Lights

Chris BeHanna said:

I suppose, for now, that I'd get a tire- or rim-driven unit, to save on
costs. How much wear on the tire does a tire-driven unit cause? I'm
already chewing up rear tires at a furious rate on the chipseal that
passes for roads around here.

I can't comment much on sidewall wear, because I've been using roller
(or bottom bracket) generators for decades. My folding bike has a
bottle generator, but I have very few night miles on it. The bottle
generators I've put on others' bikes don't seem to cause much problem,
though.

Quoted message said:

(I presume the drag is about equivalent to the light output, plus some
percentage for inefficiencies--say you get 5W or 6W of power loss at the
wheels to get 3W of illumination--does that sound right?)

That's the general idea. When people talk about the efficiency of a
generator, they're talking about that ratio of power lost to power fed
to the light. FWIW, 50% would be considered a very good efficiency.
Some efficiency data is available here:

http://www.myra-simon.com/bike/dynotest.html

- Frank Krygowski

The Wogster said:

Three hours is fine if your only riding for an hour or two, if however
you need to ride all night, then you need a really big honkin' battery,
and that can make for a very large, and heavy battery. Of course the
ideal is maybe to run both. A low power, close up, dynamo powered
light, and a longer distance battery powered "high beam", for when you
need to see stuff further away.

This is indeed ideal, if you do long night rides. A lot of the time the
dynamo light is sufficient, but occasionally you need to see more than
the dynamo light can illuminate.

SMS said:

I think one of the key points is that for $20 you can buy a Twofish
Cyclopblock, and a Maglite 2C flashlight, and have a far better
headlight than what you get with a $20 dynamo from a discount store (or
for that matter, even better than the Union Marwi systems at around
$35). Plus it's usable for other stuff, like repairs, and doesn't go off
when you stop, and is adjustable from spot to flood. Add a good LED
flasher and you're still under $50. Or get the Streamlight 51002 TT-3C
flashlight for around $10 more, and get both LEDs and a xenon bulb.

To follow up on this, I should have mentioned the ultimate
flashlight/bicycle light, the Streamlight Strion. I use one on my
folding bicycle because it was the best option that wouldn't interfere
with the folding (until I can get a wheel with a Joule hub dynamo).

This flashlight has excellent optics, with an adjustable spot to flood
beam. It is much brighter than a 3W dynamo powered headlight due to its
6W bulb and excellent optics. It uses a rechargeable Li-Ion battery,
which is a big advantage over NiMH cells, because the self-discharge
rate is very low. I used it last night, for the first time in about
three months, and it hadn't been on the charger, which would not have
been possible with NiMH cells left unconnected to a charger. It runs for
about 80 minutes per charge, which is sufficent for my commute.

It's $80, which is a lot, but there are no other flashlights that bright
that are small enough to put on your handlebars.
"http://www.streamlight.com/strion_info.htm"

The Streamlight Twin-Task 3C is another excellent light for bicycling,
featuring both LEDs and a xenon bulb.

The important thing is that you don't have to spend a fortune to get
good lighting. Both of these flashlight solutions provide a brighter and
more usable beam than the cheap dynamo systems sold at discount stores.

SMS said:

The Wogster said:

Three hours is fine if your only riding for an hour or two, if however
you need to ride all night, then you need a really big honkin'
battery, and that can make for a very large, and heavy battery. Of
course the ideal is maybe to run both. A low power, close up, dynamo
powered light, and a longer distance battery powered "high beam", for
when you need to see stuff further away.

This is indeed ideal, if you do long night rides. A lot of the time the
dynamo light is sufficient, but occasionally you need to see more than
the dynamo light can illuminate.

Kind of like when an cager uses "high beams", versus the low beams that
they use at other times. Where it gets interesting, is the situations
may be different, when you need high or low beams on a bike, versus when
you need them in a cage.

You would need a handle bar mounted switch for the battery light,
although I think that it needs to be an integrated system, where the
lights, dynamo and battery need to work together as a unit, rather then
a bunch of independant pieces. For example the dynamo light can pull a
little power from the battery when the generator output is less then
what's needed. The generator could supply some energy to the battery
rather then over-voltage the lamp when your doing a high speed downhill
run.

There are other issues though, like lamp technology, we all know that
the standard 2,4V flahlight bulb is inefficient, and that high
efficiency lamps need high start voltages, but pretty low run voltages,
given the amount of light output. So, an option could be using the
battery to provide the start, then run things off the generator, and
back to the battery when generator output falls below the amount needed
to run the lamp(s). Kinda like a UPS switches between line power and
battery power.

W

SMS said:

To follow up on this, I should have mentioned the ultimate
flashlight/bicycle light, the Streamlight Strion. I use one on my
folding bicycle because it was the best option that wouldn't interfere
with the folding (until I can get a wheel with a Joule hub dynamo).

This flashlight has excellent optics, with an adjustable spot to flood
beam. It is much brighter than a 3W dynamo powered headlight due to its
6W bulb and excellent optics. It uses a rechargeable Li-Ion battery,
which is a big advantage over NiMH cells, because the self-discharge
rate is very low. I used it last night, for the first time in about
three months, and it hadn't been on the charger, which would not have
been possible with NiMH cells left unconnected to a charger. It runs for
about 80 minutes per charge, which is sufficent for my commute.

It's $80, which is a lot, but there are no other flashlights that bright
that are small enough to put on your handlebars.
"http://www.streamlight.com/strion_info.htm"

:-) It would be hard for me to justify spending $80 for a flashlight
to kludge to my handlebars. Especially if I were the kind of guy
complaining that generators are too expensive!

"Up to 70 minutes" run time (that's their claim, not your 80 minutes)
would cover a lot of my night riding, I admit... but I worry about the
"Up to." I also worry about the time I'd forget to recharge it. And I
assume that Li-Ion batteries behave like other rechargeables, in that
the run time gradually decreases. How long before it's down to 30
minutes? Of course, I could carry a spare battery... but those cost
$35 plus shipping!

I also question the "excellent optics" claim. I don't doubt its optics
are excellent for a flashlight, but people need to realize that real
vehicle headlight beams are NEVER shaped like flashlight cones of
light. The only time that shape is accepted is for kludged bike
headlights!

Take a car, a motorcycle, a moped, even a lawn tractor or snowmobile
and shine the headlight at a wall. You won't see a circle of light.
You'll usually see a somewhat rectangular shape, where the light is not
wasted upward; instead it's spread evenly on the road surface.

Or take a $10 bike headlight run by disposable batteries - say,
something like http://tinyurl.com/ds37j - and you'll see the same
thing. The beam is shaped to fit the road, so light isn't wasted.

When I see a bike light that doesn't shape the beam to the road, I
figure it's a kludge. AFAIK, all modern generator lamps have optics
designed to make good use of the light output.

- Frank Krygowski

I submit that on or about 16 Sep 2005 09:43:03 -0700, the person known
to the court as [email hidden] made a statement
(<[email hidden]> in Your
Honour's bundle) to the following effect:

Quoted message said:

When I see a bike light that doesn't shape the beam to the road, I
figure it's a kludge. AFAIK, all modern generator lamps have optics
designed to make good use of the light output.

You can see this quite graphically here:
http://www.fa-technik.adfc.de/Komponenten/Scheinwerfer/vergleich.htm
courtesy of Andreas Oehler and Olaf Schultz.

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

85% of helmet statistics are made up, 69% of them at CHS, Puget Sound

I submit that on or about Fri, 16 Sep 2005 14:50:11 GMT, the person
known to the court as SMS <[email hidden]> made a statement
(<[email hidden]> in Your Honour's bundle) to
the following effect:

Quoted message said:

This is indeed ideal, if you do long night rides. A lot of the time the
dynamo light is sufficient, but occasionally you need to see more than
the dynamo light can illuminate.

For some values of "need". I like to have a headtorch to fulfil this
function, but it is absolutely not essential. If you genuinely feel
you can't see enough you always have the option to slow down a bit.

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

85% of helmet statistics are made up, 69% of them at CHS, Puget Sound

Just zis Guy said:

SMS said:

A lot of the time the
dynamo light is sufficient, but occasionally you need to see more than
the dynamo light can illuminate.

For some values of "need". I like to have a headtorch to fulfil this
function, but it is absolutely not essential.

And I've proven that for decades. I tried a "head torch" for a brief
while, but decided it wasn't for me.

By the way, in the US "head torch" may conjure old images of Michael
Jackson's commercial for Pepsi Cola. ;-)

- Frank Krygowski

"Zoot Katz" <[email hidden]> wrote in message

Quoted message said:

Properly situated, the roller contacts the shoulder of the tire, not
the sidewall. I've not worn out any tire by running bottle generators
after learning that. I think there are tires made with special tread
patterns in the area of roller contact but I can't find 'em now.

Here's a couple:
Continental Top Touring 2000's .
Nokian Hakkapeliitta W106's (These are studded tires. Those Finns know how
to make a winter tire!)

I'm guessing the tread pattern may help get get extra grip, particularly in
wet conditions.

Quoted message said:

SMS said:

What you really want is not just over-voltage protection, since this
simply dumps off the excess energy as heat, reducing the effiency.

One should not overstate the problem. Bike generators are
self-regulating to a very large degree. Many people use NO voltage
regulation with them, and do not blow bulbs. With a well-designed

Unregulated voltage out of a generator will not climb above 7V easily and
never above 8V, therefore you're not dumping more than a very little
energy as heat by cutting off the tops of the AC.

Quoted message said:

Quoted message said:

A
dynamo such as the LightSpin would be ideal, as it does not lose
effiency by dumping off excess energy as heat.

Sure it does. The lightspin is a very efficient, wellbuilt dynamo followed
by fancy electronics -- but the dynamo itself will have a voltage curve
like any other dynamo, therefore the electronics are dumping heat. It's
not an alternator.

Jasper

SMS said:

I was including the losses from the bridge rectifier to convert the AC
out of the dynamo, to DC. You'd be right around 80%, with a good design.
So with a 6W dynamo, you're losing 1.2W, which is unacceptable.

Oh, please. 1.2W is nothing.

Jasper

On Wed, 14 Sep 2005 10:43:45 GMT, Stephen Harding <[email hidden]>

Quoted message said:

SMS said:

Just zis Guy said:

known to the court as "mark" <[email hidden]> made a statement

[cheap bottle generator sets]

Quoted message said:

Quoted message said:

Quoted message said:

> Not reliable, no over voltage protection, difficult to attach, lousy
> optics. Just what are they sufficient for?

Millions of Dutch people, according to my observations :-)

This is true. The riding conditions in the Netherlands are such that you
can get away with a lot less in terms of lighting.

I visited the Netherlands a couple years ago and it got dark
every night for the three weeks I was there.

Seems a light would be useful at least for three weeks per
year.

*A* light, yes. If only because you're fined 50 bucks for not having one
or forgetting to turn it on when they're checking them at the start of
winter. However, cheap bottle generator sets are perfectly adequate for
going 20-25 km/h, especially in streetlit areas (which is pretty much
everywhere with buildings, these days). Blinkies are good enough to
satisfy the fuzz and most places in the city you don't need a light at
all. That said, at least 50% of bike traffic is lightless in the dark.

Jasper

you know? said:

I submit that on or about Tue, 13 Sep 2005 21:07:39 GMT, the person
known to the court as SMS <[email hidden]> made a statement
(<[email hidden]> in Your Honour's bundle) to
the following effect:

Quoted message said:

This is true. The riding conditions in the Netherlands are such that you
can get away with a lot less in terms of lighting.

Yes, the darkness in Holland is of a completely different character to
that in the rest of the world. I'm told they have a special moon,
made of cheese, to give light at night.

I know you jest, but seriously: talk to an astronomer about light
pollution in .nl some day. Even on moonless nights -- and *especially* on
cloudy ones -- it doesn't truly get dark.

Jasper

SMS said:

I'm wondering about the Joule hub dynamo that Dahon is using. I haven't
seen it offered anywhere other than on Dahon wheels, and not in the
U.S.. Dahon is only charging an extra $75 for the dynamo and lights.

Isn't that one of the internally geared ones? Those are inherently worse.

Jasper

Quoted message said:

None were anywhere near $100 (although the FER was a
closeout). All give very good light and very good reliability. All
have lasted for many years.

http://www.roseversand.com/rose_main.cfm?KAT_ID=0&PRD_ID=15926&spr_id=2&MID=0&CID=175

FER is currently 25 EUR or around US$30.

Jasper

On Wed, 14 Sep 2005 17:48:54 -0700, [email hidden] (Tom Keats)

Quoted message said:

Even the antiquated Union U-100 headlights (which I'm
currently using) have superior optics to any flashlight's.

If only because flashlights are *designed* to have a beam that's much
narrower than what you need on a bike.

Jasper

SMS said:

It is not just my opinion that the greater illumination, that the
brighter lights provide, is better. Look at the statements by Marty
Goodman, and Ken Kifer.

"Argument by authority" is also a logical fallacy, you know.

Jasper

On Fri, 16 Sep 2005 00:57:37 -0400, Chris BeHanna <[email hidden]>

Quoted message said:

(I presume the drag is about equivalent to the light output, plus some
percentage for inefficiencies--say you get 5W or 6W of power loss at the
wheels to get 3W of illumination--does that sound right?)

That's about right for a bottle generator, they're around 35-40% efficient
for the good ones. About Half of that is the tyre/generator interface and
the rest is frictional and electric losses.

Jasper

On Fri, 16 Sep 2005 00:18:12 -0700, Zoot Katz <[email hidden]>

Quoted message said:

Properly situated, the roller contacts the shoulder of the tire, not
the sidewall. I've not worn out any tire by running bottle generators
after learning that. I think there are tires made with special tread
patterns in the area of roller contact but I can't find 'em now.

Look for the ones with embedded reflective strips, especially cheap 37/622
ones. At least that's where I find them.

Jasper

In article <[email hidden]>,

Jasper Janssen said:

On Wed, 14 Sep 2005 17:48:54 -0700, [email hidden] (Tom Keats)

Quoted message said:

Even the antiquated Union U-100 headlights (which I'm
currently using) have superior optics to any flashlight's.

If only because flashlights are *designed* to have a beam that's much
narrower than what you need on a bike.

Those hi-powered, MR-whatever-bulbed lights pretty much
have the same [lack of] optics as flashlights.

cheers,
Tom

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