects at work.

Darn it, now I'm curious. I'm gonna look for a display stand.
I've been wanting one for a while anyway.

cheers,
Tom

--
-- Nothing is safe from me.
Above address is just a spam midden.
I'm really at: tkeats [curlicue] vcn [point] bc [point] ca

Tom Keats said:

In article <[email hidden]>,

Frank Krygowski said:

I have one friend who's sidewall generator slipped badly in the rain, at
least on one ride. I don't know how well it's adjusted, though.

Some generators have (at least, as options) rollers made differently -
sort of like wire brushes - to cut through the water on the tire's side
and grip in the wet. I've never experimented with such a thing, but it
wouldn't be hard to modify or replace the roller that runs on the
sidewall of a tire.

For most of the past 15 years, I've used a bottom bracket generator, the
kind that rolls on the tire's tread. I've had a few incidents of minor
slipping, but only when I've ridden through wet mud.

Maybe my generator pushes pretty hard on the tire.

If I had a display stand to lift my rear wheel off the ground,
I could stick a shallow tub of water under the tire and watch
what happens to make a generator roller slip. I hypothesize
that what happens is: water accumulates and builds up a pressure
at the leading edge of the roller/tire contact, and eventually
some of that pressurized water squirts through with enough force
to lift the roller off the tire. Slowing down the tire's rpms
might allow the roller to regain traction.

If that is the case, maybe rollers whose striations let excess
water through while still maintaining traction with the sidewall
would eliminate slipping. Perhaps a 'wire brush' roller does
the same thing. I suspect that 'sweet spot' I was talking about
is a place on the tire where its texture either allows excess
water through, or somehow prevents water from building up in front
of the roller in the first place.

At any rate, I just can't imagine a mere thin film of water by
itself causing a generator roller to slip; I think there must
be other effects at work.

Seems to me it's classic aquaplaning, as with a car tire. The leading
edge of contact is running over water faster than the water can be
dispersed (sideways, for instance), so the water "floats" the generator
wheel. More contact force would help, because it would generate more
pressure in that water film, allowing it to squirt out of the way faster.

Another option would be to change the shape of the generator wheel. As
has been pointed out on r.b.tech many times, bike tires aren't very
prone to aquaplaning because their toroidal shape gives a "canoe-shaped"
contact patch that cuts through the water film. But most generator
wheels are cylindrical.

I've thought about machining a circumferential groove in a generator
wheel and putting a thick O-ring into it, to let the O-ring run on the
tire. (In fact, ISTR getting a glance at a generator that seemed to
have something like this running on the rim's braking surface, rather
than the tire.) I was thinking about reducing friction losses at the
tire-generator contact point, but it might reduce slip too.

--
Frank Krygowski [To reply, remove rodent and vegetable dot com.
Substitute cc dot ysu dot
edu]

Frank Krygowski said:

I've thought about machining a circumferential groove in a generator
wheel and putting a thick O-ring into it, to let the O-ring run on the
tire. (In fact, ISTR getting a glance at a generator that seemed to
have something like this running on the rim's braking surface, rather
than the tire.)

There are quite a few generators with such a roller. Nordlicht, for
example, which is probably the one you saw. Some people run it on the
rim, some on the tyre.

Busch und Muller make a weatherproof *wire brush* roller for their
bottle generators. It's not advisable unless the tyre has a proper
dynamo track, as it will certainly eat through a skinwall, and probably
a plain gumwall, in no time.

Zog The Undeniable said:

Busch und Muller make a weatherproof *wire brush* roller for their
bottle generators. It's not advisable unless the tyre has a proper
dynamo track, as it will certainly eat through a skinwall, and probably
a plain gumwall, in no time.

I have the Busch & Muller generator, but have never had the need
for the wire brush roller. The generator has a tension adjuster
that seems to do the trick for keeping drive roller firmly against
the wheel.

Sometimes bad bumps will cause a slight dimming of light but nothing
to really complain about.

It's a very impressive generator! Even more impressive is the
Lumotec 3W light! A very focused beam makes all the difference
for road commuting this time of year and once DST goes away in
another couple weeks. Wouldn't have thought a "mere" 3W would
be so bright.

SMH

A couple of weeks ago I asked "Are there any simple ways to improve the light
output of old Schwinn-approved generator sets?" The one I rescued from
the trash bin was so much less bright than my other, "very good but
expensive" generator (Busch and Muller Dymotec S6 and Bisy light).
Here's what I did based on your advice.

Wiring: I rewired the front light using the double wire from an old charger.
This double wiring meant I was not depending on the steel frame for a
ground.

Bulb: I had trouble finding what I wanted locally, so I ordered some 6V
3W screw-in halogen bulbs from Reflectalite
http://www.reflectalite.com/
This change from 2.4W front, 0.6W rear to 3W front meant that I
disconnected the rear red light, but I prefer a blinking red light anyway.

My initial test was before a full moon. With just the wiring
change, the light would not even wash out the shadows from the moonlight
until very close to the bike. With all the changes, the light is much
brighter, and has gone from "be seen" quality to being suitable for
urban biking. I hope not to be able to make any statements about bulb life
or any side effects of the change to a halogen bulb for quite a while 😉

The illumination is not as nice as my Bisy light (similar to a Lumotec).
This is probably because there is more scatter.
However one purpose was to improve the light for my college daughter;
she's had one bike stolen and her bike has been partially stripped
twice. I don't think the old Schwinn-approved generator setup is much of
a thief magnet, but I fear a good-quality German light would be. I think
this solution will work fine for her.

Thanks to those who posted.

In article <[email hidden]>,

(Mike Kruger) said:

Wiring: I rewired the front light using the double wire from an old charger.
This double wiring meant I was not depending on the steel frame for a
ground.

2-conductor Lamp cord works nicely too. Unless it's that
horrible brown colour. Lamp cord is nice & relaxed when
it's well aged.

Tinning the ends seems to make hooking-up more difficult
than just leaving the ends naked.

I've learned the hard way that grounding to the frame can be
prone to intermittency in the rain.

Quoted message said:

Bulb: I had trouble finding what I wanted locally, so I ordered some 6V
3W screw-in halogen bulbs from Reflectalite
http://www.reflectalite.com/
This change from 2.4W front, 0.6W rear to 3W front meant that I
disconnected the rear red light, but I prefer a blinking red light anyway.

Might as well disconnect the rear light. If the front bulb does
burn out, it takes the rear bulb out with it (assuming simple
wiring with no voltage protection.)

cheers,
Tom

--
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Above address is just a spam midden.
I'm really at: tkeats [curlicue] vcn [point] bc [point] ca