Increase baseline resistance

[Dimitar_Marinov (Dimitar)]

Checked with nRF Connect, and I can confirm that the Tacx Flux S trainer does not support the setting of Wheel Circumference values. Not at least over bluetooth, since the FTMS bluetooth spec is relatively new (2017) there is a very slim chance that this is possible over ANT+ and just missing for BLE, but I’ll have to get to my linux machine in order to check that too, so maybe later over the weekend.

For future reference and because it still might be useful to someone I am leaving here the steps needed to set a Wheel Circumference value over bluetooth FTMS with nRF Connect for Android, (probably the same is possible with LightBlue for iOS):

1. Install from play store nRF Connect for Android

2. Start a scan
   

   

3. Connect to the device

4. Go to “Name of the device” Tab, Tacx Flux 46731 in my case

5. Select “CLIENT” from the second row of tabs, if its not already selected
   

   

6. Select Fitness Machine Service, and scroll down to Fitness Machine Control Point

7. Enable indications by clicking on the ‘up and down’ arrow icon to the right
   

   

8. Open the input popup by clicking on the ‘up’ arrow that’s next to it

9. Send Request Control message by entering 00 in the the field and click Send below
   

   

10. Swipe to the right and you should see the console buffer,

11. There you have to see the messages:

• “Request Control sent”
• and “Response for Request Control Result: Success received”
  
  

13. Now open the input popup again by clicking on the ‘up’ arrow
14. Enter a value for wheel circumference, here is a list of some useful ones:

You have to type in the value from the 3rd col. Example: enter 12F055 if your choice is 2200 mm or 700x40C.

700x25C | 2105 mm | 123A52
700x40C | 2200 mm | 12F055
700x47C | 2268 mm | 129858
Max | 2750 mm | 126C6B

Where 0x12 is the operation code, and F055 is hex for Uint16 2200*10, and 10 is just the resolution of the value. In decimal the message is [18, 240, 85].

In my case the operation is not supported and I see: “Op Code not supported”

If it is supported you should read just: “Set Wheel Circumference New Wheel Circumference: some value”.