Any comments on the Supernova Infinity dynamo hub

SMS wrote:
On 9/28/2011 6:45 AM, Ralph Barone wrote:
I ran across this particular dyno hub
http://www.supernova-lights.com/en/products/infinity_8.html while
scouring the web for a dynamo hub (hey, Google search sometimes
works...). Does anybody have any experience with this manufacturer's
product?

I think the hub in the Tern model is this one:
http://www.sp-dynamo.com/spproductswitchdisc.html. Given Tern's desire
to move upscale in folders, and knowing Josh Hon, I'd be surprised if he
used any really crappy components on his new line. The specs for the
Tern model with the Shutter Precision dynamo hub are at
http://www.ternbicycles.com/bikes/eclipse-s11i?quicktabs_bike_tabs=2#quicktabs-bike_tabs.

It's too bad they don't give the efficiency specs. But from
http://www.sp-dynamo.com/spproductswitchdisc.html
it doesn't look like the output is very well regulated.

But looking at http://www.sp-dynamo.com/spproductlight.html, it's nice
to see that they've at least attempted to design a lamp that puts the
lumens where they're needed, instead of wasting them on the overhead
trees, as Scharf prefers!

Very good idea since the drag on those dynamo hubs when engaged, even
when the lights are off and the hub is not generating any power, is
significant.

"Significant"?? Here's some data:
http://www.bikequarterly.com/VBQgenerator.pdf
Some crappy dynohubs may have significant light-off drag, but most good
ones consume only about two Watts at 30 kph. That amount of drag would
slow a cyclist by only about 0.1 kph, as several online calculators will
show. That's not significant.


--
- Frank Krygowski

SMS wrote:
On 9/29/2011 7:42 AM, Lou Holtman wrote:
On 29 sep, 16:23, Clive wrote:
On 29/09/2011 10:07, SMS wrote:

Very good idea since the drag on those dynamo hubs when engaged, even
when the lights are off and the hub is not generating any power, is
significant.

That's just utter nonsense. The drag is insignificant, even when
generating.

Would I have a dynahub light system if there were significant drag
when generating?

Yes, because the alternative, up until now, has been unacceptable.

Would I leave my front wheel with dynahub on my bike during summer
season when there was significant drag when not generating?

Yes.

Hell no. I do have dynahub light systems and leave my front wheel on
my bike in summer season. So it is utter nonsense and the supernova
hub solves a non existing problem introducing more complexity and
inconvenience.

You don't realize just how much the extra drag actually is. What you
need to do is to compare a dynamo and a non-dynamo wheel, off the bike.

That's been done. It's shown you to be wrong. Yet again.

Think about it this way. A human can put out about 1/10 HP continuously
(around 75W).

You're underestimating rider power to help your argument. 75 Watts
yields about 20 kph, or about 13 mph, on a typical road bike on the
flats with no wind. I'm well over 60 years old and I cruise at 18 mph.

If you're using 3W lights, you're expending about 6W of energy into
running the lights. With the lights off, the energy expended goes down,
the SON required around 5.4W of input with lights off, and around 5.6W
of input power with lights on (for 3W lights). The Shimano Alfine was
slightly worse. See
http://www.ecovelo.info/2009/11/05/new-dyno-hub-test/.

That test was not done very well, as indicated by the comments. Using a
Powertap on a bike on rollers to measure front hub resistance, as they
did, is far less accurate than simply measuring the front hub resistance
directly, as done in these tests:
http://www.myra-simon.com/bike/dynotest.html
http://www.bikequarterly.com/VBQgenerator.pdf
http://www.nabendynamo.de/service/pdf/ar_01-02_2009.pdf

Direct measurement shows roughly 2 Watts drag at 30 kph for a SON hub
and not much more for the better Shimano hubs. Again, that drag is
worth only about 0.1 kph for a 30 kph rider.

--
- Frank Krygowski

On Sep 29, 10:06 am, Frank Krygowski
wrote:
SMS wrote:
On 9/29/2011 7:42 AM, Lou Holtman wrote:
On 29 sep, 16:23, Clive wrote:
On 29/09/2011 10:07, SMS wrote:

Very good idea since the drag on those dynamo hubs when engaged, even
when the lights are off and the hub is not generating any power, is
significant.

That's just utter nonsense. The drag is insignificant, even when
generating.

Would I have a dynahub light system if there were significant drag
when generating?

Yes, because the alternative, up until now, has been unacceptable.

Would I leave my front wheel with dynahub on my bike during summer
season when there was significant drag when not generating?

Yes.

Hell no. I do have dynahub light systems and leave my front wheel on
my bike in summer season. So it is utter nonsense and the supernova
hub solves a non existing problem introducing more complexity and
inconvenience.

You don't realize just how much the extra drag actually is. What you
need to do is to compare a dynamo and a non-dynamo wheel, off the bike.

That's been done. It's shown you to be wrong. Yet again.

Think about it this way. A human can put out about 1/10 HP continuously
(around 75W).

You're underestimating rider power to help your argument. 75 Watts
yields about 20 kph, or about 13 mph, on a typical road bike on the
flats with no wind. I'm well over 60 years old and I cruise at 18 mph.

If you're using 3W lights, you're expending about 6W of energy into
running the lights. With the lights off, the energy expended goes down,
the SON required around 5.4W of input with lights off, and around 5.6W
of input power with lights on (for 3W lights). The Shimano Alfine was
slightly worse. See
http://www.ecovelo.info/2009/11/05/new-dyno-hub-test/.

That test was not done very well, as indicated by the comments. Using a
Powertap on a bike on rollers to measure front hub resistance, as they
did, is far less accurate than simply measuring the front hub resistance
directly, as done in these tests:http://www.myra-simon.com/bike/dynot...01-02_2009.pdf

Direct measurement shows roughly 2 Watts drag at 30 kph for a SON hub
and not much more for the better Shimano hubs. Again, that drag is
worth only about 0.1 kph for a 30 kph rider.


It *is* work, though, and drag on a bicycle is, well - a drag.

On 9/28/2011 12:47 PM, Jay Beattie wrote:

I know it is sold through Velo Orange -- for less than a SON, but I
don't know where else it is sold. -- Jay Beattie.

It's mainly sold to manufacturers of higher-end commute and touring
bicycles.

On 9/29/2011 10:25 AM, Dan O wrote:

snip

It *is* work, though, and drag on a bicycle is, well - a drag.

Also, be very careful about the source of drag measurements. Take data
from a hub manufacturer with many grains of salt.

The tests reported by Ecovelo were very straightforward. Using the same
tube and tire they measured the power input with lights on and off. They
were only measuring drag.

That said, when testing on rollers you're not including the most
significant "drag" which is wind resistance. So the drag of the hub at
12 or 18 mph is not going to be very noticeable compared to wind drag.

This isn't so different than tire driven dynamos where the drag is very
noticeable at low speeds, not so noticeable at higher speeds. It's
always amusing to see claims of "I don't notice the drag when the lights
are off." Of course not, you have nothing to compare it against! The
only way to measure drag is to actually measure it.

It's amazing to see that there's even any argument about this. Does
anyone believe that the output from a hub dynamo does not require any
input? Has anyone ever spun a wheel with a dynamo hub with the lights
off? As a percentage of human output power the drag losses are not huge,
nor are they insignificant.

As an aside, early this morning I agreed to be interviewed by a research
company that was doing follow-ups on Interbike (disclosu there was an
honorarium). One question they asked was to compare innovation in
bicycle products from Taiwan, Germany, and the U.S.. I immediately
thought of dynamo hubs and lighting and replied that the German
components were usually very well engineered and of higher quality
construction, but were very expensive and there was little innovation,
while the Taiwanese tended to be more innovative and produced components
that were of sufficiently high quality at prices where they could be
sold in large quantities. I couldn't think of U.S. products to compare
at the time, though in retrospect I guess I could have used Greenfield
kickstands and Wald racks and baskets.

Since we're on the subject of dynamos and lighting, this may be a good
time to mention the instructional web site I put up at
http://nordicgroup.us/s78/mr16LED.htm which describes how to use an
MR16 LED lamp with a dynamo. The MR16 lamps have an integrated bridge
rectifier and work directly with an unregulated AC bicycle dynamo. Even
though they are rated at 12V, they work fine with a 6V dynamo (which
typically puts out more than 6V). These lamps have a beam pattern equal
to, or superior to most bicycle lights, and are very inexpensive. I have
added some of the recently released dynamos.

Aside from those opposed to the laws of physics and thermodynamics on
moral grounds, it's still very good to see that there appears to be at
least a small resurgence of interest in dynamo lighting.

Op 29-9-2011 18:22, SMS schreef:
On 9/29/2011 7:42 AM, Lou Holtman wrote:


Think about it this way. A human can put out about 1/10 HP continuously
(around 75W).

75 Watt. I hope I can output more. Did it easy this evening after the
clubride yesterday. Still averaged 27 km/hr, almost no wind, on the
hoods and tires with not the best rolling resistance rating. Carl how
much power did I put on the cranks?

A dynamo is rated at 3W and actually can put out about 6W.

If you're using 3W lights, you're expending about 6W of energy into
running the lights.

3 Watts with a efficiency of 65-70%
With the lights off, the energy expended goes down,
the SON required around 5.4W of input with lights off,

Specs of my hub says 0.4W at 15 km/hr and 28"wheels.
http://www.nabendynamo.de/produkte/SONdelux.html
Lets triple that a you have 1-2 Watts
5.6 Watt? No way.


So the question is whether or not "saving" 5W of power in the daytime is
worth the extra complexity of a hub dynamo that can disengage the dynamo
when not in use.


It is not 5.6 Watt.

Lou

SMS wrote:
On 9/29/2011 10:25 AM, Dan O wrote:

snip

It *is* work, though, and drag on a bicycle is, well - a drag.

Also, be very careful about the source of drag measurements. Take data
from a hub manufacturer with many grains of salt.

If the tests are done with other observers (such as with the technical
editor of the British CTC's magazine), are properly designed, and are
quite repeatable, there's good reason to believe they are reasonably
accurate.

The tests reported by Ecovelo were very straightforward. Using the same
tube and tire they measured the power input with lights on and off. They
were only measuring drag.

If I understand them correctly, they mounted a dynohub in a bike with a
power meter, put the bike on rollers, pedaled at various rpms, and
measured TOTAL power input. They then changed front hubs and repeated,
with the inclusion of a plain (non-dynamo) front hub. Then they
subtracted power readings to find the drag of each dynohub.

The problem here is measuring a large quantity (total input power) and
subtracting values in hopes of detecting small differences in that large
value. It's simply bad measurement technique. It should not be
expected to be as accurate as measuring the drag more directly.

The other test method used was much more direct. A wheel with attached
flywheel was fitted with data acquisition equipment that recorded the
deceleration under generator plus friction plus aero drag. You're
dealing with far smaller confounding factors, and they're easier to
account for.

It's
always amusing to see claims of "I don't notice the drag when the lights
are off." Of course not, you have nothing to compare it against!

Um... What about our other bikes, that do not have hub dynamos? Why
should those not be used for comparison?

Does
anyone believe that the output from a hub dynamo does not require any
input?

Nobody has claimed that. We're just tired of you exaggerating the
amount of input power to the dynamo. Re-read the portion of
http://www.myra-simon.com/bike/dynotest.html that leads to the statement
"If that's a hill I'm a Dutchman!"

Has anyone ever spun a wheel with a dynamo hub with the lights
off?

Of course. That's why we're disputing your claims.

Aside from those opposed to the laws of physics and thermodynamics on
moral grounds, it's still very good to see that there appears to be at
least a small resurgence of interest in dynamo lighting.

:-) This from the guy who spent years on this discussion group,
claiming at every opportunity that generators were no good!


--
- Frank Krygowski

On Sep 29, 9:38*am, Frank Krygowski
wrote:
SMS wrote:
On 9/28/2011 6:45 AM, Ralph Barone wrote:
I ran across this particular dyno hub
http://www.supernova-lights.com/en/products/infinity_8.html while
scouring the web for a dynamo hub (hey, Google search sometimes
works...). Does anybody have any experience with this manufacturer's
product?

I think the hub in the Tern model is this one:
http://www.sp-dynamo.com/spproductswitchdisc.html. Given Tern's desire
to move upscale in folders, and knowing Josh Hon, I'd be surprised if he
used any really crappy components on his new line. The specs for the
Tern model with the Shutter Precision dynamo hub are at
http://www.ternbicycles.com/bikes/eclipse-s11i?quicktabs_bike_tabs=2#....

It's too bad they don't give the efficiency specs. *But fromhttp://www.sp-dynamo.com/spproductswitchdisc.html
it doesn't look like the output is very well regulated.

But looking athttp://www.sp-dynamo.com/spproductlight.html, it's nice
to see that they've at least attempted to design a lamp that puts the
lumens where they're needed, instead of wasting them on the overhead
trees, as Scharf prefers!

Very good idea since the drag on those dynamo hubs when engaged, even
when the lights are off and the hub is not generating any power, is
significant.

"Significant"?? *Here's some data:http://www.bikequarterly.com/VBQgenerator.pdf
Some crappy dynohubs may have significant light-off drag, but most good
ones consume only about two Watts at 30 kph. *That amount of drag would
slow a cyclist by only about 0.1 kph, as several online calculators will
show. *That's not significant.

I like some light spew when I'm riding through the cemetery at night.
http://www.flickr.com/photos/31019817@N02/5845427153/ It's dark and
scary! http://www.flickr.com/photos/12792160@N00/18304701/

-- Jay Beattie.

On 9/29/2011 12:48 PM, Jay Beattie wrote:

I like some light spew when I'm riding through the cemetery at night.
http://www.flickr.com/photos/31019817@N02/5845427153/ It's dark and
scary! http://www.flickr.com/photos/12792160@N00/18304701/

Great photo.

Spew is good in a bicycle light. You do not want a tightly focused beam
that illuminates only the pavement directly in front of you. That type
of light is okay at very low speeds with no traffic, but in real life,
at least outside the Netherlands, you want to illuminate off to the
sides a little, and further ahead than some of the old incandescent
dynamo powered lights can reach.

Those old lights did not tightly focus their beam just for the heck of
it, they needed to make a compromise based on the limited power available.

I'm not sure how the original poster's question on the switchable
Supernova hub became a debate over spew! This hub has already won
multiple awards for its design.

If I didn't know any better I'd say that some Son owners are a bit upset
about the Supernova Infinity 8, which is rather silly.

Clive George wrote:
On 29/09/2011 10:07, SMS wrote:

Very good idea since the drag on those dynamo hubs when engaged, even
when the lights are off and the hub is not generating any power, is
significant.

That's just utter nonsense. The drag is insignificant, even when
generating.

Saying "yes it is" and "no it isn't" is not an argument.

I want data!

--
JS.