Commuter lights

I submit that on or about Mon, 1 Aug 2005 12:53:04 +0100, the person
known to the court as [email hidden]
(D.M. Procida) made a statement
(<[email hidden]>
in Your Honour's bundle) to the following effect:

Quoted message said:

Enough to be pleased with myself, but not so much that I get in trouble
for it... I guess around £100 would really have to be a sensible limit
on a bike priced at £430.

That will buy you the Nexus, plus a B&M Lumotec Oval and a 4D
Toplight. The build will push it over the budget.

Guy
--
http://www.chapmancentral.co.uk

"To every complex problem there is a solution which is
simple, neat and wrong" - HL Mencken

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

Quoted message said:

Quoted message said:

Quoted message said:

That's ignoring the electrics issues. Would a 5W bulb (approx 0.5A) work
at

all, or would it just sit there at 0.5A running cooler with only 6V
across
it?

Neither. Approx 250mA would flow (Ohm's law), and it would be fairly
dim. Power is proportional to the square of current, so the "watttage"
would be closer to 1.5W.

Garn. Did you miss the recent discussion on this? A bike dynamo is not a
constant voltage device - it's a fair approximation to a constant current
device, and that current is 0.5A for the standard '6v' ones.

cheers,
clive

Simon Brooke said:

[re: lumis]
negotiating a series of tricky tight turns over rocks and tree-roots. On
road? Very nice, of course, but not the right solution - unless you are
the sort of person who *always* remembers to charge their batteries.

I use a hub dynamo for short distance commuting, but for night time training
rides I find that there just isn't enough light, and I live in the flatlands.
Even in winter it's possible to get 30mph on even a gentle downhill if putting
in some effort and I find dynamo lights start to be insufficient when riding
unlit roads, with some oncoming traffic (so your eyes never fully adapt) at
20mph or more.

A 12W lumi works fine for me for this.

Arthur

--
Arthur Clune PGP/GPG Key: http://www.clune.org/pubkey.txt
The struggle of people against power is the struggle
of memory against forgetting - Milan Kundera

I submit that on or about 1 Aug 2005 15:52:03 GMT, the person known to
the court as Arthur Clune <[email hidden]> made a statement
(<[email hidden]> in Your Honour's bundle) to the
following effect:

Quoted message said:

Even in winter it's possible to get 30mph on even a gentle downhill if putting
in some effort and I find dynamo lights start to be insufficient when riding
unlit roads, with some oncoming traffic (so your eyes never fully adapt) at
20mph or more.

SON, two lights in series. No problem.

Guy
--
http://www.chapmancentral.co.uk

"To every complex problem there is a solution which is
simple, neat and wrong" - HL Mencken

Just zis Guy said:

Quoted message said:

Enough to be pleased with myself, but not so much that I get in trouble
for it... I guess around £100 would really have to be a sensible limit
on a bike priced at £430.

That will buy you the Nexus, plus a B&M Lumotec Oval and a 4D
Toplight. The build will push it over the budget.

Plus I'd have to buy the rims and spokes too.

At this stage I have to admit that my cognitive faculties have been
thrown into disarray by the confounding news that Joanna Newsom is now
apparently going out with Bill Callaghan, so I'm not really sure where I
am...

I dunno. I guess I'd have to see what one of them looks and feels like
in practice. At the moment The fact that that £60 or so will buy a front
and back light running on very bright LEDs that last 40 hours or so on a
single set of batteries means the hub system would have to be very good
to be worth it.

Will continue stroking beard...

Daniele

"D.M. Procida" <[email hidden]> wrote in
message
news:[email hidden]...

Quoted message said:

Will continue stroking beard...

Daniele

You have a beard? Oh, definitely a dyno then.

G.

I submit that on or about Mon, 1 Aug 2005 17:48:44 +0100, the person
known to the court as [email hidden]
(D.M. Procida) made a statement
(<[email hidden]>
in Your Honour's bundle) to the following effect:

Quoted message said:

Quoted message said:

That will buy you the Nexus, plus a B&M Lumotec Oval and a 4D
Toplight. The build will push it over the budget.

Quoted message said:

Plus I'd have to buy the rims and spokes too.

No, you can use the same rim. If you want a new wheel, bicycles.de
will do a pre-built one.

Quoted message said:

At this stage I have to admit that my cognitive faculties have been
thrown into disarray by the confounding news that Joanna Newsom is now
apparently going out with Bill Callaghan, so I'm not really sure where I
am...

http://www.bbc.co.uk/dna/collective/A3212740 and
http://www.hse.gov.uk/aboutus/plans/hscplans/plan0304-01.htm - yes I
can see why that would induce cognitive dissonance...

Quoted message said:

I dunno. I guess I'd have to see what one of them looks and feels like
in practice.

You are welcome to try mine if in the Reading area at any point.

Quoted message said:

At the moment The fact that that £60 or so will buy a front
and back light running on very bright LEDs that last 40 hours or so on a
single set of batteries means the hub system would have to be very good
to be worth it.

It is. Trust me on this :-)

Guy
--
http://www.chapmancentral.co.uk

"To every complex problem there is a solution which is
simple, neat and wrong" - HL Mencken

"D.M. Procida" wrote in message

Quoted message said:

Also, I guess that dynamos have changed since 1982, because the ones I
used around then, which pressed on the tyre making a racket, would slow
down a bike nearly as effectively as a brake. And it seems a shame to
expend my puny output for lighting when I can need it all for the road.

Interesting data on the drag of vaious dynamos at
http://www.myra-simon.com/bike/dynotest.html.

"Everyone (who doesn't use one) complains that dynamos slow you down. Well
okay, of course they do, but I suggest that the slowing down has more to do
with psychology than the actual power required to turn it. It takes energy
to make a noise, your energy. Add the lowering tone (eee becomes urrr) as
speed drops on a hill and it becomes hard not to believe this morale sapping
device is responsible blame for the pain in your legs and the sweat on your
brow! "

"All of the generators were easier to turn than riding up a 1 in 300 slope.
Another way of putting that is a rise of 18 feet per mile; and there's quite
a cluster of sidewall and hub-driven models around the 1/500 line, or 10 ft
per mile. If that's a hill I'm a Dutchman! Let's put this into another
context. Our 90kg (total) cyclist must produce about 70W to maintain 20 km/h
on the flat. If he turns on his dynamo he needs another 6W minimum, 14W
maximum. He can work a bit harder or slow to 19 km/h, 18 minimum. Now that's
not too bad is it?"

Mike Sales

in message
<[email hidden]>,

D.M. Procida (') said:

At this stage I have to admit that my cognitive faculties have been
thrown into disarray by the confounding news that Joanna Newsom is now
apparently going out with Bill Callaghan

[fx: snorts, adjusts wig, looks interrogatively at the Clerk of the
Court]

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; When all else fails, read the distractions.

Graham Dean said:

Quoted message said:

Will continue stroking beard...

Quoted message said:

You have a beard? Oh, definitely a dyno then.

Only sometimes, and until my girlfriend makes me take it off, at which
point I shave my head too.

Daniele

Just zis Guy said:

Quoted message said:

At this stage I have to admit that my cognitive faculties have been
thrown into disarray by the confounding news that Joanna Newsom is now
apparently going out with Bill Callaghan, so I'm not really sure where I
am...

http://www.bbc.co.uk/dna/collective/A3212740 and
http://www.hse.gov.uk/aboutus/plans/hscplans/plan0304-01.htm - yes I
can see why that would induce cognitive dissonance...

Different Bill Callaghan though, the one who produces malevolent,
unsavoury and sexually disturbing music under the name "Smog".

Quoted message said:

Quoted message said:

I dunno. I guess I'd have to see what one of them looks and feels like
in practice.

You are welcome to try mine if in the Reading area at any point.

Thanks, though I don't know when I might be. Maybe I will happen upon a
similarly-equipped Cardiff person in the meantime.

Daniele

Mike Sales said:

"D.M. Procida" wrote in message

Quoted message said:

Also, I guess that dynamos have changed since 1982, because the ones I
used around then, which pressed on the tyre making a racket, would slow
down a bike nearly as effectively as a brake. And it seems a shame to
expend my puny output for lighting when I can need it all for the road.

Interesting data on the drag of vaious dynamos at
http://www.myra-simon.com/bike/dynotest.html.

"Everyone (who doesn't use one) complains that dynamos slow you down. Well
okay, of course they do, but I suggest that the slowing down has more to do
with psychology than the actual power required to turn it. It takes energy
to make a noise, your energy. Add the lowering tone (eee becomes urrr) as
speed drops on a hill and it becomes hard not to believe this morale sapping
device is responsible blame for the pain in your legs and the sweat on your
brow! "

"All of the generators were easier to turn than riding up a 1 in 300 slope.
Another way of putting that is a rise of 18 feet per mile; and there's quite
a cluster of sidewall and hub-driven models around the 1/500 line, or 10 ft
per mile. If that's a hill I'm a Dutchman! Let's put this into another
context. Our 90kg (total) cyclist must produce about 70W to maintain 20 km/h
on the flat. If he turns on his dynamo he needs another 6W minimum, 14W
maximum. He can work a bit harder or slow to 19 km/h, 18 minimum. Now that's
not too bad is it?"

I also calculated that at an average output of 150W, the 6W drag of a
SON would get me from London Fields to Dunwich 7 minutes slower.

you know? said:

Good rechargeables are expensive as well, plus you have to remember to
charge them.

Plus they will need replacing after a time (I doubt that commuting is
particularly battery-friendly - long periods of non-use in the summer
inevitably result in self-discharge and temperature swings in the
winter...)

Plus the cost of the 'leccy to recharge them :o)

Clive George said:

Quoted message said:

Neither. Approx 250mA would flow (Ohm's law), and it would be fairly
dim. Power is proportional to the square of current, so the "watttage"
would be closer to 1.5W.

Garn. Did you miss the recent discussion on this? A bike dynamo is not a
constant voltage device - it's a fair approximation to a constant current
device, and that current is 0.5A for the standard '6v' ones.

I did try this with a 6V 5W halogen bulb and a Schmidt hub dynamo and an
interesting thing happened: because the Schmidt refuses to provide more
than 0.5A, the bulb filament never got hot enough to raise its
resistance to its normal running level and so it remained very dim
indeed, far dimmer than the constant-current maths would suggest.
(technical note: the short, thick filaments in halogen bulbs have a very
low resistance at room temperature which rises quickly when they heat up
to their normal operating conditions).

Chris
--
http://www.solidlights.co.uk/

I submit that on or about Mon, 01 Aug 2005 20:24:33 +0100, the person
known to the court as Chris Jones <[email hidden]> made a
statement (<[email hidden]> in Your Honour's bundle)
to the following effect:

Quoted message said:

I did try this with a 6V 5W halogen bulb and a Schmidt hub dynamo and an
interesting thing happened: because the Schmidt refuses to provide more
than 0.5A, the bulb filament never got hot enough to raise its
resistance to its normal running level and so it remained very dim
indeed

Heh! And that was unexpected in what way, precisely? That's lemon
entry physics, that is.

Guy
--
http://www.chapmancentral.co.uk

"To every complex problem there is a solution which is
simple, neat and wrong" - HL Mencken

I submit that on or about Mon, 01 Aug 2005 20:27:47 +0100, the person
known to the court as Chris Jones <[email hidden]> made a
statement (<[email hidden]> in Your Honour's bundle)
to the following effect:

Quoted message said:

Or a convenient twin 3W LED with standlight and flashing mode, all in a
single neat package ready to plug in...

Beam pattern? Looks interesting, but it will take some effort to
tempt me away from my SON E6s :-)

Guy
--
http://www.chapmancentral.co.uk

"To every complex problem there is a solution which is
simple, neat and wrong" - HL Mencken

Just zis Guy said:

Quoted message said:

Even in winter it's possible to get 30mph on even a gentle downhill if putting
in some effort and I find dynamo lights start to be insufficient when riding
unlit roads, with some oncoming traffic (so your eyes never fully adapt) at
20mph or more.

SON, two lights in series. No problem.

fx: <polite cough>
Or a convenient twin 3W LED with standlight and flashing mode, all in a
single neat package ready to plug in...

Chris
--
http://www.solidlights.co.uk/

"Chris Jones" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Clive George said:

Quoted message said:

Neither. Approx 250mA would flow (Ohm's law), and it would be fairly
dim. Power is proportional to the square of current, so the "watttage"
would be closer to 1.5W.

Garn. Did you miss the recent discussion on this? A bike dynamo is not a
constant voltage device - it's a fair approximation to a constant current
device, and that current is 0.5A for the standard '6v' ones.

I did try this with a 6V 5W halogen bulb and a Schmidt hub dynamo and an
interesting thing happened: because the Schmidt refuses to provide more
than 0.5A, the bulb filament never got hot enough to raise its resistance
to its normal running level and so it remained very dim indeed, far dimmer
than the constant-current maths would suggest. (technical note: the short,
thick filaments in halogen bulbs have a very low resistance at room
temperature which rises quickly when they heat up to their normal
operating conditions).

Ah - except the constant current maths suggests precisely this will happen,
doesn't it? (0.5A)squared * not very much R = not enough to heat raise the R
to running temperature. I wondered if something like this might happen with
the 12V 5W bulb too. Except the 12V bulb will have a higher resistance to
start with, so there will be more heating - certainly in a steady state the
dynamo should be able to drive a 12V 5W bulb as easily as 2x 6V 2.5W bulbs.

cheers,
clive

Clive George said:

Quoted message said:

I did try this with a 6V 5W halogen bulb and a Schmidt hub dynamo and an
interesting thing happened: because the Schmidt refuses to provide more
than 0.5A, the bulb filament never got hot enough to raise its resistance
to its normal running level and so it remained very dim indeed, far dimmer
than the constant-current maths would suggest. (technical note: the short,
thick filaments in halogen bulbs have a very low resistance at room
temperature which rises quickly when they heat up to their normal
operating conditions).

Ah - except the constant current maths suggests precisely this will happen,
doesn't it? (0.5A)squared * not very much R = not enough to heat raise the R
to running temperature. I wondered if something like this might happen with
the 12V 5W bulb too. Except the 12V bulb will have a higher resistance to
start with, so there will be more heating - certainly in a steady state the
dynamo should be able to drive a 12V 5W bulb as easily as 2x 6V 2.5W bulbs.

Indeed true, but it seemed to me at the time that the effect was worse
than my simple mental I2R model had predicted, because the positive
temperature coefficient of the bulb's resistance and the dynamo's
rapidly diminishing output with increasing current were working against
each other. I was disappointed, anyway ;-)

Chris

Just zis Guy said:

Quoted message said:

Or a convenient twin 3W LED with standlight and flashing mode, all in a
single neat package ready to plug in...

Beam pattern? Looks interesting, but it will take some effort to
tempt me away from my SON E6s :-)

The 1203D's beam pattern is a straightforward even circle with a fairly
well-defined edge. I freely admit that it's not as nicely optimised as
the E6's, but with so much more light available from the LEDs a bit of
overspill becomes an advantage. Some people like the cooler white colour
of LEDs compared with halogen bulbs, and of course the LEDs don't burn
out (not for 20,000 hours or so anyway).

The proof of the pudding is in the riding, of course, and I have several
customers who've upgraded from twin E6s to a 1203D and are delighted
with the results. Anyone near Cambridge is welcome to come and have a look!

Chris
--
http://www.solidlights.co.uk/