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.






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




And the only reason most buyers of battery lights don't agonize over

reflectors, beam shapes, etc. is because their thought process stops

after "This one's on sale, and gee, it looks bright when I shine it in

my face!" Anyone who seriously shops for a light - battery or dynamo -

should be looking at the beam shots posted on the web.


Have you bothered looking at decent battery lights? And by the way, I looked at on-line beam patterns -- many were disturbingly pitiful, but the SuperNova looked promising.

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.





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?

And about my unusual needs -- almost any of the 500 lumen lights at the bike shop would suit my needs. But with dynos, I have to have an advanced degree to pick a light? Crap, with my battery light, I hit a fast downhill, and I just up the output. It's not like I have to stop and select a different light or add a light.

-- Jay Beattie.