Front light turning off bike computer

I have an old school sigma computer on my bike with a wheel magnet. When I use a flashing front light it stops the computer from working unless I put the light somewhere near my brake lever. Anyone else get this and is there way round it.

Comments

  • It's fairly common for LED lights to interfere with wireless bike computers. All you can do without changing either computer or light is to position the computer as close to the wheel sensor and the light as far from the computer as is possible.

    The cheaper end of wireless cycle computers send current through a coil in the sensor every time the magnet goes past, generating a magnetic field that the computer detects. A flashing bike light sends current down the wire to the LED each time the light flashes, also generating a weak magnetic field. Depending on the computer, it may give a wildly incorrect speed, or just turn off because something's obviously wrong.

    Setting the light to steady generally won't help as most modes are a very quick flash, with the LED actually off part of the time.

    The general solution is to use a wired cycle computer rather than a wireless one.

  • Webboo2
    Webboo2 Posts: 393

    Cheers for the info. Do flashing lights effect Garmin type computers.

  • whyamihere
    whyamihere Posts: 7,702

    No. Even if you use one with a speed or cadence sensor, they'll pair using something like ANT+ which won't be affected by the light in the same way.

  • Charlie_Croker
    Charlie_Croker Posts: 1,699

    ...and if you get the right lights you can control them from the Garmin. I have a pair pf Bontrager's I do just that with





    😀

  • pinno
    pinno Posts: 51,353

    I have a rear wheel fitting for my basic compooter pick up and wheel magnet. Then I use the rear light on solid mode, not flashing.

    seanoconn - gruagach craic!
  • thistle_
    thistle_ Posts: 7,149

    If @Webboo2 is still having issues...

    A ferrite bead or two on the power cable for the light might help reduce any EMI.

    https://uk.rs-online.com/web/p/ferrite-sleeves/7740632

    You can also get bigger ones and loop the cable through a couple of times.

    Sometimes they help, sometimes they don't it depends on how the interference is getting out of the light and into the computer.

    You could "borrow" one off a USB or computer screen cable before committing to buy some.

  • Webboo2
    Webboo2 Posts: 393

    You’ve lost me there. What’s the power cable on the light.

  • pinno
    pinno Posts: 51,353

    I think Thistle isn't aware of your paraffin lamps.

    seanoconn - gruagach craic!
  • thistle_
    thistle_ Posts: 7,149

    😂

    My big lights are like this with external battery packs: https://thelazyrando.wordpress.com/2010/05/28/900-lumen-led-bike-light/ I should get with the times.

    @pinno's suggestion of paraffin lamps sounds like the best solution.

  • photonic69
    photonic69 Posts: 2,417

    I had this issue many years ago using a Cateye computer and flashing LED light. I found the flash complete killed it and the steady mode gave unreliable distance/speed readings. I bought a wired Cateye Velo 7 computer and had no trouble with that.

    You could try wrapping some silver foil around the light body to see if that provides some shielding. There are some people that swear it's very effective when fashioned into a hat.


    Sometimes. Maybe. Possibly.

  • Webboo2
    Webboo2 Posts: 393

    I found that if I put the light by the brake lever, the computer which is next to the stem still works. However I have to ride one handed if I do that. Maybe I should just buy a Garmin.