I have two heart rate monitor chest straps from Sigma and one from Garmin. Everytime I pass close by a trainline the numbers on my HR-Display go bananas. I'm about to go insane because of this, is there anything to do against this? Buy something new? Or throw it all in the bin..

  • Can you be more specific about the model of heart rate monitors you have? Do you know what communication methods they use, like ANT+, Bluetooth, or some other proprietary protocol. I used to have similar problems with an old wireless speedometer when waiting at traffic lights. But I haven't had any problems with my ANT+ HRM or speed/cadence monitors.
    – Kibbee
    Sep 20, 2016 at 12:38
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    Your problem comes from electrical interference with the heart rate sensor. If you have to have a solution, switch to a heart rate monitor that uses an optical sensor. Many of the wristwatch type heart rate monitors use optical sensors.
    – Gary E
    Sep 20, 2016 at 15:55
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    Worth noting that optical heart rate sensors are usually much less accurate than electrically based monitors. At least from what I've heard.
    – Kibbee
    Sep 20, 2016 at 16:46
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    My max is 185. And there's a world of difference between maxing out at 175 or 180 during Intervals. 175 is normal. 180 means throwing up all over my garmin and handlebars before I'm even finished.
    – AzulShiva
    Sep 20, 2016 at 18:27
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    If you hit your max while cycling you did not hit your max. You should not be able to hit your max while cycling. Ever. Unless you're suffering from hyperthermia or getting a heart attack of course, then it's justified. Your max is your absolute highest possible, if you hit your max regularly you are training waaaaaaay below your zones.
    – AzulShiva
    Sep 21, 2016 at 6:34

1 Answer 1


Hmmm... I smell a science project! If the field is really strong be aware that optical may not work either because the chips/wireless probably aren't shielded anyway. Assuming you don't need laps for training, you could try hitting your lap button so at least you know when the event happens. I suppose you could try an experiment by taping aluminum foil to your chest covering the monitor pickups but not the wireless unit. That might tell you if the shielding issue is in the leads as I suspect or in the main unit that picks up the wireless. Ask yourself if the speed/cadence monitors wireless signals are being received to indicate whether an optical monitor might work.

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