Dynohub drag

On 10/20/2014 11:57 PM, jbeattie wrote:
On Monday, October 20, 2014 7:16:42 PM UTC-7, Frank Krygowski wrote:
On 10/20/2014 10:31 AM, jbeattie wrote:





What I'm getting at is that with a dyno light, you have an inherently hobbled light.

If it is StVZO compliant, it is purposefully hobbled in terms of its

output.



Not so. AFAIK, StVZO does not limit the number of lumens (i.e.

"output"). It imposes minimums for road illumination, not maximums.

It "hobbles" only in the same way that car headlights are "hobbled," to

not harm others. And in the process, it uses the lamp's output very

efficiently. That's a good thing.



Even if it is not StVZO compliant, it is hobbled by its limited input

voltage.



Also wrong. Sorry, Jay. The limitation on a typical dynamo is output

current, since they naturally (by design) put out a little over half an

amp, pretty much constant current. Voltage rises to match the load. If

there were enough benefit to running a standard dynamo at higher

voltage, it would be done by lamp manufacturers. Typical high output

LEDs need less than four volts anyway.

Yes, if you want to wire up lights in series, you can do that. But, I believe
StVZO limits a single light to 2.4 watts -- just because. And if you
wire a bunch
of lights in series, be content riding in the dark when your speed
drops. But, hey,
you don't need light when your riding slowly.

I don't recall whether StVZO limits to 2.4 watts. Phil gave us the
regulation text, but I don't have time to search it now. But IIRC your
main problem isn't related to higher total power, which is what the very
few address when they put good LED lamps in series. IIRC, your problem
is low speed lighting. Sorry, but we didn't know that ahead of time, or
we'd have been able to discuss it.

IIRC, StVZO _does_ specify minimum dynamo output at low speed, and I
think it's lamp specs specify minimum light output at low speed. But
I'm going by dim recollection. If I'm right, it might have saved you a
heap of trouble. (But maybe not, of course. You and Jeorg apparently
have super-unusual riding - or pushing your bikes - conditions.)

Back in my experiment-with-halogen-lamp days, I sometimes had two in
series. It was set up so I could use either lamp (to compare different
lamps) or both, selected by a simple handlebar switch. If you really
wanted to put lamps in series, we could tell you how to preserve low
speed lighting. But again, that's not your real problem, is it?

So, you have to agonize over reflectors, beam shapes, etc. because you have

to squeeze as much performance as possible out of a hobbled light.



Well, in the same sense that people who buy tires have to agonize over

longevity vs. rolling resistance vs. traction, etc. All equipment

decisions are compromises.

Right, and if a tire has no wet grip, it is a bad tire. It shouldn't be on the market.

Um... can we apply that philosophy to things like tiny LED lights or
Chinese flashlights?

Despite the unbounded evils of government regulation, I think there are
many times that standards are good. "Caveat emptor" is fine until
you're the buyer who should have known a lot more.

...yet with dyno lights, they can suck, and it's O.K. because
they're special! And quirky!

You really should try to understand that they _don't_ suck for those of
us who are praising them! I use them because they are better for me. I
used to use battery lights, but my bad experiences with them got me into
dynamos. I tried going back to battery lights, but they just didn't cut it.

Sure, I wouldn't want a dynamo light for, say, hauling my bike up a
cliff face as I climbed hand-over-hand. If that's close to what you're
doing, you probably should have said so!


I'll remind you that a survey of Paris-Brest-Paris riders a few years

ago found that dynamo light users were much more satisfied with their

lights than were battery light users. That doesn't match the idea of

"hobbled." And that was before dynamos did LEDs. If anything that

preference has probably gotten stronger.

I'll remind you that my commute is not 600 miles. I'll remind you that most
24 hour mountain bike racers use battery lights. I'll remind you that
virtually
every cyclist I see every night (which is a lot of cyclists) use little 120
gram bar lights that produce plenty of light -- more than most dynos and
with
zero complexity.

That's fine. The P-B-P reference was to counter your implication that
dynamos are flat-out inferior.

Tell you what: I may be willing to buy your SP hub. I'll expect some
discount, of course, but you'll recoup most of the cost. (I'm not
interested in the headlamp, for many reasons, but you can sell it to
someone, I'm sure.) You can go back to a 120 gram light on your handlebar.


Again, I'm sorry you got something that didn't match you unusual needs.

But your complaints apply to very few people; most of us don't go

walking our bikes up super-dark steep trails in the rain! If you'd

discussed that need here beforehand, you might have gotten some useful

advice.



As it was, the advice I gave was to arrange to try one out. I think it

would have been a useful move. In fact, I still think it would be a

useful move.



You're f****** nuts. NO store would give me a light to try, and only one
had a display with a wheel and dyno where you could switch between the
lights.
Otherwise, it was little lights on peg-boards or in cabinets with shiny new
wire-ends that the stores intended to keep shiny. What am I supposed to do?
Go door to door asking for a dyno light?

Wow. My town has nowhere near the commuter bike count of Portland, but
I can find other folks who use dyno lights, and ask them to take a ride
with me. Heck, I once had a bike shop contact _me_ to ask me to try out
a certain dynamo. And I'd be comfortable posting a request in our bike
club's newsletter, or to its website. I'm astonished that all those
things are impossible in Portland.

Too bad. I thought things were better there.


--
- Frank Krygowski

On Monday, October 20, 2014 7:07:40 PM UTC-7, James wrote:
On 21/10/14 12:28, jbeattie wrote:

On Monday, October 20, 2014 3:25:07 PM UTC-7, James wrote:

On 21/10/14 01:31, jbeattie wrote:











What I'm getting at is that with a dyno light, you have an

inherently



hobbled light.







Especially now with LEDs, I disagree.







If it is StVZO compliant, it is purposefully hobbled



in terms of its output.







Not at all. It's only "hobbled" in terms of how much light is

allowed



to reach other road users eyes. IIRC, there's no limit on how

much



light hits the road.







Mine for example, produces 80lux at 10m as the horizontal straight

ahead



intensity.



What light are you using again?



http://www.xxcycle.com/busch-and-mul...ndi-04,,en.php



I'm not wanting to wire multiple

headlights that flicker on climbs or fire-up after I'm off the stop.

I've already got 3 LEDs that fire up at different speeds.





I have one head light and one tail light.



For twisting descents at night, a flood light would be nice, but it's

not difficult to slow a bit so the bike doesn't lean as much. That is

about the only down side for me. I would add a second headlight for

high beam mode, wired in series and with a bypass switch, if I did that

sort of riding frequently.



Whatever you may think of battery lights, I could strap my battery

light back on the bike and ride for 11 hours with a reasonably well

shaped 300 lumen beam -- not StVZO but not a Chinese flashlight

either.



That's nice. I fill a water bottle or two, get on my bike and ride.



The only battery I have to think about is in my Garmin - which would be

a real nuisance if I didn't want to download the data anyway.



Do you have a powered hub next to your bike and an octopus of cables

ready to plug everything in at the end of a ride?


No. Currently, I don't even have a cyclometer on any of my bikes. Virtually all of my night riding is on my commuter bike -- even elective rides through the hills. After daylight savings time ends, the wet weather comes, the leaves fall, and I switch to 35mm-ish tires (often just 28s) with a little tread pattern. My commuter is a CX bike, and it becomes my do-it-all except for fast weekend rides in the daylight. Then I use my secret weapon! My CAAD 9 rain bike -- or if it's dry, my superfine SuperSix. After grinding around on my commuter all week with my light on all the time, riding the SuperSix this weekend was like being on an eBike.

When I was using a battery light, I recharged it daily or every other day -- mostly out of an abundance of caution. The L&M has a very lightweight battery pack that I strapped to my stem -- which was a little kludgy. I also have a NiteRider Pro750 with a bad switch (repairs underway) that had a strap-to-the-frame (no taking up the bottle cage) slide-in battery carrier that was much more convenient. The smaller, strap-on battery packs are actually less convenient for quick changes, IMO.

-- Jay Beattie.

On Tuesday, October 21, 2014 8:52:05 AM UTC-7, Frank Krygowski wrote:
On 10/20/2014 11:57 PM, jbeattie wrote:

snip

Back in my experiment-with-halogen-lamp days, I sometimes had two in

series. It was set up so I could use either lamp (to compare different

lamps) or both, selected by a simple handlebar switch. If you really

wanted to put lamps in series, we could tell you how to preserve low

speed lighting. But again, that's not your real problem, is it?



So, you have to agonize over reflectors, beam shapes, etc. because you have



to squeeze as much performance as possible out of a hobbled light.







Well, in the same sense that people who buy tires have to agonize over



longevity vs. rolling resistance vs. traction, etc. All equipment



decisions are compromises.



Right, and if a tire has no wet grip, it is a bad tire. It shouldn't be on the market.



Um... can we apply that philosophy to things like tiny LED lights or

Chinese flashlights?



Despite the unbounded evils of government regulation, I think there are

many times that standards are good. "Caveat emptor" is fine until

you're the buyer who should have known a lot more.



...yet with dyno lights, they can suck, and it's O.K. because

they're special! And quirky!



You really should try to understand that they _don't_ suck for those of

us who are praising them! I use them because they are better for me. I

used to use battery lights, but my bad experiences with them got me into

dynamos. I tried going back to battery lights, but they just didn't cut it.



Sure, I wouldn't want a dynamo light for, say, hauling my bike up a

cliff face as I climbed hand-over-hand. If that's close to what you're

doing, you probably should have said so!

Frank, anyone who does not share your riding style or experience has "unusual needs." I'm not hauling my bike up a cliff face. I'm walking up 65 widely spaced stairs on a trail. It's only 100 yards long, but its no fun in the dark. Portland is full of trails between paved roads, and I ride them frequently. I'm not just cruising through my village, waiving at all my friends standing behind their white picket fences. Climbing is also something most people living on the West Coast do by necessity -- including everyone living on the close-in westside of Portland. Good low speed light output is not an unusual need. Screen shots of beam patterns tell you nothing about low speed performance, unless there are serial beam shots at progressively higher speeds. Maybe you could direct me to that page.

I'm keeping my dyno hub and will try another light when I get the money or if I get too miserable. And I still want to see how my SuperNova performs in very dark, wet weather.

Oh, by the way, I encountered one other bike with a dyno in the rack today (Shimano hub, a Lumotec light) -- which brought the total number of dyno-equipped bikes to two. I couldn't quite figure out the other bike because it was an '80s Centurion Ironman with plastic platform pedals, a rack -- but I don't think it had fenders, which are required starting this week. Some odd choices being made.

-- Jay Beattie.

On 10/21/2014 9:32 AM, jbeattie wrote:

Frank, anyone who does not share your riding style or experience has "unusual needs." I'm not hauling my bike up a cliff face. I'm walking up 65 widely spaced stairs on a trail. It's only 100 yards long, but its no fun in the dark. Portland is full of trails between paved roads, and I ride them frequently. I'm not just cruising through my village, waiving at all my friends standing behind their white picket fences. Climbing is also something most people living on the West Coast do by necessity -- including everyone living on the close-in westside of Portland. Good low speed light output is not an unusual need. Screen shots of beam patterns tell you nothing about low speed performance, unless there are serial beam shots at progressively higher speeds. Maybe you could direct me to that page.

I'm keeping my dyno hub and will try another light when I get the money or if I get too miserable. And I still want to see how my SuperNova performs in very dark, wet weather.

Oh, by the way, I encountered one other bike with a dyno in the rack today (Shimano hub, a Lumotec light) -- which brought the total number of dyno-equipped bikes to two. I couldn't quite figure out the other bike because it was an '80s Centurion Ironman with plastic platform pedals, a rack -- but I don't think it had fenders, which are required starting this week. Some odd choices being made.

Clearly you need to leave Portland. You are living in the wrong place so
you have unusual needs. In fact nearly all of us need to leave where we
are living and move to the mythical kingdom where 100 lumen dynamo
lighting is all that is ever required.

Once my son graduates from high school we can sell our multi-million
dollar palace to some Apple employee and take the money and move to
Appalachia. As long as they have Kaiser.

On 10/21/2014 9:49 AM, Bertrand wrote:


I'm just curious whether there are any physiological or mechanical reasons
why it would be more efficient or better to spin slower on a steep hill
than
on the flat at the same power. I suspect that there aren't, and that any
preference for lower climbing cadence is based mostly on equipment
limitations, habit, and a macho tradition that sees triples, compacts, or
giant cassettes as unmanly.

Speaking for myself: I have triple cranks on most of my bikes. My
policy is to avoid using the granny chainring unless I'm on an overnight
tour, or riding the tandem. It's not a macho thing; my objective is to
build muscle.

As soon as I put packs on the bike and set off to travel somewhere, I
drop down into a low gear at every opportunity. My objective then is to
make it as easy as possible for the muscle I've been able to build.


On the flats, experienced riders seem to prefer higher cadence when
going at
higher power. For example, puttering along at 10 mph with my
sister-in-law,
I'm probably down around 60 rpm. On a hard group ride, it will be around
90. When Jens Voigt set the hour record recently, I think his average
cadence was about 103. And sprinters at top speed seem to prefer around
120
rpm, deliberately choosing a lower gear when needed to keep that high
cadence.

It always seemed to me that the benefits of reasonably high cadence are
obvious, if one wants to bike any distance. Muscles fatigue much
sooner, in terms of work accomplished, if they're heavily loaded.

But I suspect that one has to learn the rapid coordination of the
related muscles to crank along at 90+ rpm. Racers probably learn that
coordination much better than anyone else, so they reap benefits at
cadences where we might not.


--
- Frank Krygowski

On Monday, October 20, 2014 10:07:40 PM UTC-4, James wrote:
On 21/10/14 12:28, jbeattie wrote:

On Monday, October 20, 2014 3:25:07 PM UTC-7, James wrote:

On 21/10/14 01:31, jbeattie wrote:











What I'm getting at is that with a dyno light, you have an

inherently



hobbled light.







Especially now with LEDs, I disagree.







If it is StVZO compliant, it is purposefully hobbled



in terms of its output.







Not at all. It's only "hobbled" in terms of how much light is

allowed



to reach other road users eyes. IIRC, there's no limit on how

much



light hits the road.







Mine for example, produces 80lux at 10m as the horizontal straight

ahead



intensity.



What light are you using again?



http://www.xxcycle.com/busch-and-mul...ndi-04,,en.php



I'm not wanting to wire multiple

headlights that flicker on climbs or fire-up after I'm off the stop.

I've already got 3 LEDs that fire up at different speeds.





I have one head light and one tail light.



For twisting descents at night, a flood light would be nice, but it's

not difficult to slow a bit so the bike doesn't lean as much. That is

about the only down side for me. I would add a second headlight for

high beam mode, wired in series and with a bypass switch, if I did that

sort of riding frequently.



Whatever you may think of battery lights, I could strap my battery

light back on the bike and ride for 11 hours with a reasonably well

shaped 300 lumen beam -- not StVZO but not a Chinese flashlight

either.



That's nice. I fill a water bottle or two, get on my bike and ride.



The only battery I have to think about is in my Garmin - which would be

a real nuisance if I didn't want to download the data anyway.



Do you have a powered hub next to your bike and an octopus of cables

ready to plug everything in at the end of a ride?



--

JS

USE A BATT LIGHT MOUNTED LOW ON FORK

On 10/21/2014 12:32 PM, jbeattie wrote:
On Tuesday, October 21, 2014 8:52:05 AM UTC-7, Frank Krygowski wrote:
On 10/20/2014 11:57 PM, jbeattie wrote:

...yet with dyno lights, they can suck, and it's O.K. because
they're special! And quirky!

You really should try to understand that they _don't_ suck for those of
us who are praising them! I use them because they are better for me. I
used to use battery lights, but my bad experiences with them got me into
dynamos. I tried going back to battery lights, but they just didn't cut it.

Sure, I wouldn't want a dynamo light for, say, hauling my bike up a
cliff face as I climbed hand-over-hand. If that's close to what you're
doing, you probably should have said so!

Frank, anyone who does not share your riding style or experience has
"unusual needs." I'm not hauling my bike up a cliff face. I'm walking up
65 widely spaced stairs on a trail. It's only 100 yards long, but its no
fun in the dark. Portland is full of trails between paved roads, and I
ride
them frequently.

Walking a commuting bike up 65 widely spaced stairs for 100 yards in the
dark _is_ an unusual need, Jay. It's unusual even in Portland. What
percentage of Portland cycling commuters do you think really do that?

Climbing is also something most people living on the West Coast do
by necessity -- including everyone living on the close-in westside of
Portland. Good low speed light output is not an unusual need.

Climbing is something bicyclists in my area do by necessity, too. I
know several bike commuters in my suburban area, and almost all of them
have to climb out of the area's river valley to get home from work, just
as I did. Climbing is also something done by randonneurs and tourists.
You don't seem to believe that those of us with dynamo lights actually
do these things! Please, discard the Scharfian myths that claim
everything east of the Rockies is dead flat.

Anecdote alert: My wife and I are Warm Showers hosts. We've hosted
quite a few touring cyclists over the years. One couple retired in the
San Francisco area, then headed east to Maine by bike. When they got to
Maine, they decided they were having so much fun they'd keep going,
heading to a friend in Texas, via Ohio. They contacted us, and we said
sure, they could spend a night here.

When they arrived here, they were absolutely beat. They informed us
that after crossing the U.S., then heading from Maine to Ohio, they
never had hills kill them like the ones in Western PA did. The hills
within, oh, maybe 40 miles of my house. Hell, there's a hill about 7
miles from my house that few members of our bike club could climb
without walking. I'm pretty sure I can no longer climb it, despite low
gearing (24 front, 34 rear), although I used to with higher gears.

Screen shots of beam patterns tell you nothing about low speed performance,
unless there are serial beam shots at progressively higher speeds.
Maybe you could direct me to that page.

I don't think that such a page exists. Now consider why! When
information is valuable to any significant number of people, it seems to
appear on the internet. Yet nobody seems to worry about light output at
super-low speeds. See above: It _is_ unusual to need to push your bike
up 65 steps in 100 yards of darkness.

Another anecdote: In 2003, we rode coast to coast. On the way, we rode
through the Paw Paw Tunnel on the C&O Towpath Trail. It's dark, narrow,
and originally intended for walking a mule with a lantern. It's
possible, I suppose, to ride your bike off the path into the canal.

We had dynamo lights with halogen bulbs. My daughter and I found that
we had to ride at more than walking pace to have our headlights show us
the way, so we did that (with some slipping of the roller dynamos
because of mud). It was a bit challenging given the rough, narrow,
slippery surface, but we did it. My wife elected to use a flashlight
instead.

That was then. Now my utility bike has a hub dyno (so no mud-induced
slip) and a Cyo LED light. The Cyo lights up at a far lower speed than
the halogens did. I'm sure I could ride through that tunnel with no
problems with my current equipment.

It's too bad your light doesn't behave like mine. It does seem like you
bought one optimized for maximum lumens instead of for maximum
practicality.


Oh, by the way, I encountered one other bike with a dyno in the
rack today (Shimano hub, a Lumotec light) -- which brought the total
number of dyno-equipped bikes to two.

Two in your particular bike rack. You _know_ there are many more in
Portland.

See, if I were in your situation, I'd have left the person a note with
my phone number and/or email address. Why not?

--
- Frank Krygowski

On 22/10/14 02:52, Frank Krygowski wrote:

Wow. My town has nowhere near the commuter bike count of Portland, but
I can find other folks who use dyno lights, and ask them to take a ride
with me. Heck, I once had a bike shop contact _me_ to ask me to try out
a certain dynamo. And I'd be comfortable posting a request in our bike
club's newsletter, or to its website. I'm astonished that all those
things are impossible in Portland.

Too bad. I thought things were better there.

I am the only person within the circle of riders I know who uses a dynamo.

Many have show interest, but can't be bothered. They put up with
charging batteries and symmetric beam patterns.

I've noticed a few commuters with dynamo powered lights in Melbourne,
and in fact the hire bikes have dynamo hubs as standard.

Though I haven't been to local bike shops to find out for sure, I
suspect most don't stock anything but battery powered "in your face"
flashers.

I know of one shop near Melbourne in particular that sells and stocks a
range of dynamos and lights.

http://www.stkildacycles.com.au/inde...s-dynamos.html

--
JS

On 10/21/2014 7:08 PM, James wrote:
On 22/10/14 02:52, Frank Krygowski wrote:

Wow. My town has nowhere near the commuter bike count of Portland, but
I can find other folks who use dyno lights, and ask them to take a ride
with me. Heck, I once had a bike shop contact _me_ to ask me to try out
a certain dynamo. And I'd be comfortable posting a request in our bike
club's newsletter, or to its website. I'm astonished that all those
things are impossible in Portland.

Too bad. I thought things were better there.

I am the only person within the circle of riders I know who uses a dynamo.

Many have show interest, but can't be bothered. They put up with
charging batteries and symmetric beam patterns.

I've noticed a few commuters with dynamo powered lights in Melbourne,
and in fact the hire bikes have dynamo hubs as standard.

Though I haven't been to local bike shops to find out for sure, I
suspect most don't stock anything but battery powered "in your face"
flashers.

Oh, they're very uncommon around here, too. Still, I've been a club
member for decades. I know people who use them.


--
- Frank Krygowski

On Tue, 21 Oct 2014 09:49:35 -0400, "Bertrand"
wrote:

I used to ride with a guy who became world class (8th '95 world TT, USPro
champ, dozens of domestic pro wins), and his cadence was probably 60-70
rpm tops on steep climbs, but that was back in the 42/21 days. Mine was
even slower. It wasn't until Lance came along that everyone started
spinning up hill -- probably for the best. I spin now just to survive and
could never return to my Regina Oro 5sp 13-21 (or 19) of yore. Plenty of
people could, though. The world is full of genetic freaks who appear to
defy gravity. I avoid riding with them.

I'm just curious whether there are any physiological or mechanical reasons
why it would be more efficient or better to spin slower on a steep hill than
on the flat at the same power. I suspect that there aren't, and that any
preference for lower climbing cadence is based mostly on equipment
limitations, habit, and a macho tradition that sees triples, compacts, or
giant cassettes as unmanly.

Power is a factor of speed and force, so applying, say X force to the
pedals at 50 RPM is far less power than the same X force applied at
100 RPM - actually the force is measured as a velocity but RPM is a
handy measurement.

see http://en.wikipedia.org/wiki/De_Prony_brake


On the flats, experienced riders seem to prefer higher cadence when going at
higher power. For example, puttering along at 10 mph with my sister-in-law,
I'm probably down around 60 rpm. On a hard group ride, it will be around
90. When Jens Voigt set the hour record recently, I think his average
cadence was about 103. And sprinters at top speed seem to prefer around 120
rpm, deliberately choosing a lower gear when needed to keep that high
cadence.
--
Cheers,

John B.