brianinc-ville

Hi. I've got a '74 Raleigh Superbe I'm using as a frequent commuter. As the days get shorter, I feel like I need a better headlight. Right now I've got a Busch & Müller Classic N (which is the Lyt in a silver plastic shell), but A) it doesn't have a standlight and B), more importantly, it's just not bright enough, especially at low speeds.

What current-production (2019) dynamo headlight would you recommend, to get the most out of the Sturmy Archer GH6 dynohub's output? Ideally, $100 or less.

Also, I remember BF user @minisystem 's ingenious hub magnet upgrade from years ago, but I'm not quite up for that level of engineering -- but has anybody made a drop-in solution?

Thanks!

Road Fan

I would suggest a modern B&M with their excellent optics and efficient LEDs. They don't really need the full output of a SON, so with the lesser spec of a GH with added consideration of potential decrepitude, I would think an LED headlamp should work well. But I haven't tried it, nor do I know anyone who has.

I know I toured 10 years ago with a halogen B&M and a 35 year old Soubitez bottle dyno. It worked very well.

The electrons from a vintage dyno are the same as the ones from a modern dyno. Question is are there enough of them (current) and will they fight hard when they are produced (voltage)?

brianinc-ville

Right. Like I said, I already have an LED lamp from B&M, and it's not good enough -- but it's one of the lower-end models (25 lux). My question is whether there's any point in buying one of the higher-end B&M lights (say, the IQ-X, rated at 100 lux), or whether the limited current output from the vintage hub simply won't do the job.

nlerner

I believe @rhm has run modern optics off of S-A Dynohubs though those were his home-brewed LED lamps.

rhm

I have the same experience and the same question. As @nlerner mentioned, I have done quite a few experiments with these hubs running LED lights I assembled myself. But this was a dozen years ago, and at that time, my home-made lights seemed to be as good as anything I could buy. But LED lights have come a long way since I started making my own.

My Armstrong bike has a GH6 hub and rather weak modern LED lamp. I don't remember what it is, 30 or 40 lux, and it's not really enough. I have much better lights on other bikes but haven't tried them with the SA.

My suggestion would be: you need a better light regardless whether your SA hub can power it or not. So get a better light. I like the B&M cyo premium 80 lux model, but I don't think it matters as long as you get something good. I can't promise it will be as bright when powered by an GH6 as it would be when powered by a modern hub, but I'm sure it will be brighter than what you have now. If it's still too weak with the GH6, then you can consider upgrading the hub (but I hope it doesn't come to that) or using the more powerful light on a different bike (with a modern hub).

gugie 

Peter White has more info about generator lights than anywhere else. He points out, correctly, that it's not just the lux or lumens, it's where the optics place the light. Most people agree that B&M has the best optics.

https://www.peterwhitecycles.com/headlights.php

tacreamer

Spanninga Axendo 60 Xdas (standlight/automatic/DRL) dynamo bike headlamp $55
https://rover.ebay.com/rover/0/0/0?m...2F283498566248

This is the same light as the Phillips 60 lux headlamp with daylight running lights. I’ve both on different bikes.

1984 Miyata 1000 Edulux 1

Litespeed Classic B&M battery lights - B&M 70 Lux

Alex Meade - Edulux 2

Soma Tour - Edulux 2 - B&M battery lights

Rawland B&M 60 lux

Yellow Bacchetta B&M 100 lux

Red Bacchetta B&M 100 lux

Shirley Pacer B&M 40 lux

Soma Double Cross Phillips 60lux

1984 Trek 520 Spanninga Axendo 60

Karate Monkey Sinewave triple

All bikes Supernova & super taillight quick setup

Road Fan

As an electrical engineer, I do not have the numbers I would need to predict for you whether a higher-end B&M will actually work, though such a prediction is definitely possible with the correct data. What I tried to say to you was that I think it might work. I recall that the claimed output from the GH is enough to supply any of the B&M lights. The unknown is whether a particular GH is performing up to specification, after perhaps 60 years of time in the field. Magnets can change due to how they are handled over time. If the strength of the magnetic field becomes reduced, the output (probably the short-circuit current) will decrease accordingly. To determine that requires disciplined testing.

But essentially, all dynos have to when new produce more than the rated output at higher speeds. In the first place there is variation among samples for any manufactured item. So while all must satisfy the German regulations at the specified road speed, the vast majority will exceed that spec by some amount - it's just statistics. They will also all exceed the specification output when tested at a higher road speed, or in a test which simulates a higher road speed. Output from any generator (bike, car, municipal power, et cetera) is at higher voltage at higher shaft speeds. If you've read the efficiency tests for generators published by Jan Heine, you can see this. This is also true when it is aged, but the question is still how much lower than spec will it be.

So as I see it you have several options depending on how much money you have to put into the solution and how long you can wait to have what you need.

1. Seek an electrical engineer/cyclist who is set up to evaluate the situation properly. That person is not me. My SON works very well with a Luxos (about 80 lm if I recall), the lower output one.
2. Send your questions to Peter White at Peter White Cycles. He is the importer for B&M and he keeps a Google group where people discuss such matters directly with him as well as with each other. If he knows he will speak up. Join the group, have a discussion.
3. Read his website to find the terms of his return policy, and it it's acceptable to you, buy the light that you need and just hook it up and see what it does. B&M makes bottle dynos that are capable of running the bigger lights. Testing it like this is probably the second quickest solution. If it doesn't work, see what generator Peter recommends. He can get the best available information from the factory.
4. Buy the better light, a SON or SP dynohub and have a wheel built. More $$ but problem is solved. This is certainly the quickest solution.

Sorry for any confusion I may have caused.

Road Fan

Rudy has as usual summed things up way more concisely than I did!

clubman 

Calling @BigChief ?

Road Fan

I like what @minisystem has prototyped, but he has not gone into production, and it seems it needs some electronics to keep from over stressing LEDs.

What would be a drop-in solution? I can only see a light replacement. On the generator side, replacing it with a better dyno is a wheel rebuild. Replacing that ring of magnets by doing something like what Mini did, based on total disassembly and rebuild, in addition to engineering and fabricating the parts. Then the possibility of needing to regulate or limit the electrical output. I don't know how much voltage it takes to kill a B&M headlamp or taillamp.

I would suggest a refinement to the Minisystem concept: redesign the magnets and the ring carrier to radius the magnets to make a circle concentric with the rotor poles, and with even spacing to the rotor faces. This improves efficiency and output, and it may change the mechanical feel of the wheel. In addition I might check or improve the bearing quality and radius the magnet inner faces, to make more consistent rotation of the hub axle to prevent scraping between the magnet faces and the rotor faces. Not that I think there is a problem with the mechanical quality, but when you reduce the clearance between a pair of rotating parts, the chance of interference is increased. Knocking a magnet loose will ruin your day.

brianinc-ville

Well, I don't really want to do any design or fabrication myself, but I'd buy an upgrade if somebody else made it. If it were possible to buy a stronger magnet ring, plus an in-line circuit package that would replicate a modern dynamo hub's performance (I use Sanyo H27s on three other bikes and am perfectly happy with them), that'd do it for me. Meanwhile, I've ordered a B&M Luxos B headlamp and will see how it goes.