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  1. #1
    Senior Member JonnyHK's Avatar
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    Brake light with accelerometer

    http://www.bikerumor.com/2013/05/13/...ht/#more-60037

    Looks like a much more practical and reliable solution to something that folks have been tinkering with for years.

  2. #2
    Randomhead
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    I have a dyno brake light. Haven't put it on a bike yet

  3. #3
    Seņior Member ItsJustMe's Avatar
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    Seems a bit steep. Adding an accelerometer should only add maybe $8 to the cost of a brake light, and that's on one-off pricing, like if I just went to Digikey and bought a single accelerometer chip. It should interface fine to the processor that's already there in the light.
    Work: the 8 hours that separates bike rides.

  4. #4
    Engineer Indrek Rebane's Avatar
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    Velodroom bike light

    Well... as an engineer working on a similar, but less expensive and way better looking
    bike light, I can tell it is not the components that cost. Electronics add maybe 4$ to this project.
    Main expenses are probably R&D and marketing. Still, 100$ implies a bit too large contribution
    from the backers to get their production costs down. After that they may reduce the price,
    but not holding my breath for it. Just my biased opinion.

    Project I'm working on: http://vd.ee
    and a brief Velodroom trailer/teaser

  5. #5
    Senior Member JonnyHK's Avatar
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    Quote Originally Posted by Indrek Rebane View Post
    Well... as an engineer working on a similar, but less expensive and way better looking
    bike light, I can tell it is not the components that cost. Electronics add maybe 4$ to this project.
    Main expenses are probably R&D and marketing. Still, 100$ implies a bit too large contribution
    from the backers to get their production costs down. After that they may reduce the price,
    but not holding my breath for it. Just my biased opinion.

    Project I'm working on: http://vd.ee
    and a brief Velodroom trailer/teaser

    Much better looking and more practical (mount etc)..

  6. #6
    Engineer Indrek Rebane's Avatar
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    Velodroom now also covered in bikerumor: http://www.bikerumor.com/2013/05/14/...ve-bike-light/

    We are also working on front light and want to make it the best one in the world,
    so any feedback-suggestions-comments are welcome.
    Last edited by Indrek Rebane; 05-14-13 at 06:24 PM.

  7. #7
    Senior Member Aushiker's Avatar
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    Interesting and thanks for sharing. I have thought of fitting a Busch & Mueller BrakeTec as I run a dynamo on one of my bikes.



    Andrew

  8. #8
    Engineer Indrek Rebane's Avatar
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    Quote Originally Posted by Aushiker View Post
    Interesting and thanks for sharing. I have thought of fitting a Busch & Mueller BrakeTec as I run a dynamo on one of my bikes.
    Busch & Müller TOPLIGHT line brake plus is pretty good. Probably best you can get just now.
    Good engineering and ingenious operating principle. Also very reasonably priced.

    Velodroom is working on dynamo model as well, but this will not be on the market before 2014.
    Dynamo connection is currently mandatory for bike lights in Germany by StVZO TA. Of course
    we will do our best to make better light than B&M. However, if you need one now there is no
    match to B&M as far as I know. And this comes from their competitor.

  9. #9
    Senior Member
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    AIUI B&M uses a frequency comparator to detect when the bike is slowing (from the dyno hub). That seems likely to be cheaper (all electronic) than adding an accelerometer into the mix.

  10. #10
    Senior Member Looigi's Avatar
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    Quote Originally Posted by pdlamb View Post
    AIUI B&M uses a frequency comparator to detect when the bike is slowing (from the dyno hub). That seems likely to be cheaper (all electronic) than adding an accelerometer into the mix.
    Accelerometers (and gyros), as used in cell phones for example, are inexpensive solid state electronic devices.

  11. #11
    Engineer Indrek Rebane's Avatar
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    Quote Originally Posted by Looigi View Post
    Accelerometers (and gyros), as used in cell phones for example, are inexpensive solid state electronic devices.
    This is indeed so. However, electronic components are not the main
    cost in a project with low volumes. Less than 20 000 pieces, say.

  12. #12
    Senior Member skycomag's Avatar
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    I came across these http://www.ebay.com/itm/111058289337...84.m1497.l2649.

    can't beat the price. I order 2 of these to use on my bike rack to improve the brake light visibility. sinc my bike blocks my brake lights.

  13. #13
    coprolite fietsbob's Avatar
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    As the hub dynamo has Power pulses, the B&M one lights brighter as the Pulse Frequency drops .
    in normal operation there is a capacitor to smooth out the pulses

    Flashing tail lights are verboten in German bike regulations.
    but Asian Export Stuff sells withall those flashing Modes.

  14. #14
    Senior Member stbtra's Avatar
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    Quote Originally Posted by ItsJustMe View Post
    Seems a bit steep. Adding an accelerometer should only add maybe $8 to the cost of a brake light, and that's on one-off pricing, like if I just went to Digikey and bought a single accelerometer chip. It should interface fine to the processor that's already there in the light.
    99% of lights do not have a processor on them, they're mostly special purpose custom cheap silicon that can do very limited things

  15. #15
    Seņior Member ItsJustMe's Avatar
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    Quote Originally Posted by stbtra View Post
    99% of lights do not have a processor on them, they're mostly special purpose custom cheap silicon that can do very limited things
    OK, so add about 80 cents minus whatever the custom silicon costs, to the total cost. 80 cents is what I can buy small processors for in relatively small quantities (100+) In 5000 quantities, it's down to about 60 cents or less. The accelerometer is a more significant cost, they're usually a couple of bucks in the quantity I buy, but I'm sure when you start buying a few thousand the price drops considerably.
    Work: the 8 hours that separates bike rides.

  16. #16
    Engineer Indrek Rebane's Avatar
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    I'm glad to announce that things have moved a notch closer with Velodroom bike light.
    Today we are launching our Kickstarter campaign and hopefully reach our set goal.

    Kickstarter page:
    http://www.kickstarter.com/projects/velodroom/velodrooms-smart-bicycle-light

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