Charge 5 heart rate low when biking outdoors

[chippy9]

My Charge 5 heart rate seems pretty accurate during activities including indoor cycling but is consistently low when riding a bike outdoors. I tested this against a chest heart rate monitor (very accurate) and it was way off - avg was about 30 bpm lower. This has been true on multiple rides. I have loosened it and tightened it. Moved it up my wrist and down. No change.

[SunsetRunner]

I remember i read a review by DCrainnmaker that when you use GPS the HR is wrong and viceversa. You can't have both right. But this can't be true, i can't believe Fitbit made such mistake.

[DavideFitbit]

Welcome to the Community forums, @chippy9.  

Thank you for sharing this information about the inconvenience you've been experiencing with your Charge 5 and that you already tried to move it up and down on your wrist. 

Before considering other options, I recommend that you try restarting the device again using the three pulse restart method mentioned here below, instead of the restart option found on the Charge 5 itself: 

1. Connect your device to the charging cable. For instructions, see How do I charge my Fitbit device?
2. Press the button located on the flat end of the charger 3 times, pausing for 1 second between presses. Then wait 10 seconds or until the Fitbit logo appears.

In addition, please follow the instructions in this article to improve the accuracy of heart rate information and check the information mentioned here about other factors that could affect your heart rate reading, this has been useful to other users who have experienced something similar. 

Hope this helps, I'll be around. 

[Rogus]

Yes that was part of his review.  I recall he went on to say that you can't accurately track both HR and use the internal Fitbit GPS.  However, you can use your phone GPS without it causing the HR to be inaccurate.  

[DavideFitbit]

Welcome to the Community forums, @Rogus. 

Thank you for taking the time to share your feedback and experienced about this as well. The team of developers continues to work to improve the quality of products and services and all user comments are greatly appreciated. 

Have a good day.