Distance discrepancies using a bike tandem

[Billybob2092]

I originally started this on the Charge2 bike forum.  We are having a consistent problem.  While riding the tandem bike tonight I did 9.7 miles.  My wife showed up as 5.04 miles.  This is a continual problem.  We tried restarting my wife’s Fitbit.  No change.  Please help.   

Moderator edit: Subject for clarity 

[RicardoFitbit]

Hello @Billybob2092 thanks for bringing this to my attention, it's a pleasure for me to help you with your distance accuracy situation. Also, I'd like to give you a warm welcome to our Community Forums.

Seems odd that you and your wife are experiencing such distance discrepancy with your Charge 2 devices, even more when performing the same activity in a bike tandem, thanks for restarting your devices prior to posting.

To better assist you with this situation, can you please let me know in which way you initiate the bike activity? Both of you are using our SmartTrack feature to auto-recognize the activity or using your Charge 2 shortcuts to track bike exercise? When was the first time this was experienced and how many times since then? Also, both of you are recording GPS data with the connected-GPS feature? Take in consideration that Charge 2 doesn't have a built-in GPS, therefore, the Fitbit will connect to your mobile devices to track data. That said, please check that your mobile device is compatible with our products and services, same for your wife. 

In the meantime I receive your answers, I recommend you to learn more about: How do I track my workouts with my Fitbit device? for more information and details about exercise tracking. Also, Does my Fitbit device have GPS? to learn more about GPS. 

Let me know if you have any additional questions, I'll be around. 

[Billybob2092]

Thanks for responding. We both have iphone7. We open our Fitbit app prior
to switching the charge2 to bike mode and holding the button in to start
the ride Tonight we had the same circumstance. We rode 1 hour and 5
minutes. Both started our phones and charge2 the same way at the same time.
I rode 10.94 miles. At an average of 10.0 mph. My wife rode 3.27 miles
2.9 mph average. Any help you could provide would be appreciated. A
L of her other gps apps work perfectly. Thanks
Bill

[Billybob2092]

I just wanted to update our situation.  We are getting significantly better results.  The difference is my wife has removed the phone from her back pocket and is keeping it in a pouch . We are generally within .1 miles of each other since the change 

[RicardoFitbit]

Hello again @Billybob2092, I appreciate the information that was shared with me, my sincere apologies for the delay in responding, it's a pleasure to continue assisting you.

Thanks for your update and the information that was posted, I'm happy to know that you and your wife are getting better results. Let me share with you that our algorithm on Fitbit devices is optimized for a single biker, which can deliver certain distance discrepancies when using a bike tandem. However, can you please let me know if your wife is the leading driver of the bike tandem? In other words, the person who's in the back sit may experience certain difficulties, therefore, can you please try sitting on the back sit of the bike tandem and let me know if you experience the same discrepancies?

Looking forward to your reply. Don't hesitate to ask me any additional questions you may have.

[Billybob2092]

My wife sits in back. She is unable to be captain. We are still getting
better results with her phone out of her pocket