Bike Light Mod: add an accelerometer

PS, yes, you do have to add code (included at the page) to it to make it work — the LightBlueBean is $30:

It does, uh, a few other things too. Not quite small enough to fit in a flashlight — yet ….

(The taillight they show is one that’s both very bright, very tricky modes, and has room behind a reflector to put in the microcontroller board)
It’s this one:

Cool find Hank. So many cool ideas. I wonder if this can transmit audio to the phone.


Just cool!

Datasheet on the bluetooth module

Sweet…it’s an Arduino board w/ built in bluetooth connectivity…awesome!

If all you wanted was a accelerometer and arduino capabilities (minus the blue tooth wireless programming of course)

A teeny accelerometer that mounts to the teensy board

Teensy board with the micro sheld on the back

Even have an OSHPark board for you

Still that is a WICKED cool project!!!

So what it gonna take to make it a brake light, (imagine if cars did not have brake lights) why should bike go without?

Anyway we could hook up an accelerometer to a flashlight to increase the output dependent on speed? Fast bike = bright light, etc

At less than half the price and just slightly larger one might consider using a MultiWii SE clone board:

It’s got a 3-axis accelerator + a 3-axis gyro and lots more IO available.

Wow…daggum…good find wight!

Flight controller module sweet! Guess it could be used to turn off and on a light

Thanks. If sensors are your thing, you can add a really rough barometric altimeter (jitters >1 meter IIRC) and a perfectly good 3-axis compass for a couple dollars more… but you lose the handy USB interface and must use either a FTDI style interface.

For this project I think my other link makes the most sense: it comes with the headers unpopulated, which saves space, and it’s got USB built in which is handy, and it’s cheaper.

EDIT: both of the boards I linked to work fine with the Arduino environment, same as the LightBlue Bean linked in the OP.

i had an idea to build bike stop light. there is a product “lucid brake” taht is basically already made accelerometer based stop light, but their video shows it brighter that it is in video of people that bought it and used it. in reality it is not as bright.
i also found compleate how to plans on similar light on instructables

i never actually ended up buing or building one, i do not think it will make bike riding any safer, since we normaly do not have brake lights on bikes, i doubt a person riding behind will figure in time what that light is. i mean i have been rear ended in a car, with 3 brake lights on, and people aware of what those light on a car mean.

i’m sure it will be fun to build such light, but as far as practical benefit, i seriously doubt. but than i do build many things just because i want to, not because it will have practical benefit to me.

Seattle (among other cities) has a shared-bike setup, and I hear those already come with an accelerometer-triggered taillight.

And I know I’ve seen at least one commercial taillight that includes this and a “brake light” feature that makes it brighter when you slow down. I don’t recall which one tho’.

MTBR is probably the place to look for more info.

But I’m delighted to see this thread branch out with multiple different sources and ideas.

The innovativeness reminds me of an old idea from Gransee, who early on thought he would make Arc flashlights that could modulate the emitter — so you could plug in a headset on a pair of them miles apart, point them at each other, and talk over the light beam. Other stuff happened instead, sadly, and I don’t think that ever happened.


Accelerometers are cool, but what if we just used the existing brake actuators to trigger the light? This would better emulate the brake lights used on a motor vehicle. Just like on a motor vehicle, you’ll have a taillight anyway. The brake lights are not there to indicate any and all deceleration, they are just to indicate that “hey, this person is activating the brakes… they may either be rapidly slowing down or about to rapidly slow down” … that second part is at least as important as the first part IMO. Knowing that someone is lightly pressing the brake in preperation to brake harder is crucial… IMO.

when I’m driving my car, I tend to hit the 4-way-flasher button when I’m slowing down suddenly.

And — a trick I learned from a driving instructor — put my hand up in front of the rear-view mirror and wave it back and forth fast.

Drivers behind often notice that when they’re ignoring all the colored lights.

On a bicycle?

Heck, I”d like a little fireworks display I could drop behind me any time I am going to slow down …

I asked, they answered. I invited them to look in, and it sounds like they will.
So if you’d be interested in the BlueBean board, feel free to add a brief “interested in BlueBean” note.
If there’s much interest I’ll sum up and email them
(or, I suppose, you could do that directly, this will get to the support thread email I started, I think)

I’m not rushing anyone into this particular board — glad to see other suggestions coming in
(note that the BlueBean mod fits into a known, available, good bike taillight, tho’, which simplifies things)

Awesome Idea - stop at a traffic light - rear light goes off and you get crushed by a car.

> Absalom

You must be a young’un (grin).
That’s how early generator bike lights worked, a wheel rode on the side of the tire turning a generator.
No move, no light; brighter and brighter the faster the wheel turned (incandescent of course).

Good ol' Dynamo! All the new generation kids get their new fangled dynamo hubs. IIRC they are 6V dynamos, so maybe MT-G2 or XHP50? ;)

And when you went too fast the bulb blew.

Just to be clear — “stop at a traffic light – rear light goes off ” is not describing how this accelerometer board works.

He’s, I guess, mocking the old generator lights. But hey, they kept the mastodons away ….