Fenix 5 + Elite Turbo Muin B+ trainer = inaccurate speed from speed/cadence sensory

As in title, I have Fenix 5 and Elite Turbo Muin B+.

This turbo trainer has power meter + speed/cadence sensor, unfortunately when speed/cadence sensor is connected I am getting way too high speeds and inaccurate distance. (when cranking with hand I am getting like > 100kmh).

Anyone had same issue ? How to setup this sensor ? Perhaps I should change the size of a wheel to get accurate speed ?

I would like to use Fenix 5 to track all my indoor sessions for Garmin Connect (mainly for extra metrics like Vo2max, training load etc.).

Maybe I should buy external cadence sensor. Would then fenix 5 calculate the speed + distance based on just cadence sensor attached to a bike?

Interesting is fact that all other software is calculating speed as it should (based on power / cadence)

0 patrick.arce over 4 years ago

Same issue for me. Did you find how to setup the sensor with your garmin fenix?

0 Tony_Wenlock over 4 years ago

I have similar issue. I use a Tacx Turbo and set up sessions using the Tacx Desktop app. The turbo emits Bluetooth and Ant+ signals. My bike is fitted with a Garmin speed and cadence sensors which emit Ant +. I Use the Bluetooth feed for Power on he Taxc app and Ant+ from my Garmin sensors for speed and cadence. The app tracks speed and cadence correctly. However, I also track the turbo sessions on my Fenix 5 and although the Power readings are the same as the app I consistently get readings at 150% higher for Speed and Cadence (and by default the distance is also way up as well. This is simply because my Fenix is reading both the Ant+ signals. Now the killer, you can't do anything about it. You can't instruct the Fenix to ignore one of the feeds and you can't tell the Tacx turbo to not send Ant+ signals.

0 patrick.arce over 4 years ago in reply to Tony_Wenlock

I think I've found the solution. I read on my Elite turno manual that for some device, you need to divide the rear wheel circumfere by a coefficient. For example, for a rear wheel of 2095 cm, you need to devide 2095 by 15,34. So you have to set on the sensor settings, in your garmin fenix watch 137 cm instead of 2095.

But even with 15,34 it was a bit low so I adjusted by myself the rear wheel circumference in order to obtain a speed that I used to have when I ride my bike on the road with the same power and cadence.

0 Jarek K. over 4 years ago

Take a look at this manual on Elite site: elitesrl.zendesk.com/.../360001046434-Speed-value-configuration-with-MyETraining-and-third-party-apps

0 Tony_Wenlock over 4 years ago in reply to Jarek K.

Thanks for this. I've read the article and checked out the equivalent Elite turbo against my Tacx Vortex. (So many variations!!) It looks as though the speed (and therefore distance) is related to the drum size of the Tacx turbo and a calculation linked to its radial velocity. (The give away is that the use Pi in the equations). I've also had a reply suggesting that I divide my actual wheel circumference by 1.57 which is roughly Pi/2. and as an aside was also the answer to lots of questions my old professor used to set 46 years ago when I was studying telecommunications principles. Just goes to show that what goes around comes around.

0 Tony_Wenlock over 4 years ago in reply to patrick.arce

Thankyou Patrick. Will be tinkering with my watch settings. What circumference did you settle on?

0 Tony_Wenlock over 4 years ago in reply to Tony_Wenlock

Thanks again Patrick. I adjusted my watch for a turbo ride today and it has worked. MIne is a Tacx trainer so I had to tinker with the adjustment factor until it matched the reading on the app but it's all good now.

0 patrick.arce over 4 years ago in reply to Tony_Wenlock

You're welcome. My rear wheel is 2115 cm and I set 175 cm on my garmin fenix watch so a 12,085 coefficient