Recommendations for bicycle generators (dynamos) for lights?

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lionsburg
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Recommendations for bicycle generators (dynamos) for lights?

Post by lionsburg » Sat Jan 14, 2017 10:38 am

Hi folks,

I'm looking for recommendations on bicycles generators (aka dynamos) - something that would attach to either the tires or chain to help power LED lights as you peddle around the playa.

Thanks in advance,

-- Michael

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Elliot
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Re: Recommendations for bicycle generators (dynamos) for lights?

Post by Elliot » Sat Jan 14, 2017 11:58 pm

There are definitely generators which run against the side of a tire. They are usually clamped to the front fork. They are roughly the shape of a small bottle, and the "cap" is serrated so it gets a bite on the sidewall. They pivot on the mounting bracket, in such a way that a spring holds it either against the tire, or away from it, as needed.

Such generators are practically standard equipment on bikes used for transportation all over the world. Or at least they used to be.

The down-side, of course, is that when you are stopped, you are a darkwad.

LEDs draw so little juice... one set of batteries may last you all week.

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Re: Recommendations for bicycle generators (dynamos) for lights?

Post by Traveller in Time » Sun Jan 15, 2017 4:38 am

I use a dynamo for my daily bike lights. Over time I have replaced the incandescent lights with LEDs. You will need to add a small rectifier.
By also adding a capacitor you extend the LED illumination by minutes. Adding a modern, larger capacitor or even small rechargeable batteries can extend the illumination time to hours :D.

Not using batteries means you always have light and never have to discard of them.

Make sure your dynamo is a recent one, the ancient types used weak magnets and give low output with high friction where modern may be several times more efficient.
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Elliot
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Re: Recommendations for bicycle generators (dynamos) for lights?

Post by Elliot » Sun Jan 15, 2017 10:19 am

Oooo.... They put out AC....
I used them for years when I was a youngster in Europe, but never realized that. So they are alternators.

So... for DC... maybe -- maybe -- you could use an alternator from an automobile. A tiny one from a tiny car. Modern automobile alternators have a rectifier built in. But you might not be able to spin it fast enough to put out anything. Worth an experiment!

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Re: Recommendations for bicycle generators (dynamos) for lights?

Post by Traveller in Time » Sun Jan 15, 2017 12:23 pm

:? The car Dynamo also has to use rectifiers to make it DC, perhaps you could disassemble one for the rectifier though they (rectifier bridge or four diodes) should be less the a dollar the piece.
The bicycle dynamo has one connection to the chassis and one isolated at the bottom.
First step is getting both to an isolated box where you connect a bridge rectifier.
(use the leads marked ~~ for the dynamo side)
Now you have a sort of DC at the + and - leads. This DC is sufficient to light up LEDs though they will blink visible at low speeds. Adding a capacitor (or some 9V of rechargeable small batteries) will reduce/ eliminate the flashing. The batteries may require some extra resistor == a few feet of thin wire, to extend there life expectancy. Mind the polarity, an electrolytic capacitor has a marked zero or minus and the batteries (most often) have a negative house and a small positive cap.
Use an isolated two wire system for your bicycle power grid :D you can NOT reuse the chassis.


Edit:
You actually do not even have to use rectifiers and stuff, the LEDs are already light emitting Diodes :D just add a resistor (== few feet of thin wire) and they will give some light .
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Re: Recommendations for bicycle generators (dynamos) for lights?

Post by BBadger » Wed Jan 18, 2017 2:24 pm

Is a dynamo really worth the effort? Sure, a dynamo is probably nice for lighting up a commute bike or something like that. On playa though, the dynamo can be ruined by the elements; it will only light up your stuff temporarily as you move; and quite frankly the lighting is boring and not colorful.

Plus, those dynamos aren't that cheap. I saw one on Amazon for like $30 ($15 for the cheapest piece of shit), but you can be paying a hundred bucks or more for a setup. Then as described above you might even need some backup power to keep it lit when you're not moving.

Compare that to some lights that'll last all week on battery power (like cheap AA fairy lights), and a headlight you can use elsewhere away from your bike if you need to light up your way. Plus having a nice unique colorful "light signature" makes your bike easier to identify when you've parked it among a sea of other bikes at night.
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Re: Recommendations for bicycle generators (dynamos) for lights?

Post by Captain Goddammit » Sat Jan 21, 2017 4:35 am

Totally NOT worth it! LED lights are efficient enough that battery life won't be a problem, and you can bring a spare set or three for less $$ than buying a dynamo.
Using the batteries won't add drag while you pedal.
On the playa, you're often going very slow and/or stopping. Dynamos suck in that application.
It's extra junk and wiring on your bike when you need simple and reliable.

Just get an LED light and some batteries and be done with it.
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Re: Recommendations for bicycle generators (dynamos) for lights?

Post by DoctorIknow » Wed Feb 08, 2017 10:48 pm

I've had those "side of the tire" gennys and the more efficient "spins against the outside tread surface of the tire by being mounted where the kickstand is mounted", but both cause drag that is noticeable. Both I'd never consider taking to the playa.

Battery powered lights are cheap and work, but I've had my lights stolen off my bike before.
I've lost my always carrying at night flashlight before.

I needed a backup that stays on the bike and highly theft resistant!

I've used these frictionless front and rear lights for 10 burns now. I love the technology of the "flipping" magnet to produce electricity without those horrible "rub on the tire" generator/dynamo lighting systems.

However, it truly is a "backup" as the light isn't continuous, but flashes twice for every revolution of the wheel (two magnets on individual spokes.) When all else fails for whatever reason, these lights won't help you see where you are going, but let others see you quite well:

Here's the manufacturer: http://www.freelights.co.uk

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