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Thread: Dynamo Hubs

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    Dynamo Hubs

    So, OK, I'll readily admit to be more than a bit of a geek, so the fact that THESE appeal to my sense of "I WANT THAT" isn't too terribly surprising. Above and beyond lights, I can thing of all sorts of things I could use them for (but then, I am a geek, and electronics design is kind of fun, even if I'm no good at it).

    I guess what I'm wondering is if anyone here has tried them, liked them, hated them, or what?


    Gabriel
    2006 Surly LHT

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    I have a set on my tourer that powers a light on the front. The cabling seems pretty sturdy and the connection on the hub is straightforward. Not an electrician by any means, but I can definitely see the light flicker in time with the speed of the hubs rotation, so that might be a little difficult for wiring, but what do I know. Haven't had any problems so far, and they seem to work out well.

    But generating only 3 watts with 6 volts seems to imply it won't power much beyond a light. If you do anything snazzy with one I'd love to hear about it.

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    Long Distance Cyclist Machka's Avatar
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    Never tried the Shimano, but I've got the Schmidt hub, and I like it.

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    Quote Originally Posted by meteparozzi
    I have a set on my tourer that powers a light on the front. The cabling seems pretty sturdy and the connection on the hub is straightforward. Not an electrician by any means, but I can definitely see the light flicker in time with the speed of the hubs rotation, so that might be a little difficult for wiring, but what do I know. Haven't had any problems so far, and they seem to work out well.

    But generating only 3 watts with 6 volts seems to imply it won't power much beyond a light. If you do anything snazzy with one I'd love to hear about it.

    Well, what I was actually thinking would be to have it do a trickle recharge of batteries for other devices when I didn't need the light. It wouldn't be too hard to do a pi filter with some caps to level out the output of it, plus there are some little semiconductors out there which do a really good job of leveling things out at low voltage levels.

    But I'd need to think about it for a while.

    Thanks for the responses, by the way. I appreciate it.


    Gabriel
    2006 Surly LHT

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    Senior Member royalflash's Avatar
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    I would say that a hub dynamo would be a useful addition to any bike that you seriously intend to ride in the dark regularly like a commuting bike or a touring bike. You are no longer completely reliant on batteries being charged up and always have a basic level of light. Although the light from a 3w dynamo cannot of course compete with a powerful battery powered system like a HID you can always supplement the dynamo with with brighter lights when necessary.

    I have two Schmidt hub dynamo wheels for my winter commuter and would not consider being without them. The extra rolling resistance is negligible and I have a non-Schmidt wheel when I don´t need any light.
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    Quote Originally Posted by G. Hoffman
    So, OK, I'll readily admit to be more than a bit of a geek, so the fact that THESE appeal to my sense of "I WANT THAT" isn't too terribly surprising. Above and beyond lights, I can thing of all sorts of things I could use them for (but then, I am a geek, and electronics design is kind of fun, even if I'm no good at it).

    I guess what I'm wondering is if anyone here has tried them, liked them, hated them, or what?


    Gabriel
    I've got the Shimano 3N-71 shown in the link, it powers a Busch & Mueller halogen headlight. I used this setup for 15 months when I was cycling to work (I walk to work, now) and really liked it. The Schmidt dynamo is a bit lighter, has lower rolling resistance, and the wiring is supposed to be sturdier. I bought the Shimano hub because it was <1/2 the price of the Schmidt, but if I had to do it again I would probably get the Schmidt. The Shimano is better value for the money, but the Schmidt is just a much nicer product. If I get into randonneuring this spring I will probably splurge on a Schmidt, just for the lower resistance and lighter weight, and keep the Shimano setup for utility night riding.

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    Zoom zoom zoom zoom bonk znomit's Avatar
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    Yep, had one on my commuter before I got lazy and started driving the cage to work. They work fantastically well. Used it with a lumotec oval headlight, plenty of light for around town and a "standlight" which is a capacitor powered led which illuminates for a few minutes after you stop at the traffic lights etc. Important if you are using any sort of dynamo powered lighting. The lumotec light also had a sensor so it would come on automatically when it got dark! Clever wee thing.
    The light comes on at a pretty low speed too, you can feel the resistance but its not huge. Remember you will probably have to get a mechanic to lace up the wheel so factor that in to the cost.

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    I have both. While the Shimano 3N-71 hub is not as good as the Schmidt, it still is a very good product. I find that riding with a dynohub is so much better than riding with a battery system, mostly because I don't have to worry about battery life. Compared to the Schmidt, the Shimano feels a bit less "smooth", especially with the light on, and this is not a problem when commuting, but could feel like one if I were riding the entire night on a calm rural road.

    However, I would stay away from the Shimano headlight and get a Baush&Lumb, Lumotec or SChmidt headlight. The Schmidt E-6 is the most tightly focussed and provides a wonderful beam, but the Lumotec (round or Oval) provides a very decent beam and is rather cheap. Both of these have good optics and use a zener diode to prevent overvoltage. So you get a good beam that actually throws light on the road.
    Michel Gagnon
    Montréal (Québec, Canada)

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    Anyone know of a Canadian source for Schmidt dynohubs? Or is everyone ordering in from Peter White?

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    Formerly Known as Newbie Juha's Avatar
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    Quote Originally Posted by Michel Gagnon
    However, I would stay away from the Shimano headlight and get a Baush&Lumb, Lumotec or SChmidt headlight.
    You mean Busch & Mueller lights, right (http://www.bumm.de)?

    One more brand of dynamo lights to consider is Basta (http://www.axa-basta.nl/). My LBS had run out of Lumotecs, so I decided to try out a cheapish 2.4W/6V Basta. It's a very basic model, just on/off switch, but I run it off batteries, so I have no need for standby feature etc. The light pattern is quite good, although I've yet to compare it side by side with my older Lumotec Oval.

    --J
    To err is human. To moo is bovine.

    Who is this General Failure anyway, and why is he reading my drive?


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    ROM 6:23 flipped4bikes's Avatar
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    Maybe you want something like this:

    http://gizmodo.com/gadgets/cellphone...ger-231766.php
    Every time we let a vehicle pass there is a little bit of compromise. But compromise allows the city to function and allows cyclists to function in the city. The trick is not to eliminate compromise but to learn how to work safely within it.

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    Here is a link to a page detailing circuits for powering LED lights from a Bicycle Dynamo.
    http://www.pilom.com/BicycleElectron...moCircuits.htm
    If you look closely at some of the drawings you will note this person included voltage and current ratings for the LED's used. This includes modern Luxeon LED's, which will not tolerate under or over voltage conditions. You could replace the LED in the circuit with a device like a cell phone battery charger with the came voltage and current requirements. A few changes to the basic circuits could have you doing all sorts of fun stuff. It would be easy to power a radio with a dynamo but I found a 6" X 6" solar panel, which will provide almost 5 volts in bright sunlight. It's perfect for powering a small transistor radio using 3 AA batteries. I used some wood dowels with brass screws in the ends to replace the batteries that would normally be used to make hooking the solar panel to the radio easy. For nighttime use or heavy overcast days I simply pop out the wood dowels and install batteries and pack the solar panel.

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    Quote Originally Posted by Juha
    You mean Busch & Mueller lights, right (http://www.bumm.de)?

    Oups! My memory failed. Busch&Laumb is a company making other instrumentation.

    If I look correctly, B&M also sells the Lumotec headlight. As for the Axa-Basta, I don't know it. There is a German website (with "tandem" somewhere in its name) that shows light patterns. It might be worth an investigation.
    Michel Gagnon
    Montréal (Québec, Canada)

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    I noticed Mariposa had put this Shimano hub on a few of their custom bikes, in the 4-6K range. Can't be bad if they are using it.

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    How does a 3W halo bulb down around the fork crown compare to a 15W halo bulb up on the handlebars? (or 2 3W halo bulbs; the hubs can do 2 bulbs, right?) Is it strictly in proportion to wattage, or does the lower mount help out some?

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    Wattage is a poor measure of light output. Even between halogens.

    As for a 3 W halogen bulb in a Lumotec or Schmidt headlight vs a battery-driven halogen headlight, there are a few issues:

    – A lower mounting point means that the beam is a bit more useful.

    – The Lumotec has a well-designed reflector and the Schmidt E-6 has an even better designed one. You might see beam patterns here, here. An E-6 headlight throws light on the road, not in the ditch or in the sky. So all the light is thrown where you need it.
    Rechargeable systems typically use an MR-11 spotlight, so most of your beam is wasted.
    On the other hand, if you ride in the woods with your E-6, you'll painfully discover its limits because you won't see branches, tight curves...

    – Because of their better designs, the Lumotec and Schmidt headlights don't blind oncoming road users.

    As for a quick non-scientific comparison (i.e. my eyes), in 2001, I replaced a 2-year-old Vistalite system with a Schmidt hub and Lumotec headlight. The Vistalite system had a 5 W and 10 W MR-11 spotlights. For commuting and on-road riding, the 3 W Lumotec was definitely brighter than the 5 W spotlight, and about as good as the 10 W spotlight. And because the headlight is larger, I find it is more quickly noticed by oncoming drivers (i.e. they don't turn into me).

    And this year, I replaced a Lumotec main headlight with a Schmidt E-6 one, and noticed benefits.

    As for dual headlights, they are beneficial if you ride fast (more than 20-22 km/h) and in the dark. No need for that if you commute under city lights.
    Michel Gagnon
    Montréal (Québec, Canada)

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    Thanks! Good additional info here.

    I started thinking wattage alone was not sufficient to evaluate lights when I got no real difference (other than shortened battery life) switching from 15W to 20W MR11 bulb.

    As for speed, I do have (unlit) downhills that bring me up toward 40 km/h w/o really thinking about it. Would definitely take effort to keep it down to 25 km/h.

    I wonder about attaching an LED flashlight to the handlebar for having something for waiting at intersections, and also to change flats by.

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    You need a new bike supcom's Avatar
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    Quote Originally Posted by HardyWeinberg
    Thanks! Good additional info here.

    I started thinking wattage alone was not sufficient to evaluate lights when I got no real difference (other than shortened battery life) switching from 15W to 20W MR11 bulb.

    As for speed, I do have (unlit) downhills that bring me up toward 40 km/h w/o really thinking about it. Would definitely take effort to keep it down to 25 km/h.

    I wonder about attaching an LED flashlight to the handlebar for having something for waiting at intersections, and also to change flats by.
    For riding on the road a Schmidt headlight beats any MR11 halogen lamp. You have to see it in person to fully appreciate what well designed optics will do for you.

    Better than rigging up a flashlight is to strap an LED headlamp to your helmet. Works great and lets you see your bike computer, cue sheet, read street signs, fix a flat, etc.

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    Quote Originally Posted by HardyWeinberg

    I wonder about attaching an LED flashlight to the handlebar for having something for waiting at intersections, and also to change flats by.
    Mag-Lite 3-watt LED 2AA Mini-Mag Flashlight. It's bright so you can actually see where your going, has a reasonable run time on 2 AA (or 3 for the 3AA version) batteries, very little weight, adjustable beam pattern and costs less than $25. Use EMT conduit hangers or clamps with bits of rubber inner tube glued to the interior parts of the clamp to prevent scratching the light or handlebar. I also replace the screws that come with the clamps with thumbscrews so no tools are required to remove the light and clamps when not needed.


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