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aviration 02-16-10 01:56 AM

New Type of Bicycle Tail Light
I've been designing a new type of bicycle tail light to solve some of the annoyances I have with existing tail lights. I'm thinking of taking the device to market, but before I do, I'm trying to gauge whether or not there would be interest in it. I've talked to a number of people locally, but am interested in getting a broader view. I've put together a short 9 question survey if anyone is interested in providing feedback. It is available at

I'd also be happy to discuss the light here. The key idea behind it is to remove the need for someone to have to remember to turn their tail light on or off. For instance if some has their light on and forgets to turn it off when they stop riding. This has happened to me on a couple of occasions and I end up burning through a set of batteries when it does. Instead this light automatically turns on and off based on external light conditions and whether or not the bicycle is being used. The light can also come in handy if you ride around dawn or dusk or through terrain where the light levels vary (mountains, terrain, rain etc). That way you don't have to pay close attention to the conditions and remember to reach back and turn the light on/off as needed.

As an added feature, I've developed a way to keep the brightness constant brightness over the life of the batteries. This was after having a number of conversations with people on group rides about whether or not people's lights were dim enough yet to warrant replacement. I really don't like the idea of riding with a light that works, but might be a little too dim to catch a driver's eye. With the light I'm working on, if it gets to dim, it lets you know.

Would anyone be interested in such a tail light?


Fl Randonneur 02-16-10 08:01 AM

Interesting concept. The headlight I'm currently using comes on automatically in low light conditions and turns off in full daylight but it is dyno powered. I would be interested in a tail light that does the same and is powered off the front hub. Any thoughts of putting together something like that?

ItsJustMe 02-16-10 11:21 AM

Hopefully you didn't spend much time developing a way to keep the brightness constant; that's a solved problem (boost regulation). As for the auto-on - accelerometer, or wheel rotation sensor? Former is easier to install, latter is cheaper.

BSB 02-16-10 05:18 PM

Make sure it stays on for a few minutes after the bike stops, so it doesn't go out when stopped at red lights.

Goca 02-16-10 09:07 PM

I would be willing to try such a light. Sounds like it has possibilities. Good luck and keep us advised.

aviration 02-16-10 11:22 PM

Thanks for the responses.

Fl Randonneur, I'm going to look into how hard it would be to create an adapter for a dyno. It might be pretty easy to do.

ItsJustMe, I did things a little differently than what you describe (primarily to conserve power as much as possible). However, I definitely started with a lot of the technology you reference.

BSB, thanks for the tip. I do have a timeout that keeps the device on for a couple of minutes after the bike stops.

Goca, thanks for the feedback. It's still a little ways out, but I'll keep you posted.

znomit 02-17-10 02:12 AM

I've seen a few references to this cateye light which turns itself on too. I thought it was japanese market only.

Regarding constant brightness... the dimming as the batteries run down is a good indicator that its time to change the batteries. You'll need another way to let people know their batteries are running low.

Juha 02-17-10 03:45 AM

B&M have several options for a dynamo operated rear light with a light sensor. They switch on in underpasses, for example. The sensors usually come with built in delay feature, so a passing ambient light source in the night (car, for example) will not cause the light to switch off.

The problem with light sensors is, sometimes it would be preferrable to keep the light on even in daylight. Some of the B&M front lights have a power switch to let you choose whether the light is permanently on, permanently off or automatic (off/on as needed). Not sure about their rear lights.


rm -rf 02-17-10 05:22 AM

I use rechargeable AAAs in my Superflash. I often leave it on, even in bright sunlight, so I show up when riding through shaded forest.

I like the constant brightness of my headlight, but it has a fairly short warning period that the batteries are running low. How would I see a warning that the taillight only has a short runtime left?

AdamDZ 02-17-10 06:01 AM

The automatic on/off feature is unimportant to me but a battery level indicator would be nice. However, my main issues with tail lights are with their construction, most are plenty bright and battery life is adequate: crappy, flimsy mounting systems, "snap-on" battery covers that fall apart or loose water seal after being opened a few times. I like the cover to be screwed on with bolts.


ItsJustMe 02-17-10 10:15 AM


Originally Posted by rm -rf (Post 10414450)
I use rechargeable AAAs in my Superflash. I often leave it on, even in bright sunlight, so I show up when riding through shaded forest.

I like the constant brightness of my headlight, but it has a fairly short warning period that the batteries are running low. How would I see a warning that the taillight only has a short runtime left?

The superflash is super-stingy on batteries. I found that the main problem was that the batteries self-discharged and in a month or so they were dead whether I used the light or not.

I've now switched to low-self-discharge rechargable AAA cells, and even after a month's use, they're only about 1/2 empty according to my charger.

DallasSoxFan 02-17-10 02:00 PM

Honestly, I don't need fancy sensors to shut my light off for me. I have a 20 minute commute and my weekend rides are about 2 hours. Put 4 "on" buttons on the thing (30 min, 1 hr, 2 hr, infinity) and that would be more than adequate for most forgetful types.

Bright and cheap sell me. Not having to cycle through to turn on/off is also huge.

My ideal tail light would be a 1W led, super bright, with a built in reflector. one slide switch for the 4 "times", one slide switch for the "mode" (flash, snazzy flash, constant), and a big, easy on/off button. The slides would almost never be touched and I'd only have to ever worry about one button.

khearn 02-17-10 04:43 PM

I don't like the timer idea for a taillight. If you get delayed, such as a flat tire, your timer might run out before you get home. And given that it's a taillight, you're unlikely to notice. I don't want a "feature" that might have me riding at night with no taillight and not even know it.

I never have any trouble remembering to turn off my taillight at the end of a ride, because my bike gets stored in my basement, which is dark enough that I notice the light.


AdamDZ 02-17-10 05:08 PM

Yeah, when I come to think of it I'm actually against any timers and auto on/off features. I never forget to turn my lights off, I carry a spare battery so no big deal. These features would add unnecessary cost. I'm also afraid those would fail quickly rendering the light useless. So for me the most important would be, in no particular order:

- bright
- waterproof
- physically rugged, both the light and the mount
- not ridiculously overpriced
- AAA or AA batteries, no coin batteries, that's a big NO for me.

I'll can get away without the following if that would mean a significant drop in price:

- multiple modes (steady and one flash mode is enough)
- battery indicator
- battery saving/brightness maintaining electronics


willtsmith_nwi 02-21-10 08:47 PM

An accelerometer will add unnecessary costs. Current regulation is a great feature. But If you're using a capacitor to produce the "pop" I don't think you would need it.

Look at the PBSF and Radbot 1000. Make them better. Incorporate some of the coolness of the Mars 4.0. Maybe run it off a oriented sideways for a more better runtime and lithium rechargeable capability.

aviration 02-23-10 01:04 AM

Thanks for the feedback and insight from those that responded. I know the light wouldn't be for everyone, but If I pursue it I'd like to address many of the concerns people might have with it. Changing flat tires, desire to use in lighted areas etc are all good points. I also appreciate the pointers to other lights.

Metzinger 02-23-10 02:40 AM

Many new bikes over here already feature a rear LED that's accelerometer/motion-sensor switched.
I don't know who makes the units. They typically attach to the trailing edge of rear racks.
One negative aspect is that they tend to turn themselves off after a long stretch of smooth pavement.
Here's an after-market one which claims battery/dynamo as power source:
Hub and bottle dynamos dominate the market here for front light systems.

Metzinger 02-23-10 04:47 AM

Here are some more:

Digital_Cowboy 02-24-10 12:24 PM

I would like to see a light, be it a headlight or a taillight that incorporates an alarm system with maybe a keyless remote to activate the alarm system.

* Super bright LEDs
* Reflectors on the back, and sides
* LEDs on not only the back but the sides as well
* Steady, and at least one flashing mode, and/or a combination steady/flash mode
* Reasonably priced
* AA, AAA, or 2032 or R14 batteries. I have two of the Serfas Guppy headlights that run on a pair of 2032 batteries and get excellent runtime out of them. I also have a Topeak taillight that runs on two R14 batteries and again I get excellent runtime out of them.
* Ruggedized both the light and the mount, that's the only complaint I have with the mount that Topeak made for my pannier rack. After removing my taillight a couple of times the loop broke off.
* Weather/waterproof, an O-Ring that doesn't come off and gets lost easily

2manybikes 02-24-10 12:55 PM

The ideas are great, but the difficult part might be building it cheap enough. Get some good market research before you spend too much money on the project. Sure you can build it, but they may not sell. Lack of market research is very common with inventors. Even if something is a good idea, it may not sell well enough to recover investments in making it. Even if something is patented, it still may not sell.
I personally would pay a relatively high price for one that worked very well. But I don't know of anyone local that would. I see a lot of riders in the summer when ocasionally running, or working at, a couple of bike shops around here when the owners are not around.
Most people at the bikes shops around here would not even spend $19.95 for a PB Superflash. Most cyclists do not ride at night and think that the price of an accessory should be much less. More like $10 or less.

BearSquirrel 02-25-10 01:52 PM


Originally Posted by 2manybikes (Post 10445768)
Most people at the bikes shops around here would not even spend $19.95 for a PB Superflash. Most cyclists do not ride at night and think that the price of an accessory should be much less. More like $10 or less.

This is an excellent point. Most shops would rather sell a $3 blinkie for $17 than a $17 blinkie for $30 like the PBSF. True bicycle fanatics are a rare breed and so the cost of good electronics will remain high until we get more people "in the tribe".

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