Tail Lights and Auto Settings

What do you think of using bicycle lighting with automatic sensory settings? Several of our bikes are equipped with lighting systems that allow for this, but I have mixed feelings about the auto-mode.

Last week the Co-Habitant installed the Spanniga Pixeo tail light on his bike (very thorough review of this light here) and set it on auto. Cycling together later that evening, I switched my own lights on when dusk fell. As I rode behind him, his Pixeo tail light would switch on and off in response to slight changes in lighting conditions. For example, as we entered a stretch of road with fewer trees, it would switch off; then on again when the trees became more dense. Not only did I find this annoying while cycling behind someone, but I was also surprised that the light did not "think" it was dark enough to just stay on the entire time. It wasn't quite pitch black, but getting there. I wonder how the settings are configured, and whether they can be adjusted.

I have an auto ("senso") feature on my Busch & Mueller dynamo lighting as well, that I sometimes use and sometimes do not. Because this system includes a headlight, I can tell whether the auto mode is performing the way I want it to. If it gets dark but my headlight does not automatically turn on (which means the tail light is not on either), I will just switch it to the permanent "on" position. With a battery-operated tail light like the Pixeo and others, there is no way to get this feedback. Since you can't see you own tail light while cycling, you have to be confident that its "idea" of when's dark enough is the same as yours. For me that is not always the case with the lighting I've tried, which is why I am not that crazy about auto settings. What has been your experience?


  1. With dynamo-powered lights, I just leave them on "on" all the time, day and night - I figure, why not? They're not bright enough to be obnoxious in the daytime, and then I just never have to think about it. I don't have any battery-powered lights that have that detection, so I obviously have to turn them on manually when I think it's dark enough :)

  2. Auto settings strike me as a marketing-driven, as opposed to user-driven, "innovation". The R&D and additional materials required drive up the cost (and possibly the profit margin), and more importantly give people who already have a functional light a reason to buy a new one.

    In the end we get a light that costs more and does a mediocre job of predicting when we most likely want it to be on. All for the purpose of saving us the terrible trouble of deciding for ourself and operating a simple button. I'll pass.

  3. Do not have such fancy lights, but if I ride in an area (or in the dark) where I really need to trust the lights I always use two of each, front and rear..

  4. badmother - I think it's becoming the standard now, rather than fancy. The Spanniga Pixeo tail light can be bought for under $20, which is very cheap for bicycle lighting by US standards.

  5. I have auto on my front light (B&M Lumotec Retro) which controls my tail light (B&M D Toplight) too, so I know if it is doing that "on-off-on" thing. I don't find it too annoying, aminl;y because they come on earlier than I would manually turn them on when it is growing darker. I can always over-ride the auto whilst riding if I need to. What is more annoying is that the position of the sensor catches car headlights more easily than I'd like, due to it being German and me riding on the left in the UK.

    On the Brompton, I have a bottle dynamo version of the Lumotec Lyt paired with the Brompton dynamo rear light running constantly from a hub. The drag is imperceptible for the type of riding I do, the light is always on, so I never forget to switch them on at night. The lights themselves are LEDs, so can take being on all the time. Plus the bottle dynamo version of the Lyt was a few pounds cheaper too. Eventually I'll probably switch to an LED on the DL-1 and do the same.

  6. Velouria, I think the Pixeos might vary in their light sensitivity and may not have perfect calibration-- the one I installed on Mrs. S's mixte comes on before dusk and doesn't toggle too often... a little bit, but not much. I am eager to compare it to the two additional Pixeos I bought for some other bikes.

    If I find that they don't behave as nicely as the one on Mrs. S's bike, I'll probably just use them in manual mode.

    Daniel M-- I don't believe it's all marketing, at least in the case of the Pixeo. Spanninga offers the consumer the choice of three models: dyno powered, manual on/off, or auto with on/off manual override. I see it more as a choice for the consumer. It's not like they're discontinuing the manual versions and forcing us to choose products that take control away from us.

    And, R&D, in general, improves the breed.

  7. Automatic light? ummm....NO! I want to be 100% sure my lights are on when I wanna'm on.

    I also have many issues with the dinky butt worthless "bicycle" lights that are sold today.

    THIS is a real tail light that can be seen from a long, long way off............

  8. How does the Pixeo xb compare to the Fenderbot in brightness?
    I'm using Fenderbots on 2 different bikes and switching between a dynohub wheel + B&M light on the front (one is the spring/summer bike the other is the cold/winter bike). This just seemed to really simplify the wiring. FWIW, I also often use a second set of battery powered blinkies as backup.

  9. The jury is still out for me on the automatic setting lights. If they work well, I don't mind paying a bit more. However, if they are flaky I can do without the automatic setting and just order the manual ones. Glad you're doing this subject now. Hearing everyones experience will help me to decide what to order.

  10. I've never used one, but I don't think I'd want one. I'd be very concerned if it wasn't particularly dark but I was, for instance, riding in fog. I'd want to know they were on!

  11. I just leave mine on all the time. Does it make a difference in pedaling?

  12. I have the same B&M IQ Cyo (as well as an IQ Fly) and am generally happy with the auto settings. It seemed to work slightly better with the Fly, FWIW. Most of the time I leave it on auto and it works reasonably well; sometimes in situations like bright fog I'll just reach down and turn the light on manually. It's not that big of a deal either way. That said, i'd love a user-adjustable threshold sensor so the light owner could just calibrate the light to what worked for him or her.

  13. Jon Webb - Supposedly, there is resistance/drag. But with the better hubs it's less notable than others. Personally I cannot feel the difference even with the cheaper hubs and bottles, but maybe I am not sensitive enough to this.

  14. Walt - Wowsers, is that light as huge as the pictures make it seem?

  15. I think it comes with a trailer which you pull behind your bike.

  16. The auto sensor setting is a good option for use during the day, in case you encounter a dark stretch, say a tunnel. As the sun starts setting, I switch mine over to "on."

  17. With a decent dynamo hub, is there any real disadvantage to just leaving them on all the time?

  18. I have an edelux with the auto feature and a B&M without; I far prefer the Edelux auto; it comes on in fairly bright light (though if someone were riding behind me, yeah the flicker might be annoying, but perhaps no more than a flashing planet bike light). Because the Edelux is mounted under my handlebar bag I think it always thinks it's darker than it actually is, so it comes on more often than I'd turn it on (on an overcast day on a wooded lane, for instance). The Baucsh & Muller...I notice that my mind wanders to..."should I turn it on now? should I turn it on now?" and because it's hooked up to a hub wherein the drag is completely noticable, I delay until later than I probably should. No conclusion, just data (though were I to do it again, I'd get a 2nd schmidt and edelux instead of the b&m / shimano).

  19. I have a "senso" IQ CYO, which I justleave in the "on"(1) setting all the time. I have found the "senso" (S) setting to be unreliable. Others have mentioned just leaving the dynamo lights on all the time, and asked about any disadvantages. While that's what I generally do, i guess the drawback is that the LED only has so many hours of usable life, and you're needlessly wasting it. However, the life of a good LED is something like a bajillion hours anyway, so...

    Walt D's giant tail-light seems visible, but it won't run off a dynamo and it prolly eats double As at an alarming rate. I'd think it's overkill, unless you live ina rural area and ride at night.

    Just a small nit to pick: there is no "a" in Busch & Muller.


  20. "there is no "a" in Busch & Muller. "

    Oops. Corrected : )

  21. You can't leave halogen lights on all time time.

    1. headlight bulb has a limited on lifetime (so many hours) and it gets dimmer as it gets toward the end of its lifecycle--this is less of an issue with your tail light; and

    2. front headlight may burn out without you noticing during the day, whereupon manufacturers warn that the taillight will be damaged by overvoltage or something like that.

    If you have LED head+taillight, none of this nonsense applies to you.

    I leave my Pashley's E3 head+taillight on all the time. In addition, my fender has the Pixeo on auto mode. So I am ready for anything. :)

  22. I have a Spanninga Plateo rear-rack light. It also has the auto-on sensor, but it doesn't seem to be as sensitive as what you have described. I like the fact that it comes on automatically (as I sometimes forget to turn rear lights on), but another feature that I like is that it turns off automatically if it doesn't sense movement after a while.

  23. With an automated battery-powered tail light, I might be concerned about detecting drained batteries.

    On another note, I wonder if it's programmed like a thermostat, with two different light-level thresholds -- one for turning on and one for turning off. It would be an interesting algorithm to program.

  24. Ahh, the joys of hub powered LED lighting! I just leave them on all the time, and damn the marginal increase in rolling resistance. I can't believe it's significant on a bike of Gilbert's um, stature.

    Halogen lights and tire driven models are obviously a different story, but LED's are definitely the wave of the future.

  25. LEDs are what I had in mind when I asked about leaving them on all the time. I'm more familiar with older systems using incandescent (halogen and more primitive) bulbs with bottle dynamos, which have their own well-documented pros and cons, but wasn't sure if a hub dynamo with LED lamps would really cause any problems with daily use in the "always on" position.
    While my "see where I'm going" headlight is battery powered, I do have induction powered axle lights (Origin 8 Magna-Lites, which are less expensive knockoffs of Reelights), which flash day or night, whenever my wheels are in motion.

  26. "another feature that I like is that it turns off automatically if it doesn't sense movement after a while."

    Yup, this light does that too. Though MDI says it also turns off when cars' headlights are on it for too long - like standing in traffic!

  27. I haven't used auto lights on any of my bikes yet, but am all for anything that facilitates making cycling a 'grab it and go' proposition. Auto lights might help with this, and since this (and I'd guess most others) have an 'on' over-ride of the auto function, it would be worth it to me to pay a few extra bucks to have auto.

    I wonder how well the nut / bolt that protrudes through the fender will last. It would have to be fasted securely and perhaps loc-tited in place to make sure the light doesn't fall off. There could be tire clearance issues on tight fender installations.

    Anyone have any idea how long batteries last in LED tail lights? I've been using a couple of those Planet Bike tail lights and they seem to last a very long time. Not having to change batteries all the time is a very good thing.

    Does the light look good on the bike? In the photos, it looks nicely integrated, but perhaps a bit big.

  28. wow... is there is front version of that giant foxfire light? I've seriously considered mounting my 3x D cell Maglight to the front of my bike, weight be dammed.

    I have two back lights, the normal dynamo and a normal LED battery one as back up. I don't know if I'd want to go with complicated lights with auto features. Stuff like that gets stolen too easy.

    I like super simple. Yesterday I had to replace my 30 year old dynamo with a new Axa one... and wow.. stuff is a lot brighter now! Going to an Axa is all the technology jump I can handle :P

  29. I do not have them - I think the newest bulb in any of my current lighting systems goes back at least as far as the 1980s - but the inconsistent sensitivity would drive me nuts, and I'd just keep them in the "on" setting.
    When I'm riding in traffic and dealing with the glare of headlights, I don't want to be spending any brainpower worrying about whether *my* lights are on...

    Corey K

  30. Matt & MDI,

    Agreed that if you want to leave your lights on, you need LEDs. But, there is one bad thing about leaving LEDs on all the time. LEDs don't burn out in a flash of glory at the end of their lifespan, rather, their lumen output decreases very gradually and steadily over time. This is really difficult to notice since it happens so slowly.

    If you cycle 3 hours a day but only 1 of those is in the dark, keeping your lights on all the time will deteriorate the lumen output of your LEDs 3x faster than if you switched them on only when you needed them. Maybe the difference between a diode being useful for 10 years versus 30 is a moot point since the fixture would probably break before the LED. Oh well. I guess it really doesn't matter. But if you want the brightest LEDs on the block, only use them when you need them!

  31. Sorry, Don't want to go off topic, but the conversation of rear lights reminds me of this. I am sure it's very different in places like Boston, New york and Chicago where motorists are accustomed to bicycles and bike lights and I am sure it's better here in Texas now that bikes are growing in popularity, BUT there was a time not that long ago when my feelings towards having blinkity lights were somewhat conflicted. There were many times when I felt like having a rear light drew more attention to me then I wanted! Blinkity lights attract drunks and trouble makers like moths to a bulb, Many times when riding my bike on Friday or Saturday nights I would turn the rear light OFF, stay off the busy roads and move more in a stealth mode! Car coming? pop up on the sidewalk or simply pull well off the road entirely if that was my best option. Not sure if you or any others experience this kind of thing! At one time I had some of those valve cap lights, holy cow! Yeah, people saw me! Everybody saw me! it was like having a big flashing arrow over your head saying "look here, a guy on a bike" hardly a car would pass without saying something! Needless to say I took them off pronto!! I just got a new blinky for the rack of my new bike and jeez, it's got like 4 or 5 flashing patterns and it's big and bright! My immeadiate reaction was whoa! that may be too much light!!


  32. I love the auto setting. It's pretty neat IMO : The light goes on event during the day if i ride under a bridge, and I don't have to worry about forgeting to switch them on when the night comes.
    Since my (dyno powered B&M) front and rear lights have a "standlicht" feature, the on/off switching you describe is a non issue : The rear light stays on several minutes after the dynamo has stopped, or when the ambient light gets too bright for the sensor.

  33. I think the biggest Problem with a battery powered version with auto on/off sensor that I would forget to check if the battery is still good. With a manual switch I would see if its dead the moment I try to turn it on.
    Maybe that's only me , and because I prefer Dynopower on my everyday bikes

  34. Re: battery running out--you see it come on nice and bright when you touch the bike, whether it is to unlock or carry downstairs. If the battery is near dead, you will see it come on very dim and be clued in that it's time to replace.

    I seem to recall it's rated for 150 hrs continuously on. So, if you cycle for 1 hour every day in the dark, you'll need to replace it in 5 months.

  35. "Velouria said...
    Walt - Wowsers, is that light as huge as the pictures make it seem?"

    Yep, it's big!! This light is designed as a multiple use light since it has not only bike mounts but also magnetic mount.

    This light can be run off, full on or flashing since it is switched.

    I've seen cyclist both at night & day that run the dinky bike lights and have to say that I didn't see them until I was right on them!! We rigged up a bigger light were I retired from for a fella that had to ride at night on a two lane road in the country where it gets DARK! Before the home made light he was all but invisible after the HM light I could see him a long way back.

    That proved to me that not only is candle power important but size is VERY important to amplify the candle power.

  36. "Rona said...
    wow... is there is front version of that giant foxfire light? I've seriously considered mounting my 3x D cell Maglight to the front of my bike, weight be dammed."

    For the flashlight.........

    Yes, there is an amber version of this light that can be used at the front. (Also at amazon)

    I have one on my bike in place of a headlight since I don't ride at night anymore. Both are bright enough to get the attention of all driver I've encountered.

  37. "Walt D's giant tail-light seems visible, but it won't run off a dynamo and it prolly eats double As at an alarming rate. I'd think it's overkill, unless you live ina rural area and ride at night."

    Each to his/her own but what is the price of your life? A few batteries?

  38. Dynamo powered Edelux in front that switches a rear taillight, both with standlights. I leave the Edelux set to "auto" almost all the time, but turn it "on" for fog. I love the auto-setting. The Edelux sensor is aimed down toward the ground so isn't fooled by headlights. I'm glad it turns on in underpasses, tunnels, etc.

    Battery powered taillight B&M 4D Toplight Senso Multi in the back, too, set to auto all the time. It makes the decisions a bit differently than the Edelux in front, but I find that at least one of the taillights is on whenever it is useful. Generally, the Edelux decides to turn on first, which is fine.

    The B&M has an indicator light on the top that is supposed to go out when the battery is low. I check it after parking at night while it is still on for the standlight.

    If a headlight is so close that it is causing the light to turn off, I'm guessing that I'm pretty well illuminated by that headlight. Right?


  39. @WaltD- Squeee! You can get it in white and green too (the blue is reserved for cops) from www.columbussupply.com They are 38.00 in white :D

    Thanks for the info about the Wald flashlight mount too. I'm thinking a terralux 140 lumen upgrade on my maglite will do awesome since I already own the maglite...then I'll have a really long lasting light that will be perfect on camptours.

    You guys rawk for info!!!

  40. I use the B&M Lumotce IQ Cyo, IQ Fly and the Lyt. The Cyo and Fly are senso. I typically leave them in the automatic mode. I live in a country setting with low ambient lighting. I have not noticed an issue with headlights affecting the settings. I use a variety of tail lights with all of them being wired to the head light for control purposes. I also use PB Superflashes as a secondary/backup light.
    I like the sensor feature, in fact I quite often get in the car and can't figure out why the headlights aren't coming on :P



Post a Comment