PaulRivers

You may know this, but it's bizarrely far, far, far more complicated than how how much light is on the road.

Obviously an area already lit up fully and completely doesn't need a light, except as a "be seen" device.

Counterintuitively, the place where you need the least amount of light is in the middle of nowhere with no ambient light. If I'm on the local bike path with no extra side lighting, trees on the side that completely block out streetlights, my Dinotte 200L (200 lumens) is more than enough.

The problem is that your eyes adjust to the amount of ambient light around you. I mean your pupils dialate or contract, etc.

Riding with bright but intermittent and uneven street lighting is the 2nd worst. Your eyes adjust to the brightest part of what you're seeing, while what you need is to be able to see in front of you all the time.

The absolute worst is riding where your eyes get directly hit by headlight beams, as again your eyes adjust to the brightest light.

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And if that's not enough by itself, the beam pattern of your light is huge as well.

A bad beam pattern will have a hotspot that your eye adjusts keep, reducing your ability to see other things. It's far better to have a good beam pattern with half the lumens than to have a bad beam pattern with twice the lumens.

One of the reasons why dynamo lights work well is because most models (both the Lumotec and the Phillips from above) have a shaped beam that specifically evens out the beam pattern and light distribution from the beam.

Yet another factor is how increasing the lumens/lux from a light, given the same beam pattern for both, will often result in a suprisingly low perceived increase in light. Double it and the eye only perceives it as being like 10-20% more light...

PlanoFuji

Yep, the details are far more complex (they usually are); however, the examples are close enough to give someone who has never seen one of these lights at night a feel for the light level we are talking about.

ajshine

Well sure. I don't want to be told what to purchase. But I do want more than marketing mumbo jumbo or your anecdotal experiencevto inform my selection.

tsl

I've been car-free for 14 years, the past seven of them by bike.

When relying on bikes for 100% of my transportation, I found that anything that reduces fuss and bother is a good thing. The dynamo lighting system does just that. There's no fuss or bother to riding in low light or night time conditions. Just hop on the bike and go.

Better still, there's no hassle when parking. I don't have to strip off the lights every time I park. The lights are bolted on, and I have bolt-on skewers.

I've had dyno lights on one bike since autumn of 2009. I'm upgrading the lights (to a Luxos U) on that bike and will move the existing ones (Schmidt Edelux) to my secondary commuter and will order another front wheel for it.

That said, re-read what PaulRivers says above about how conditions affect how much light you need. Depending on circumstances, I'll supplement with a battery light.

The brighter the city lights, the more light I need. The dyno light is more than enough out in the unlit suburbs. Downtown with the brightest security streetlights, I need more, mainly so I don't blend in the background lights. In residential areas, it could go either way.

Even so, IMHO the convenience of the dyno outweighs the cost and other factors.

calyth

So how does these hub dyno work? replace the front wheel, and then how does the power get transferred from the moving hub to the wires leading to the light?

I'd like to figure out how much work this is going to be compared to using a high power battery light. Soon enough the usable daylight will shorten up here.

fietsbob

Hub dynamos are alternators , the generator in the cars are alternators

a magnet is rotated past a coil of wire, exiting electrons to move in the metal of the wire .

they dropped science from schools up there? https://auto.howstuffworks.com/alternator.htm

Quote:

how does the power get transferred from the moving hub to the wires leading to the light?

a plug in the Rt side of the hub.

tsl

Just plugs right in.



NOTE: It's an old pic from before I cleaned up the wire routing.

calyth

I actually know how an alternator works.
I just wonder whether I would need to route something to directly connect the hub to it, or if it's possible for this to be done without direct contact, e.g. the magnet is on the hub, the coil is on the forks.

Thanks tsl for the picture. Did that extra piece that you plug in cause any problem fitting the hub in the fork?

fietsbob

Reelight https://www.reelight.com/ has a system more like you describe , long spoke mounted magnets,

and the induction coil of wire part is on the fork.

other than that you need a connection plug into a hub dynamo, 2 wires .
where the plug is located, in relation to the fork tip,

is dependant on the person installing the wheel in the fork , each time.

Though if you are buying a custom made bike, Schmidt has some special models and a fork tip contact scheme
so the act of putting the wheel in the fork also makes the wiring connection for the Dynamo .

PlanoFuji

One note about the Ree lights. They are a lot less bright than even the old halogen dyno lights. They are more of a be seen option as opposed to helping one see.

calyth

Guess I should revisit my road bike maintenance book if I want to replace the front hub with a generator hub then. I would want something that's bright enough to see. Got enough blinkies to be seen.

Thanks all.

tsl

No. If you look at your existing hubs you'll see a whole lot of space between the spokes and the dropouts. That's where the connection resides. Even with it there, there's plenty of clearance on both sides.

The connection is on the axle and you can rotate it to wherever you want until you tighten the QR (or bolt-on skewer in my case). Then it stays pointed where you put it.

The plug snaps on tightly enough that it keeps water out and stays connected no matter what. Right up until you pull the wheel out of the dropout without remembering to unplug first. (I never remember to unplug it first.) Then it just lets go.

Shimano's plug is universal WRT the wires you use. The male side is on the hub, and the female side goes on the wire. You strip off a half-inch of each conductor, feed them through the top of the two-piece plug, and wrap them around the outside of the plug. Snap the two pieces together and Bob's yer uncle.

EDIT: I believe the coils are on the axle and the magnets are in the hub shell. The magnets rotate around the coil. Thus, a brushless connection.

calyth

Neat. Something for me to ponder when it gets darker. That would be soon enough.

PaulRivers

Compared to the battery light you chose - the Lezyne Power Drive XL - and based on my experience with another 400 lumen light, and the Lumotec Cyo, I think the dynamo will definitely be better (visually brighter) than the Lezyne.

On my road bike where I can't use a dynamo, I use 2 Dinotte 400L's, so 800 lumens, I feel like it's a wider beam than my Cyo (something the Luxus U or B does better according to the beam shots) but otherwise not better for throw, visibility, etc. And that's at twice the lumens.

I have to put out a rediculous amount of light to get a "like riding in the daytime" experience - a Light and Motion Sec 900 on high, and a Seca 1400 on medium, so 1650 lumens or so altogether. I don't really use it though, because it blinds anyone in front of me. (Point being that to get a battery light that's significantly better you have to spend a lot of money and run into other problems - and it's not going to have a > 2 hour runtime).