Any comments on the Supernova Infinity dynamo hub

On Oct 4, 8:06 pm, Frank Krygowski wrote:
On Oct 4, 8:28 pm, James wrote:

SMS wrote:
On 10/4/2011 8:38 AM, Dan O wrote:

Yeah, and with a relatively fixed mount headlamp, you can't as readily
bring the light to the work.

There's that, but I suspect that most commuters with a fixed headlamp,
whether battery powered or dynamo powered, also carry along a flashlight
in case they need to do repairs.

Doubtful, unless the commuter regularly travels completely unlit streets.

I do carry a tiny LED coin-cell flashlight for such events, but
(usually) only with my utility bike, the one I ride most at night.

Still, last nighttime flat I fixed (this spring) I had to do it under
a streetlight. The flashlight's battery was dead. It must have
accidentally turned on and drained its battery in my handlebar bag. :-
(


In the earliest days of my current commuting career, I walked about
half a mile to a lighted driveway in order to fix a flat. Yes, I know
people will say I was nuts to be riding in the dark without a light,
but that part I could handle (though I really appreciate having a
bright headlight now that I do). People think I'm nuts for riding at
all, though.

On 10/4/2011 6:52 PM, James wrote:
SMS wrote:
On 10/4/2011 5:28 PM, James wrote:

As a motorist, I don't recall not being able to see the whole of an
intersection on streetlights alone. I cannot recall a situation as you
describe.

It has nothing to do with the motorist being able to see the whole of
an intersection. When you have a bright light from a bicycle (or
vehicle) shining at you at night, you don't turn in front of it--it
registers on your brain that there is something there.

I don't look only at lights.

You're a cyclist, you are more aware of things while driving.

Ideally, a dynamo powered light with a standlight would be able to be
set to a strobe mode when the bicycle isn't moving.

Why not sell a blinky with a dynamo recharge hole then?

Because there is no market for it. A blinky's batteries last so long
that adding all that extra circuitry, and using rechargeable batteries,
would make it too expensive for the mass market.

You have to look at the big picture here, very few casual cyclists are
going to spend $50 on lights, let alone $500 for a new SON dynamo high
end wheel and LED dynamo lights, or even $150 for a low end wheel with a
Shimano or other cheaper dynamo.

On 10/4/2011 6:49 PM, James wrote:

I don't come across too many folks riding at night that don't have at
least some lights on their bike. Kids on BMX are more likely on the back
streets with no lights, than commuters on the main roads.

I'm sure that it varies considerably by city and by neighborhood, but
certainly in middle class neighborhoods there are definitely fewer unlit
cyclists than in the past.

It's probably due to the wider availability of LED bicycle lights, LED
flashlights, and bike mounts for flashlights. You can walk into Fry's
Electronics, many drug stores, Target, Walmart, or many dollar stores
and come out with something halfway decent for a very low price. Daiso,
the Japanese $1.50 store which is all over Japan and Taiwan, and which
has a few outlets on the U.S. west coast have carried nurse locks (those
ring locks that mount to the bike), all sorts of lights, umbrella
holders, covers, tools, locks, patch kits, bottle cages, and
inexplicably, repair kits for Woods valves. They also have a wide
variety of stainless metric Allen head bolts.

SMS writes:

On 10/4/2011 11:48 AM, Radey Shouman wrote:
writes:

Your average young person conflates 'reflector' and 'light' and uses
the words interchangeably, to our consternation here in the bike shop.

About this time last fall, while cutting though a parking lot around
dusk, I was flagged down by a young lady of perhaps five, on her own
bicycle. She wanted me to show her how to turn her light on. Sadly, I
had to tell her it was only a reflector.

She was entranced by my light -- has to be an underserved market in
there somewhere.

I thought that AMuzi's "young person" reference was to at least school
age children. It's entirely understandable that a five year old would
not know that a reflector and a light are different.

It may not be the case everywhere, but personally I've noticed fewer
unlit cyclists in my area. Even at the high school, where kids often
go to school in the pre-dawn hours and may come home late after
extra-curricular activities, they usually have lights (though I'm
pretty sure that the number of bicycles with hub dynamos at my kids
high school equals two, and both of those bicycles come from my house!

Last night I did see two kids on BMXen, probably high school aged, with
lights. In my experience that's pretty rare, but perhaps becoming less
so.

You don't see many five year old's riding their bikes at night, with
or without lights.

I don't think this one was allowed outside the parking lot.

--

In article ,
James wrote:

Radey Shouman wrote:

When one spins a dynamo wheel by hand it seems bad: very notchy, and
spins down much quicker than a normal wheel. My contention is that one
tends to overestimate the (certainly nonzero) energy cost of turning the
dynamo with the light off. With the light on the wheel spins down
quicker than with the light off, but the resistance feels smoother.

You are likely correct.

People all too often overestimate the power consumed by bearings using
simple coast down tests on a wheel, for example. For the hub dynamo I'd
guess the same.

For a modern light wheel, there simply isn't very much inertia and
potential energy once spinning, to be lost to bearings or a dynamo, so
any fraction of a watt difference is very noticeable in the coast down
test, but not on the road while riding.

Once you get a bit of speed on the wheel
the aerodynamic drag is significant.
Furthermore, I think that aerodynamic drag
needs to be accounted for at low speed
as well to get an accurate number for
bearing and dynamo drag.

--
Michael Press

On 10/5/2011 12:05 PM, Michael Press wrote:

Once you get a bit of speed on the wheel
the aerodynamic drag is significant.
Furthermore, I think that aerodynamic drag
needs to be accounted for at low speed
as well to get an accurate number for
bearing and dynamo drag.

You'd think that aerodynamic drag is so significant that other sources
of drag are lost in the noise. But I'm reminded of GM getting approval
to do EPA mileage testing with the daytime running lights disconnected.
Why? Because of the extra load on the engine from the alternator being
loaded down more. You'd think the additional load would be so small in
the scheme of things, maybe an extra 60 watts, that it would not matter,
but apparently it did.

On 6/10/2011 6:05 AM, Michael Press wrote:
In ,
wrote:

Radey Shouman wrote:

When one spins a dynamo wheel by hand it seems bad: very notchy, and
spins down much quicker than a normal wheel. My contention is that one
tends to overestimate the (certainly nonzero) energy cost of turning the
dynamo with the light off. With the light on the wheel spins down
quicker than with the light off, but the resistance feels smoother.

You are likely correct.

People all too often overestimate the power consumed by bearings using
simple coast down tests on a wheel, for example. For the hub dynamo I'd
guess the same.

For a modern light wheel, there simply isn't very much inertia and
potential energy once spinning, to be lost to bearings or a dynamo, so
any fraction of a watt difference is very noticeable in the coast down
test, but not on the road while riding.

Once you get a bit of speed on the wheel
the aerodynamic drag is significant.

Certainly.

Furthermore, I think that aerodynamic drag
needs to be accounted for at low speed
as well to get an accurate number for
bearing and dynamo drag.


Yes, if you want accurate numbers.

For some folks I know, they take a wheel, spin it and see how long it
takes to spin down. Then change the bearings and try again, noticing
the difference in time for the wheel to spin down.

It is not a quest for friction values or wattage numbers, just a
comparative test.

If it took 45 seconds before, and 75 seconds after bearing adjustment or
replacement or cleaning and lubricating, then that is an appreciable
improvement - in their eyes. The actual difference in drag is tiny in
reality.

--
JS

On Wednesday, September 28, 2011 8:45:28 AM UTC-5, 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 manage a bicycle shop and have seen a lot of different dynamo designs. I wound up purchasing the infinity s from the same company after much research. I LOVE IT , extremely high power output , light weight , and rolls extremely smooth. I actually wound up filling a water bottle with a bunch of voltage modules and capacitors to charge my USB lights and camping power supply as i ride as well as do a few other more crazy things but if your not big into wiring electronics supernova offers a plethora of lights and other accessories that work well with their hub design and are plug n play. one thing to keep in mind if you ARE planning on wiring up your own modules is that this hub pushes close to 30 volts ac when up to speed so choose your rectifier/regulator modules accordingly. All in all an amazing hub though definitely recommend