Hub Dynamo Lights?

Elisa Francesca Roselli said:

The bike by the firm Giant that I was looking at over the weekend, as an upgrade for my current
cheap-and-cheerful first bike, had front and back lights that were powered by a hub dynamo.

In Cambridge over the summer on my rented bike, I had experience of a light powered by rim-dynamo
and absolutely _loathed_ it. It was not just unreliable, only going on when I was pedalling fast
and thus failing at critical intersections whenever I slowed down, but drained so much power from
the bike that I could scarcely manage it on pancake-flat Fenland terrain.

Yes, I remember those. Analytically, I don't think they drain all that much power in terms of watts.
But psychologically they're a drag (ha!)--that whine as you're tooling down Queens' Road on your way
to the Seeley (OK, *my* way to the Seeley) is pretty frightful.

That said, when they were working, I never lacked lights when I needed them, which is more than I
can say for battery-lights. Unfortunately, since here in America nobody actually uses their
bicycles, there are no dynamo-driven lights to be found anywhere (except for extremely cheap dynamo
sets--who buys these?--at X*Mart).

-Luigi contrarian

Quoted message said:

I decided that I would avoid dynamo lights forever and, on returning, had my home bike fitted with
a very expensive and bright front light powered with a heavy rechargeable battery pack.

But the salesman told me that this power-draining effect of the rim-dynamo did not apply to dynamos
powered from the hub. Can anyone comment or confirm?

Many thanks Elisa Francesca Roselli Ile de France

Elisa Francesca Roselli said:

The bike by the firm Giant that I was looking at over the weekend, as an upgrade for my current
cheap-and-cheerful first bike, had front and back lights that were powered by a hub dynamo.

[snip]

Quoted message said:

But the salesman told me that this power-draining effect of the rim-dynamo did not apply to
dynamos powered from the hub. Can anyone comment or confirm?

I've been running a Shimano NX30 hub dynamo for the last few years. I think it's excellent.

Hub dynamos are heavier than bottle dynamos, and have a little drag even with the lights off, but
tend to be more reliable (especially in the wet), more efficient when in use, and aren't sensitive
to alignment as rim- or tyre-driven dynamos tend to be.

I use mine to drive either one or a pair of headlights. I run a separate LED rear light.

There's a detailed article on dynamos here:

myra-simon.comdynotest.htmlOpen ↗

The Shimano Inter-L tested is the old NX10 model, which has been replaced by the more efficient
NX30. Shimano is launching a new 'sports' model in Germany this autumn, promising further
improvements in efficiency.

James Thomson

"Elisa Francesca Roselli" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

The bike by the firm Giant that I was looking at over the weekend, as an upgrade for my current
cheap-and-cheerful first bike, had front and back lights that were powered by a hub dynamo.

In Cambridge over the summer on my rented bike, I had experience of a light powered by rim-dynamo
and absolutely _loathed_ it. It was not just unreliable, only going on when I was pedalling fast
and thus failing at critical intersections whenever I slowed down, but drained so much power from
the bike that I could scarcely manage it on pancake-flat Fenland terrain. I decided that I would
avoid dynamo lights forever and, on returning, had my home bike fitted with a very expensive and
bright front light powered with a heavy rechargeable battery pack.

But the salesman told me that this power-draining effect of the rim-dynamo did not apply to
dynamos powered from the hub. Can anyone comment or confirm?

Dynamo hubs still have an extra load; those 3-6 watts are being generated from somewhere, no matter
where the dynamo is located.

The bigger problem with dynamo systems is that the dynamo only generates 3 watts (there is one 6
watt dynamo available). In the U.S. anyway, a 3 watt lighting system is woefully inadequate.

The reality is that you can buy a high power rechargeable system for far far less than a quality
dynamo system. A 6 watt dynamo system will cost well over $300.

Dymotec S12: $247 Headlight: $ 64 Taillight: $ 54

peterwhitecycles.comdymotec.aspOpen ↗

I agree that there is a lot to be said for not bothering with batteries, but this is just too
expensive. I can build a high brightness, rechargeable battery, lighting system for about $50.

nordicgroup.uss78Open ↗

Elisa Francesca Roselli <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

The bike by the firm Giant that I was looking at over the weekend, as an upgrade for my current
cheap-and-cheerful first bike, had front and back lights that were powered by a hub dynamo.

In Cambridge over the summer on my rented bike, I had experience of a light powered by rim-dynamo
and absolutely _loathed_ it. It was not just unreliable, only going on when I was pedalling fast
and thus failing at critical intersections whenever I slowed down, but drained so much power from
the bike that I could scarcely manage it on pancake-flat Fenland terrain. I decided that I would
avoid dynamo lights forever and, on returning, had my home bike fitted with a very expensive and
bright front light powered with a heavy rechargeable battery pack.

But the salesman told me that this power-draining effect of the rim-dynamo did not apply to
dynamos powered from the hub. Can anyone comment or confirm?

First, a decent quality rim dynamo, properly set up, should give much better performance than what
you describe. It may be audible when running, but it shouldn't drain _that_ much power, to "scarcely
manage it on ... flat... terrain."

For comparison: When doing a fast tour a couple years ago, I was doing roughly 20 mph on long, flat
roads, for long distances. At one point, I accidentally bumped my dynamo and it was on without my
knowing it. At first I was puzzled by the funny noise my bike was making. Then I noticed my speed
had dropped a bit, roughly 1 mph. It took me a little while to put two and two together and shut the
dynamo off, but it showed me pretty conclusively that my dynamo wasn't slowing me a _lot_.

It's possible you had an old one whose bearings were very worn, and/or in dire need of lubrication.
It's also possible yours was not properly aligned with the tire, causing excessive "scrubbing" and
friction. Also, if the spring pressure holding the roller against the tire is excessive, this can
cause more drag.

The first cause seems most likely. The latter two will make some difference, but they'd have to be
extreme, indeed, to make things as bad as you describe.

Now: I like generators (dynamos) mostly because I find them to be the most convenient and reliable
way of getting decent light. I'll admit, though, that their installation takes more mechanical (and
electrical) know-how than a simple battery light. The alignment is one aspect of this. Proper
grounding is another, since most still use the frame as an electrical conductor, rather than the
proper double wiring I use.

These aspects should be far easier with a hub dynamo. There's nothing to align, and they come with
proper grounding wires. Furthermore, they are inherently more efficient, meaning more of your work
goes into producing light, as opposed to friction.

You should probably read the article at myra-simon.comdynotest.htmlOpen ↗ which compares
many different dynamo designs, and puts the energy losses into proper perspective - at least, on
properly installed dynamos.

BTW, mine is an old Soubitez bottom-bracket (or roller) type dynamo. It gives good light down to
about, oh, 5 miles per hour. Not as bright as full speed, but then it doesn't need to be as bright
as full speed. Good electrical connections, a good halogen bulb, and a headlight with good optics
are all important.

Once properly set up, you almost never need to think much about your dynamo. It just keeps on
producing light.

- Frank Krygowski

Steven Scharf said:

The bigger problem with dynamo systems is that the dynamo only generates 3 watts (there is one 6
watt dynamo available). In the U.S. anyway, a 3 watt lighting system is woefully inadequate.

Says who? The Schmidt dynohub + one or two headlights is standard issue among US randonneurs, who
put in serious night miles every year. That's pretty much the BMW of lighting systems and will cost
around $300 for a built wheel and lights. You can get a good 3W bottle-dynamo system for much less.
I've used both the Schmidt hub and the Lumotec 6 for a couple of years, and find them more than
adequate for riding either in the city or the countryside. The light from the Lumotec 6, combined
with one of the basic B & M front lights, does a better job of lighting the road than the basic
Niterider TrailRat 10W unit my wife used to use, before she tried out the generator system. The
Niterider unit cost around $100; the Lumotec + light, around $52. The TrailRat doesn't come with a
"smart" charger, so in addition to having to remember to charge it up regularly, you have to be
careful not to over- or under-charge it. You can get better featured rechargeable systems, but
they're much more expensive.

Hub-based lighting systems work even better than the bottle generator, create minimal drag, and are
basically fit and forget systems--perfect for utility bikes or, for that matter, for performance
riding outside of off-road conditions.

Trent

I have been using a SON-Schmidt hub dynamo (coupled to a B&M Oval front light + diode/capacitor rear
light) for a few months now, including a few hours riding in absolute dark on unknown roads, and I'm
very happy and impressed. I strongly recommend it if you intend to ride frequently at night.

I gave up "bottle" dynamos years ago, and in the meantime used an "external hub" dynamo called
FER-2002. It was actioned by a finger that you clicked into the spokes when you needed light. It was
more reliable than a bottle dynamo (no slippage on the tires when wet) but relatively noisy,
un-aesthetic, and much less powerful than the SON.

Jacques

"Luigi de Guzman" <[email hidden]> wrote in message

Quoted message said:

That said, when they were working, I never lacked lights when I needed them, which is more than I
can say for battery-lights.

Yes, with battery powered lights, you may need to carry a set of spares in your seat bag.

Quoted message said:

Unfortunately, since here in America nobody actually uses their bicycles, there are no
dynamo-driven lights to be found anywhere (except for extremely cheap dynamo sets--who buys
these?--at X*Mart).

When I was a kid in the US, *everybody* had dynamo-powered lights--battery powered lights were too
weak to be really useful. But now, I wouldn't trade my current battery powered lights for the old
'whine and drag' of the generator set.

Mark

James Thomson said:

Hub dynamos are heavier than bottle dynamos, and have a little drag even with the lights off, but
tend to be more reliable (especially in the wet), more efficient when in use, and aren't sensitive
to alignment as rim- or tyre-driven dynamos tend to be.

Would you recommend them over a light like the one I have, powered by a rechargeable battery?
Are they more reliable through being always powered, or less reliable through requiring that you
be moving?

Also, if you buy a bike with a hub dynamo and don't like it, can you remove it or is it a palaver?

Quoted message said:

There's a detailed article on dynamos here:

myra-simon.comdynotest.htmlOpen ↗

Thanks for the link, James. I will study it attentively.

Elisa Francesca Roselli Ile de France

Quoted message said:

Dynamo hubs still have an extra load; those 3-6 watts are being generated from somewhere, no
matter where the dynamo is located.

Of course, if there's a switch on the light, or you add one in, when the light isn't on, the drag
goes way down.

Peter

Quoted message said:

Hub dynamos are heavier than bottle dynamos, and have a little drag even with the lights off, but
tend to be more reliable (especially in the wet), more efficient when in use, and aren't sensitive
to alignment as rim- or tyre-driven dynamos tend to be.

I use mine to drive either one or a pair of headlights. I run a separate

This congrues with my experience. Three years ago I replaced my home-maid battery light
(outperforming the ones on sale) by a Schmidt dynohub with 2 headlights. Excellent results.
Nightrides are pure enjoyment now, 70kph in a descent at night is no problem anymore. Schmidt is a
highperformance model, the Shimano a middle-quality consumer one. The price differs likewise. Last
month, during the long-distance ride Paris-Brest-Paris, there were lot's of riders using Schmidt
hubs, quite some used Shimano hubs. Those riders relying on battery-powered systems were lot's
slower during the night, except when following Schmidt dynohub equipped riders.

Ivo

Steven Scharf said:

Dynamo hubs still have an extra load; those 3-6 watts are being generated from somewhere, no
matter where the dynamo is located.

That's true. But to give you an impression of the drag involved, for the first two years I ran my
Shimano NX30 dynohub, I did so with two 2.4W lamps in series permanently switched on, day and night.
The additional drag didn't merit the effort involved in wiring in a switch.

Quoted message said:

The bigger problem with dynamo systems is that the dynamo only generates 3 watts (there is one 6
watt dynamo available).

That's not so. Most dynamos put out roughly half an amp. In a hub dynamo, with a high impedance
relative to the load attached, the power output is determined mostly by the load you attach. Attach
a 0.5A/3W bulb, and you get 3 watts of power. Attach two in series, and the power output rises to
6W. The Dymotec S12 is nominally a 12V dynamo, so puts out one amp.

Quoted message said:

In the U.S. anyway, a 3 watt lighting system is woefully inadequate.

The USA is a large and varied place. EFR lives in France.

A 3W halogen bulb in a lamp with well-designed optics can put out a useful amount of light. Many
systems with higher nominal power outputs waste a lot of light with poorly-designed optics. To a
rough approximation, I'd say a 3W halogen bulb in my Lumotec headlamp compares well with my 10W HOT
Vistalite (MR11) bulb - which puts as much light up in the air as it does down on the road.

Quoted message said:

The reality is that you can buy a high power rechargeable system for far far less than a quality
dynamo system. A 6 watt dynamo system will cost well over $300.

Dymotec S12: $247 Headlight: $ 64 Taillight: $ 54

peterwhitecycles.comdymotec.aspOpen ↗

The system that EFR was asking about was included in the cost of a new bike. Even so, if you don't
make 12V a requirement, you can do much better than you suggest above. The following prices are from
roseversand.deroseversand.deOpen ↗

B&M Lumotec Plus (Standlicht) - 20 euros B&M Lumotec - 8.70 euros B&M DToplight Plus (Standlicht) -
20 euros Dynamos from 6 - 91 euros (Nexus NX30 - 36 euros)

My own system uses an NX30 (I was building a new front wheel anyway) with one each of the Lumotec
lamps, and an LED rear light that I already owned.

I own a Cateye Stadium 3 metal halide lamp and a selection of Vistalight heads and batteries. But
the system that gets the most use is my Nexus.

James Thomson

Elisa Francesca Roselli said:

Would you recommend them over a light like the one I have, powered by a rechargeable battery?
Are they more reliable through being always powered, or less reliable through requiring that you
be moving?

Batteries and dynamos have their own sets of pros and cons, but for a utility bike I prefer dynamo.
You can never forget to recharge a dynamo, and it remains permanently attached to the bike - an
advantage if you stay out later than expected. There's no risk of batteries running flat during a
long ride. Some dynamo headlamps (Lumotec 'Standlicht' models, for example) incorporate a capacitor
that powers an integrated LED light when the bike is stationary, and I sometimes carry a separate
white LED headlamp as an emergency light.

Quoted message said:

Also, if you buy a bike with a hub dynamo and don't like it, can you remove it or is it a palaver?

You would need a new front hub and spokes. The simplest thing to do would be to buy a new front
wheel and sell your dynamo wheel - which would probably leave you in profit.

James Thomson

Mark Weaver said:

"Luigi de Guzman" <[email hidden]> wrote in message

Quoted message said:

That said, when they were working, I never lacked lights when I needed them, which is more than I
can say for battery-lights.

Yes, with battery powered lights, you may need to carry a set of spares in your seat bag.

Quoted message said:

Unfortunately, since here in America nobody actually uses their bicycles, there are no
dynamo-driven lights to be found anywhere (except for extremely cheap dynamo sets--who buys
these?--at X*Mart).

When I was a kid in the US, *everybody* had dynamo-powered lights--battery powered lights were too
weak to be really useful. But now, I wouldn't trade my current battery powered lights for the old
'whine and drag' of the generator set.

New generators are mighty nifty and less bad. Also, I find that generator lights are a lot
brighter in practice than you might expect-- cycling in the fenland dark with dynamo lights was
quite good enough.

I seem to recall that the maximum allowable wattage for vehicle headlights was on the order of 45
watts, anyway--and that's for things that move considerably faster than my lardy [censored] on its way
home from the library.

-Luigi

Quoted message said:

Mark

In article <[email hidden]>, trent gregory hill

Quoted message said:

Quoted message said:

The bigger problem with dynamo systems is that the dynamo only generates 3 watts (there is one 6
watt dynamo available). In the U.S. anyway, a 3 watt lighting system is woefully inadequate.

Says who? The Schmidt dynohub + one or two headlights is standard issue among US randonneurs, who
put in serious night miles every year. That's pretty much the BMW of lighting systems and will cost
around $300 for a built wheel and lights. You can get a good 3W bottle-dynamo system for much less.

"Watts" isn't the right measure, anyway. That refers to input, not output (lumens). I have one of
these S6 generators and a Bisy light from peterwhitecycles.comdymotec.aspOpen ↗ The light is
much, much brighter than one of those 4-AA battery lights (which I often use with it for a "belt and
suspenders" approach.

The quality of the light is either a function of better optics in the Bisy light, or that the
electricity is so "fresh", having just been generated rather than sitting around in a battery on a
shelf for a while 😉