Milestone Foot Pod distance different to Zwift distance..


(Alex Juggins) #1

Mrs J uses a Milestone Footpod when she is running on her treadmill to allow her to Zwift and record data for Strava. There is a discrepancy between the treadmill and the Zwift distance which is not unexpected. However what does seem strange to me is that the footpod and Zwift are recording different distances and not by a small amount…1 mile different over a 5-6 mile run.  How does Zwift calculate pace/distance and what data from the pod is it using to do so? 

 


(Steve Copeland) #2

It’s two things from what I have been able to ascertain. The first is you need to calibrate the foot pod correctly. Go for a run over a known distance and then use the milestone app to correct the distance. I did mine by doing a park run but you can do it on the treadmill as will by running a fixed distance.  

The second is a bit more tricky as Zwift has a bug that I have raised a call on in that it does not record the steps per minute correctly. If you look on the spm readout I Zwift when running you will see the SPM is exactly half what it should be and to correct it Zwift have doubled the stride length. So for me I see 90 SPM when I am doing 180 and a 2.1m stride!  Upload to strava and you will see what I mean. This creates an error in the distance as well. 

Zwift have not accounted for the fact that for every impact that foot pod records it’s actually two steps (unless you are hopping on one leg…). 

 


(Alex Juggins) #3

Thanks Steve, I noticed the SPM bug before on one of her Strava logs. I also see that Zwift have recognised it and intend to fix in an upcoming update.  So that should cease to be an issue.  What confused me was that if Zwift gets it’s data from the pod, you’d think the two would be the same unless they are calculating distance from SPM and stride length but using different algorithms to work out distance/pace…?


(Steve Copeland) #4

I think it’s a combination of the calibration and the bug.  When I calibrated my pod the error between Zwift and the treadmill became smaller. Also you don’t actually cover the same distance as the treadmill because it’s ground moving under you rather than you moving over the ground.  If I run 5k on a fixed known run the error on the pod is negligible but still there onnghe treadmill. 


(Alex Juggins) #5

Yeah I expected the treadmill distance to be less than useful.  I will make sure she is full calibrated and give it another go…see what changes. 


(Steve Copeland) #6

Software update arrived this evening!  I just ran a 5km to test it and the SPM is now correct and with the treadmill set at 10kph I was reading about 10.6kph on ZWIFT which is close enough for my needs!

Good to see Zwift listening and acting quickly.

So to recap, make you calibrate your foot pod on a fixed known distance and it should be pretty close.


(Alex Juggins) #7

Ok, so this isn’t resolved.

Zwift update has been done…this has corrected the SPM as intended.

Calibration of the Milestone pod has been carried out over a measured distance and the pod resynced. 

Zwift calibration has also been carried out. 

However, the main issue has not resolved itself. During the test run after calibration we have the following data:

Footpod has recorded a distance of 1.91 miles at a pace of 10:30/mile. 166 SPM

Zwift (and therefore Strava) recorded a distance of 1.62 miles at a pace of 12:45/mile.

I’m still extremely confused about how this happens.  The ONLY measuring tool that Zwift has to determine distance/speed is the footpod. It has no other source of data other than the HRM.  How is it calculating the pace of the runner? It can’t be using the pace that the footpod transmits or surely the two figures would be the same? 


(Steve Copeland) #8

Do you have the footpod set to record run and walk?  I do see a small discrepancy but nothing that really concerns me. At the end of the day it’s just about the workout for me and using Zwift just gives me nice imagery rather than looking at the wall!


(Alex Juggins) #9

According to Milestone the pod does that itself based on the ratio of running to walking. Either way it wouldn’t explain Zwift being less than the pod.  

In her case the discrepancy is significant enough to make any data gathered via Zwift useless other than the HRM. 

It would be great to have an official response on how the pace is calculated.


(Steve Copeland) #10

I tested this on mine. In the milestone app there is a switch that tells the pod to record running only or running and walking. If I switch it to run and walk it records the warm up and creates a discrepancy between Zwift and the milestone record. If I switch it to run only the error does not seem to occur. 

I then set Zwift up on my phone and ran outside a GPS tracked route of 10km.  Zwift recorded 10.8km from the pod which was the same reading from the milestone app. So there is an error of .8km over a 10km run which for me is nothing to be concerned about. However I have corrected it in the calibration section of the pod on the milestone app so will run it again and see if it corrects. 


(Alex Juggins) #11

It seems that we have made some progress.  Some thanks to Steve Copeland and some due to pure persistence.  The process went as follows:

  1. 1km road run using Strava to record live and the Milestone.
  2. On return; calibrate the Milestone using the “Adjust” function in the Milestone app. Set the distance to the correct 1km.
  3. Re-connect Milestone pod with Zwift (including now, pace AND cadence (this hadn’t appeared before).
  4. Calibrate pace with Zwift using Spanner Icon setting treadmill to 8kmph to match Zwift.
  5. Run.

 

Over 10k the Milestone reported 11km however we know there was a warm up and a gap in the middle where Mrs J had to leave the run for unavoidable reasons.  Once the Milestone synced we were able to see a pure 10.7 which is much better. It’s also noticable that with the treadmill set to 8kmph the Zwift app was reporting pace at between 7.5 and 8.5 so in the right ball park. 

 

It certainly feels like this is a more representative record of the run.  She is happy, so I am happy.

 

Thanks for your help Steve, shame Zwift didn’t make an appearance…


(Steve Copeland) #12

You are welcome. :slight_smile: