I thought this question might be better posed in a bike forum, but I’m not a member of one, so here it is.
I had a good idea, but its too good of an idea to not have been done before.
The idea is a bike headlight or backlight that uses the bike wheel going around as a generator for power to light it up.
Does something like this exist?
Can I get it at a local bike store or someplace online?
Thanks everyone
I don’t think so, because for it to generate power, there would ahve to be a generator piston thing attached to the hub or rim, and when the rim or hub turns, it would make the piston(or something else) go back and forth generating power to fuel the headlamp. I think it would have ot be somehting custom, not something you go out and buy from a store.
I could be wrong though.(can’t we always?)
I used to use the bottle/tire driven generator types on my Schwinn Continental back in the '70’s.
A quick Google of “Bicycle Generator Light” will give you a bunch of links from cheapos to expenssive.
An example is at http://www.peterwhitecycles.com/lightingsystems.htm , check out the first two systems: one is a hub system, the next is a bottle generator system.
I don’t know if a uni would provide enough rpm to give decent light. On the other hand, you’re not going as fast as a bike so a dimmer light may be sufficient.
i used to have one when i was little, but it wasn’t strong enough on my little kids bike to actually use to see, it was more so that people could see you.
the targets around here carry them, so that would be a good place to check. or walmart..walmart has everything.
been done. to get one that doesn’t suck it is either going to be $500+ dollars or be such a drag on your wheel that you wouldn’t want it. someone(i forgot which company) makes a hub for biek wheels that is pretty good and not too much of a drag for about $300, you still need compatable lights though. a customer at my shop had one on his bike when we were repairing other things, and the lights were pretty bright, but the drag was noticable, at least by spinning the wheel by hand in the repair stand.
for unicycling a good helmet mounted light is probably the best way to go.
In some European countries, almost all the lights are generator lights. They do not have to be expensive. http://www.peterwhitecycles.com/dymotec.asp for a sampling.
Personally, I think the advent of the LED light has made generators not very interesting any more, but if you’re looking for a front light which is good enough to actually help you see, a generator will do better than an LED, but not as good as a big battery light.
I know your asking about generators, but I agree with tholub, that LEDs and HIDs make the ol generator less exciting these days.
I ride my uni and bike with last years model of this. Expensive, but it will turn night into day.
we call them Dynos, they were all the rage in primary school. you werent No one unless you had a Dyno
My Accessory cycle has a tire-driven generator, which used to power a headlight, tail light, and two side marker lights. Not very well, I might add, as I was running too many lights, and a unicycle doesn’t go very fast. Scroll down this page for a closeup:
On a safety note, the problem with dynos is that when you stop so do they, so when you’re waiting at the lights the cars coming up behind you can’t see you.
Re: Bike (or unicycle) light powered by the bike (or unicycle)
On Mon, 6 Nov 2006, kington99 <> wrote:
>
> On a safety note, the problem with dynos is that when you stop so do
> they, so when you’re waiting at the lights the cars coming up behind
> you can’t see you.
Standlight.
My dynamo-powered lights stay on for about 4 or 5 minutes after
stopping.
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Many old bikes used to have those. In fact, my moms old bike has one.
As a kid, my sisters and I shared a bike that had a hub dynamo. The electrics were built inside the hub. Obviously far less easy to install one of these onto a unicycle I would guess.
I didn’t like the tyre driven generators. They seemed to cause excessive tyre wear. But if there was enough friction to allow powering from the rim rather than the tyre it might work better.
I suppose a warning flash could also be fairly easily rigged up by using rare earth magnets ( Neodymium ) and magnetic induction principles, but this would be unlikely to be easily able to provide “see-by” light intensities.
For the principles involved see the “magic forever flashlight” as shown here:
http://www.aria.co.uk/ProductsList.asp?Name=torch
You might even find a way to use one of these in your design. They work, but light output would not suffice to light your way. I think they use a capacitor for storage, to allow a few minutes of power.
Nao
I was once on a bike tour on a bike with a generator light, and got lost out in the farmlands after dark. To read the map, I had to set the bike upside down so I could turn the cranks.
I used to have one: the light’s intensity was linked to how fast it was pedaled, but the drag it put on the tire made it nearly impossible to keep a good ratio of light/speed-- of course that was probably back in 1992.
The real question: Is there a tire driven generator that could be easily installed in my apartment?
Re: Bike (or unicycle) light powered by the bike (or unicycle)
On Sun, 5 Nov 2006, James_Potter <> wrote:
>
> I had a good idea, but its too good of an idea to not have been done
> before.
Correct.
> The idea is a bike headlight or backlight that uses the bike wheel
> going around as a generator for power to light it up.
> Does something like this exist?
> Can I get it at a local bike store or someplace online?
It’s normally called a dynamo, though technically it’s an alternator.
There are good ones and bad ones. Good ones are reasonable, bad ones
are more-or-less useless.
The best is a hub dynamo, built into the front (usually) hub of a
bike. They have almost imperceptible drag, can easily generate 3W
(which is a decent amount of light if you use LEDs) and at high
speeds with the appropriate circuitry can generate twice that. The
very best of these is the Schmidt SON, which is a very finely
engineered piece of german precision. For utility commuter bikes,
where you want to always have lights available, without worrying about
batteries or packing the lights, these are very good. Combine with
LEDs, and you don’t need to worry about bulbs either - fit once, and
have light whenever you need it.
If you have a dynamo that runs on the tyre, that’s normally called a
bottle dynamo (it’s shaped like a bottle, with a roller where the
bottle cap would be). Again, nominally 3W is normal. These have
higher drag than a hub dynamo - it’s distinctly noticeable. The two
best are the B&M Dymotec S6 (but not the Dymotec 6 - that’s a lesser
model) and the Lightspin.
Cheaper ones have higher drag and no more power. Drag is significant
for more than simply how hard you have to pedal - when the tyre gets
wet (riding in the rain), the roller can become prone to slipping.
The higher the drag, the more likely it is that it will slip. A cheap
dynamo is almost guaranteed to slip in the wet, but my B&M S6 has
never slipped. Bottle dynamos need care setting up - if you don’t get
the alignment right, you make slipping more likely, and you can
damage the tyre.
There are other more minor types of dynamo - bottom bracket dynamo
is a cylinder that runs on the running tread of the tyre (less
alignment problems, more crud problems, no hope with knobbly tyres),
there are some that engage on the spokes.
As speed increases, the dynamo generates more power, and does so by
boosting the voltage without generating much more current. Expensive
dynamos have regulators to dump the excess power somewhere safe, but
cheap dynamos won’t, and may be prone to blowing bulbs.
Also, they have a habit of blowing bulbs in pairs - the dynamo wants
to generate a set amount of current, and will fluctuate the voltage
until that much current flows. If you have two bulbs in parallel, and
one blows, the dynamo will try and put all the current through the one
remaining bulb, even if that means a sudden dramatic voltage increase.
This can cause the second bulb to immediately blow. Again, decent
lights and dynamos will have some form of regulation to try and
mitigate this.
If you have clever circuity you can use the extra power a fast running
dynamo gives you - a hub dynamo that is nominally 3W will drive two 3W
lights if you’re going fast enough. You can buy lights that do this
automatically (eg solidlights 1203D), or you can wire in two lights
with a bypass switch that you flick when you are going fast enough.
The other clever circuitry thing to do is build in a small power
store. Normally a big capacitor. My lights have a 1.5F (yes, one and
a half whole Farads) capacitor in the circuit. This charges up in
about the first 100yds or riding, then if the dynamo stops, the
capacitor supplies power for a minute or so. These are called
‘standlights’, and it means the lights don’t go out when you stop at a
junction.
Finally, you can get systems that use magnets on the frame that topple
a magnet in a coil fixed to the spokes. These are fun novelties, if
you want twinkly lights on your wheel, but no-one has produced one
that generates useful power for actual lights to see by.
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I saw one already. There so cool.
How large is the capacitor? The smallest ive seen at that capacity are used for car stereo applications and are around the size of a drinks bottle. Any idea what the dielectric is?