Greg M

So all these comparisons between rechargeable lights , battery and dynohub lights
I realise I know nothing how a dynohub light works. So I'm riding to work in the dark ,
and as I coast to a stop at a traffic light does my light dim then go out ? And if it does
how is this better? Iwouldn't feel comfortable waiting with no light. Do you have second
battery light on at the same time ? I always have a backup ready to go at anytime.
Having to remove my light every other day to charge is annoying. So I am interested
in the possibility of setting up a wheel with a dynohub also because I'm planing a short
tour this summer involving some camping.

cycle_maven

It depends how tricky you want to get with your lighting. Some lights have a standlight feature that will keep the light burning for a while if the generator stops putting out juice. But they're more expensive than just a simple bulb in a socket.

If I were going to the expense of a generator hub, I'd get a good light, too. Maybe something with a big Cree LED emitter and a small battery. The folks at the lighting forum topic could help you much more.

dscheidt

Essentially all modern LED dynamo lights have a stand light, which is large capacitor that keeps the light lit, at reduced brightness, for several (5 to ten, give or take) minutes. Long enough so you're lights will work even at a long traffic light.
There are some lights that don't have a standlight; there's no good reason to buy one. the price differential is small, and the lights aren't brighter because of it. That's true of both head lights and tail lights. taillight stand lights tend to stay on longer.

I don't notice any difference in brightness as I'm slowing down; the lights (I've several different models on different bikes w/ different hubs) tend to apparently full bright at just over walking speed. (They aren't really fully bright until 10 mph or so, but a plain eye can't easily tell that.)

fietsbob

+1 the better head and taillight designs include a capacitor. that stores a few minutes worth of power

collected, as the wheel turns at an adequate speed for an amount of riding time.

Greg M

Thanks, my day is complete , I've learned something new.

Matariki

My dyno lights stay illuminated for at least 5 minutes without moving. I am using the Busch and Mueller Lumotec IQ Cyo in front and their TopLight Line in the rear.

vanttila

The problem with most dyno's is that they take away from your pedaling to light the thing up, and often aren't very efficient in doing this. In other words, you can feel the difference, at which point you wish you never had a dyno in the first place. Sure you can get a better dyno, but it costs more, and at that point, you could've gotten a much brighter and nicer flashlight that runs on 18650 li-pos which last practically forever. You can get great deals on Ultrafire flashlights like these online, btw.

mrbubbles

Everyone do yourself a favor. Please ignore the post above.

vanttila

Oops, I may have skimmed over the OP's question a bit. It's dynohubs he's talking about. Still, if he doesn't have one now, it may not make sense to buy one.

MichaelW

Modern Dynohubs from Shimano are so efficient that it is hard to tell if they are on or off. The pulse you feel when you spin the wheel by fingertip is a magnetic resistance followed by a magnetic acceleration to the next resting point, over the space of a few degrees rotation. When combined they almost cancel out.

Standlight headlights switch to dim standlight mode about 1/2 second after the wheel stops spinning. As soon as the wheel rotates it springs back to full power. Wheeling the bike it is on full power but flickers until you reach 3mph (German standards). If you run out of standlight at a long stop, you have to lift the front and spin the wheel a bit by hand but Ive never had to do this.

You can't repair a puncture by dynamo light, you need an auxilliary battery lamp. I carry a small LED watch battery backup.

A dynohub can be used to power the front only or a f/r combo.

unterhausen

I have the cheapest possible dynohubs on a couple of my bikes, and the drag is imperceptible. On my road bike I still out-coast just about everyone I ride with except for maybe some recumbent riders

vanttila

Directed at the OP, who said he knows "nothing" on the topic: From a quick googling I found that most dynohubs today draw 3 watts. If the OP pedals at 80 watts avg. during his summer trip, that's a bit under 4% of his power that goes into the light. That's not major, but worth noting. In addition, dynohubs weigh 1lbs and up, though the weight is at the center of the wheel, which lessens the power wasted in this (the rotational energy for a heavy wheel is higher, and it's all wasted when breaking, so lighter wheels are better). In addition, setting up a dynohub requires building a wheel around it (or buying one that comes with a wheel, I suppose), which may or may not be a problem depending on the OP's skills and budget. Dynohubs alone cost $100+.
Once you have the dyno set up, it's true that you have one less thing to worry about, and you "won't have to remove your light every other day to charge." Still, I'd recommend investing in a quality flashlight, handlebar mount, and a battery charger, with a couple of spare batteries. Buy them online from dinodirect, t mart, or another such place and you can get the whole deal for <$25. I ride home in the dark 5 times a week and only need to change the battery once a month if that.

debit

Why would it not make sense? I didn't have one, wasn't satisfied with my the feeble light of my rechargeables, so I bought a SA dyno hub with drum brake and built a wheel. (And dyno hubs don't have to be massive and clunky. I think I'm going to get one of these next and built up something light and fun.) I'm so much happier now that I can see clearly on my way home in the dark.

vanttila

I was a bit hasty with the first comment, my apologies. To answer your question, see the comment 2 up from this.

clasher

I used to commute all winter long (~10km each way) with bright Busch & Mueller dyno lights. I had a sturmey-archer drum brake/dyno front hub on one bike and a high-end shimano hub on my long-distance bike. Both hubs were great at powering the B&M lights which have amazing optics that project the light onto the road surface rather than up into the air or drivers eyes. I used to use planet bike lights which work fine for being seen but the dyno lights mounted above the fork crown are far superior to anything on the handlebar for illuminating the road. If they're mounted with security bolts they are tougher to steal than most handlebar mounts too. 200$ is a bit steep but it'll get a pretty sweet set of lights and a high quality hub, especially from European online shops, particularly bike24.com

I know that the small weight of the dyno hub and slight drag of the hub never made a discernible difference to my commute times or even times on longer rides... other factors always took bigger bites out of my time, namely stop lights on my commute and weather factors on longer rides. I don't sweat a few pounds (water is heavy for e.g.) either way on a bike, especially riding in the winter with boots, gloves, heavy coat, etc. it's all a wash. I like the "set & forget" aspect of dynamo lights too, if you keep your bike in a secure garage or something you can just leave the switch on and have daytime running lights... the only reason I turn my off is to keep helpful people from telling me my lights were on.

debit

@ vanttila The OP mentioned camping/touring in his initial post. I really doubt that he's going to worry about how one more pound affects his speed v. effort if his bike is loaded for touring.

OP, check out this article for some helpful information on lighting and dynohubs, and then this one which has links at the end about weight and friction costs. And if you don't know how to build a wheel, head over to the mechanics section. They can steer you to the right places to start. Or check out your local shop or coop for classes. It's easy, fun and really satisfying to roll out on wheels you built yourself.

vanttila

The article certainly shows that the weight and friction costs are minimal. Suppose it comes down to are you willing to pay (in dollars) for the convenience of not having to change your battery/having the light in a better spot?

dscheidt

I change the batteries in my lights never, because they don't have any. I ride in the dark an hour a day or more this time of year. I run the lights all the time, because I really cannot tell if they're on or off. If I were worried about a pound or two, there are places that are much cheaper to get rid of them than on my bike...

I build my own wheels. So the cost difference for a dynamo hub was about 20 bucks. I have better lights than any half-assed flashlight mounting system, even on the beater, with a cheap light set up. And they just work. Every day, every night, rain, snow, cold, whether I've ridden the bike in a month. Hop on, start pedaling, and light.

debit

Building a wheel can be expensive, yes. But if you compare the life of the hub to how much you'll have spent in batteries, the hub probably ends up being cheaper in the long run. Better for the environment too. And really, the quality and quantity of light from a dyno hub and some decent lights is better than any battery or rechargeable light I've ever had.

This is what I paid: Lights were from Peter White and I think front and back combined cost me maybe $60 with shipping. The wheel (hub, spokes and rim) was $132, so lets be generous and say it will cost about $200 to get set up. $200 would buy a lot of batteries, true. But I'm really happy with my set up and consider it money well spent.

vanttila

I suppose the OP now knows just about everything he needs to know about dynohubs. Mission accomplished, eh?

tsl

In that case, consider the B&M Luxos U headlight. The U stands for USB. It will power/charge USB devices as you ride. It's suitable for phones, GPS units, and the like--low-power devices. Has a nice daytime running light mode as well. It's not a bad headlight either. However above 17-18 mph or so, I feel like I'm overrunning it.

My other bike has the original Schmidt Edelux light (as opposed to the updated Edelux or the new Edelux II). That light's good for up to 25 mph. Real nice "throw", but it's a fairly narrow beam and pretty dim up close to the bike. The newer versions are supposed to light the near-field better than mine.

One thing about the Edelux is that it has an ambient light sensor to turn it on and off. I mention this because when it does, I cannot tell by pedaling effort or feel. In broad daylight it will switch on under bridges and off again coming out. The only way I know it does this is from the reflection on the fender.

Yes, some of my effort goes into making electricity. No, I can't discern a difference in the bike--or more importantly, in my quads--when the light switches on. It doesn't suddenly become easier when the light switches off either.

Finally, yes, dynamo systems are the most expensive way to make light. (In the USA anyway. Acidfast will chime in here shortly telling us they're really cheap in Europe.) There are also battery systems that are considerably brighter and cheaper at the same time. Only you can decide for yourself whether or not the convenience and security are worth it to you. I decided to equip both my commuters with them. Took me four years between the first and second one, but I'm happy with them both now.

Walter S

For lights alone, I think your statements are reasonable. I have a dyno hub and use it for various electronics such as my iPhone. While I could charge these things at home, I'd rather not mismanage the batteries and discover at the wrong time that they're dead. But the dyno hub pays off biggest when I'm touring. I don't need to stop at a motel or go hang out at a library or something just to charge my phone. My power is self sustaining for days or weeks or months on end without access to electrical outlets.

unterhausen

I can't see having a bike without a dyno any more. I just bought a fatbike, and it doesn't have lights. It feels limiting. I just can't imagine a commuter without dynolights at this point. No worry about battery management. I think I'd feel that way about a touring bike too, you eventually are going to want to ride at night.

CrankyOne

Forgetting to charge, forgetting to take a light with me when my return will be after dark, and not worrying about theft (or having to carry lites around with me so they won't get stolen) are the biggest reasons I like dyno's. They're always on the bike and they always work.

vanttila

I hadn't even thought of that. Definite advantage there. Just outta curiosity, how long do dynohubs typically last?