Pedaleur

Hard to say which is a better rating, unless the lux ratings take several targets into account. Otherwise you end up with a low-output, highly-focused beam being the same 'rating' as a high-output, wide one.

tsl

Certainly there are ways to game any system. There's no question that manufacturers can and do game the system (and sometimes outright lie) to make thier product seem better than another. Nothing's perfect.

ItsJustMe

Yes, I realize that. I did take shaped beams and their better efficiency into account when I mentioned a 5 watt headlight instead of my current 8.5 watt one.

However, in the case of taillights, the whole point of them is to smear light all over the place. I run a 3 watt main light and two 2 watt secondary lights. I don't always run all three lights so I figured 5 watts is a good number. I actually probably would only run the 3 watt on the dynamo since the whole point of having multiple lights is that so you can have an entire system fail and still have a light. For the same reason, even if I had a dynamo front light I'd still have to carry at least a hand torch and a lockblock. I've been stuck 4 miles from anywhere in the middle of a snowy, potholed gravel road in the middle of the woods at 4 in the morning before with a dead light, and it's NOT FUN. In that case I had no backup and wound up slowly making my way home by holding my taillight on steady mode in my hand. Also not fun.

As far as new lights being efficient, I suppose the Philips Saferide counts as a new, efficient light. It comes with 2300 mah batteries rated at 2 hours on high. That's 1.15 amps draw at 4.8 volts nominal, which is 5.5 watts power draw. A touch more than the 5 watts I mentioned above (where I was, admittedly, just pulling numbers out of a place).

In any case, if I continued to use a battery powered 2nd taillight, that's 8 watts of draw.

I did think of something else last night on my way home. A lot of the time in the winter (the only time I really need a light), I'm plowing through poorly plowed, rutted mush. I was doing so last night. When the conditions are like this, I'm only going about 7 to 9 MPH at best, sometimes 4 MPH, steering like mad and skidding the front wheel all over to muddle through the criss-crossing car wheel ruts, for 20 minutes at a time. And that's the time when I need the most light, because it's almost impossible to see the potholes through the rutty snow even with a bright light. Also the tail is doubly important on a road where even the cars are mooshing around all over, around bends and hills in the black with full tree cover.

Is a dynamo going to be able to deliver the power at 6 MPH to keep a 1000 lumen light and a 3 watt taillight going indefinitely? 20 minutes is too long to expect a standlight capacitor to hold.

tsl

I continue to run battery lights in addition to the dynamo ones, simply from a belt-and-supenders standpoint. For the record, when I ran strictly battery lights, I also ran two on each end, all powered separately. I've had lights die unexpectedly in a commute, and been glad I had the second.

I'm also of the opinion that standlights on dynamo lights dim too much and then are easily lost among the background lights of the city, my primary habitat. The last thing I want is to start from a light, having someone turn left in front of me because the standlight disappeared among the background lights and they forgot I was there.

Dynamo systems (both hub and lights together) that are in compliance with the German StVZO regulations must achieve full power (from the hub) and brightness (from the lights) by 10 km/h, or 6.2 mph. A homebrew system like you're describing is not going to be in compliance, so there's a very strong YMMV with that.

I have a similar situation on my commute--picking my way through rutted streets and trying to assess, "will the hardpack give way and sideslip or not?" and "will the sides of that rut let me move over to the next one?"

I've found the Luxos-U running in its higher power 90 lux mode is sufficient in those conditions right up until low-speed flicker sets in at around 5 mph. Also a reason I run an auxiliary battery light.

There is no perfect system at this stage of the game--either battery or dynamo. The best you can hope for is to put together a compromise.

mrbubbles

My diy lights light up brighter at lower revolutions than my Eyc, so much for "German regulations". At my stage of the game, I don't have to compromise. I can get get battery level brightness with dynamo power without ever having to worry about the disadvantages of battery lights, namely charging them, how they function in the cold, and their limited runtime. I also never carry battery lights for short rides anymore, there's no point, I have all the lights I need.

fietsbob

Bubble is not in Germany so their lighting minimum standards are Moot ..


Eyc on my Brompton is fine.... I dont need to blind others, or descend at 50mph..

cycle_maven

I'm getting one of those 12V 6W bottle dynamos, and putting together my own lights from a Costco 5W Cree LED flashlight ($20 for 3) and some custom electronics. The flashlight head goes into an old Royce-Union headlamp with a small rechargeable battery pack, for that vintage look. It will have a USB port, too, for powering i-phones and suchlike.

RubeRad

Dude, I was willing to read your dissenting opinions and give them consideration, but then you said "breaking". I'm out.

RubeRad

I'd like to hear more about this. I'm running a cheap-azz flashlight mounted with interlocking hose clamps. I really like how bright it is (CREE XML T6, allegedly 1600 lumens, actually I don't know, but it's like a car headlight), I'm content with recharging 18650s (weekly, and I have a backup pair in the seatbag that will get me home if they fail early). I'm interested in maybe someday upgrading to dynohub, but are there super-bright CREE dynolights out there? Or starting to reach the market?

jdswitters

If you have not already found the following thread you may find it usefull. https://www.bikeforums.net/showthread...nerator-system

noglider 

I put dyno lights on one of my bikes last year, and I don't think I'm going back to battery lights except on my racing bike. I'm in the process of putting dyno lights on my other bikes. I like them much more than I thought I would, and I knew I would like them. I cannot perceive the extra drag at all. Maybe others can, but I challenge them to measure that carefully. The convenience of knowing they are going to work is fantastic. I can still mount a battery light if I'm concerned about a failure, but I've stopped doing that. The lights have proved very reliable. I get compliments on the beams they put out, too, which is pretty impressive for a 3W system.

The drag is so low (to me) that I run my lights in the daytime as well as the night. It might make me safer, and it might not, but it doesn't hurt to run them, as far as I can tell.

The drag from a sidewall generator is quite perceptible, so I only run one of those when I really need my lights.

mrbubbles

Eyc is a kind of a joke, this $50 chinese light washes the Eyc out completely on LOW mode. I've ridden with them both together.

You also tend to recommend things that are the worst bang-for-your-bucks, and what the hell is wrong with your writing style, can you compose more legibly and less cryptically.

fietsbob

Another pi**ing match ,< yawn> eat my shorts .. you are not paying for this.

cyccommute 

Let's compare apples to apples and not cheese to chalk. A "quality" battery light system that has a comparable output to dynamo systems uses rechargeable batteries that will last a very long time (2 to 5 years) and not add that much cost to the system. In today's light market, $200 doesn't just buy a lot of batteries, it buys a lot of light. Current Magic Shine clones are going for $25 per lamp. Battery packs are going for around $10 so I could buy a battery pack every year for 20 years. The realistic operational life of a hub is much less than that.

Ah, the elephant in the dynamo hub room It's also been called the "Free lunch gene". Dynamo hub people don't what to admit that you don't get something for nothing. Even when not engaged, the hubs generate some drag and it increases with speed. When engaged, the drag is significant as shown in the article that pdlamb linked to. While it is true that "good" hubs have a low drag, the drag isn't zero. At 30 km/h (18mph), the drag is the equivalent of adding a kilogram to the mass of the rider/bike. Turn the light on and that jumps to 8 to 10 W of drag according the the Bicycle Quarterly article which is the equivalent of a adding 4 kg to the bike and rider. I would suspect that the drag is independent of the rider weight so the impact on a smaller rider would a much higher percentage of the rider's power output. Another way of looking at it is that the drag will require the rider to input more effort to maintain the same speed.

Battery systems add a tiny bit of aerodynamic drag...you don't get something for nothin'...but the drag will be tiny comparably.



While I agree that light output should be in lumens or lux (only if the distance to the target is specified), with a dynamo system does have a wattage impact on the rider. A battery system does not.

Pedaleur

All pissing aside, I love how that site markets an "1800 Lumen" light when the box clearly says "1200 lumens".

Pedaleur

The only people who say this are physics-ly challenge. You make it out like you've busted some sort of conspiracy.

I guess that's what happens in religious wars...

Pedaleur

II don't think losses are that bad; maybe 5W under your scenario (~4Ohm resistance in the hub; small voltage drops across various diodes).

Getting 10W out of useful power out of a hub would be real work: 3 Crees in series at 1A -- you're definitely heading down a steep hill.

Overall, at 'typical' cruising speeds, I'm probably putting less than 10W extra into my pedals (2 Crees, Shimano hub) and getting a few hundred lumens. Definitely noticeable difference in power/speed. I could stand to have a little more light, in my opinion, so I supplement with a crappy flashlight (soon to be upgraded) and a battery-powered tail light.

cyccommute 

Back your statement up. Where am I wrong? Where is my physics wrong? A dynamo hub introduces drag into the bicycle system to produce light. The magnitude is vary slightly depending on which system you use but it is still there and it is related to the speed of the bicycle. The magnitude of the drag once the light is on falls in a fairly narrow band independent of the quality of the hub. Granted the article from Bicycle Quarterly is 10 years old but I doubt that huge advances have been made to suspend physics since then.

And this isn't about "religion" but about data that can be measured and conclusions that can be drawn from that data.

Leisesturm

I need a LOT more light than any practical dynamo system is going to be able to deliver. I suspect a lot more people are in my situation than want to admit it. I've had quality name brand lignts in the ~120+ actual lumens arena. I've seen people claim these lights are hellishly bright. I don't know but what I do know is the only two wrecks I've had were at night and they happened because I hit something I couldn't see. I'm not riding in Midtown Manhattan. I'm riding in semi-rural suburbia. There is just enough lighted infrastructure to make people think they can pull off a night commute with Nite Rider or Cygolite self contained lights. And maybe you will do it too for months until the night you whack something you didn't see and you fall right in front of someones SUV... crunch. You don't get to tell the DMV that you only drive in well lit city centers so you don't need to spend out for pricey DOT spec headlights. Even if you never drive at night your car better have two of whatever the manufacturer put in the front corners of your vehicle and at least bi-annually you are required to prove to an authority that they actually work. Truthfully, its not even the issue as to whether dyno lights work or not. The issue is that they cannot, in their present level of performance, serve as the sole source light source for a hardcore commuter. So why bother with them at all?

H

RubeRad

mrbubbles

Everyone here who is anti-dynamo clearly has never ridden a good really bright modern dynamo setup. The gungho dynamo oldies here also have clearly never used any of the newer $50 dual xml lights when they tout how awesome their german regulated dynamo setups are. (german regulated dynamo setups aren't that good)

tarwheel 

I think it would be cool to have a dynamo light system, but it just doesn't make sense in my circumstances. I have 4 different bikes that I regularly commute on. Setting up the wiring and lights on all of those bikes would be expensive and a hassle. I would have to swap my dynamo wheel among bikes or buy multiple wheels. My LED rechargeable light cost about $100 and puts out all of the light I need, and I can easily swap it between bikes. It takes minimal effort to recharge. It weighs next to nothing (100 g). My commute route is also very hilly and long, and the additional weight and effort of a dynamo system would surely slow me down.

noglider 

cyccommute, I guess I'm a dynamo hub person by your definition, however I do admit that there's no newtons. I never implied otherwise.

And the amount of drag doesn't make a difference to me, but of course if you measure it, there will be a difference. I just can't feel it. Mine is a Sanyo, if that means anything in the conversation.

Anyway, you've often listed reasons you like battery lights. I understand them, and I understand they work for you. Dynamo lights are better for me. You're cool with that, right?

unterhausen

This is clearly false. I ride long distances at night and happily descend mountains at high speed with my dyno lights. I can't imagine needing more light than a Luxos U puts out. Even my Supernova asymmetric lights do fine. The Luxos has a wider beam, so it makes curvy mountain descents easier because you don't have to worry what's off to the side. I think the only reason that I have wished I had a battery light was on a long climb when I was worn out. Actually, I was too worn out to turn on my battery backup.

Putting on my moderator hat, this discussion is way too bitter for the subject at hand. Please tone it down a little.

cyccommute 

I have no problem with dynamo lights...for other people. But people say all the time that there is little to no drag caused by them which is patently untrue. Adding the equivalent of 4 kg of mass is significant in a sport where even normal people agonize over grams.