I’ve got a Garmin 920xt and an Edge 500. On the road, the single sensor on the chain stay picks up the cadence (attached to crank) and speed (attached to spoke).
When I’m on the Tacx Neo, this becomes a problem. As there is no wheel, there is also no spoke / speed sensor for the chain stay sensor to pick up.
The Tacx Neo has its own speed sensor, but the cadence seems to be some type of algorithm that jumps all over the place, even when I’m confident that my cadence is spot on.
I would love to be able to tell my Garmin devices to use the crank sensor for cadence, and the Neo for speed, but I’m unable to work out how to accomplish this. The Edge 500 will constantly inform me that it’s located multiple spd/cad sensors, but gives me no further configuration options. If I enter each sensor’s ID manually in the “speed and cadence” section, I get cadence but not speed.
On the Forerunner 920xt, there is no such option at all. You can enable one sensor, or the other, but not both at the same time. It insists that any such item work as a single unit. The option is to activate or deactivate any detected sensor(s).
I reason the same will hold true for any direct drive trainer, so if you’ve got a technique that’s worked for you on your Kickr / Drivo / Hammer, I’d be grateful for any assistance.
Thank you very much for your help and suggestions!
I know “spend more money” was not on your list of responses, but that is what I would do if I were in your shoes. I would get the Wahoo speed & cadence bundle (http://www.wahoofitness.com/devices/speed-and-cadence-sensors-bundle#) or the Garmin version (https://buy.garmin.com/en-US/US/p/146897). I would get the Wahoo, mainly because they are Ant+ & BLE. Then, when you remove your wheel, your Garmins will not get confused. And as an added bonus, these new gen of magnet-less sensors are the total bomb.
I’m not opposed to throwing cash at the problem, but I’m not certain how your solution resolves the issue. If I mount the new magnet-free sensor to my hub, and remove the wheel… I’m still stuck with exactly the same problem, but via a different mechanism.
Maybe I should further clarify:
If I use something like TTS or Zwift, then yes - I can supply the correct cadence sensor in the software. However, I would like to simultaneously record my workouts on my Garmin devices to provide secondary sources of data for A) basis of comparison and B) redundancy in the event of a software failure on TTS / Zwift (as happened today).
With the Garmin devices, I’m able to get cadence data or speed data, but not both while I’m on the Tacx. No problem on the Kinetic Road Machine.
While I’m mainly concerned with w/kg, and the Neo does a fantastic job of gathering power data, I also want to make sure that my power / cadence / speed values are coming out where I’m expecting. Zwift produces some pretty dubious results.
The problem is that the Garmins treat the combo sensor as all or nothing. So, if you split them into independent sensors, the Garmins will always use the cadence sensor. But, when on the Tacx, the Garmins will use the Tacx for speed. When the wheel is on, it will use the wheel for speed.
Unless you know for a fact that cadence in Neo is calculated virtually, and is not in fact data fed by a sensor from inside the trainer, I doubt this is the case. It doesn’t even make sense. Anyway, I had zero issues with cadence readings on either of my two Neos.
I haven’t disassembled the unit, so you’re correct - I have no idea whether there is an internal sensor in the Neo that’s counting crank arm passes. However, given the wild variability from moment to moment, I suspect that is not the case.
Truly, riding on a 0.0 grade in the same gear, the indicated cadence would fluctuate 20-30 rpm from one rotation to the next. It defies explanation, but evidently I am not alone. Here is another thread exhibiting exactly the same problem earlier this year:
The Neo does calculate cadence rather than measure it directly (ish). In order to provide a constant power output it is constantly sampling the speed the unit is driving at. It does this so often that it can pick up the tiny variations in speed that occur as your pedals rotate through 360degrees. At 0 degrees your pedal speed is slower than at 90 degrees. It then becomes trivial to calculate the cadence.
You will have to update the firmware to the latest variant in order for it to be accurate! My new Neo had older firmware in it that was terrible for cadence when compared to a wahoo sensor. I updated the Neo and it is now spot on all the time.
You will have to update the firmware to the latest variant in order for it to be accurate! My new Neo had older firmware in it that was terrible for cadence when compared to a wahoo sensor. I updated the Neo and it is now spot on all the time.
Excellent point. The current firmware version is 0.5.1/0.2.1/0.6.11. If Ganellon is running an older version of firmware that would explain his problem.
Unfortunately, I can’t blame the issue on firmware update, as that was the first thing I did after unboxing.
Currently, mine is showing 0.5.1 / 0.2.1 / 0.6.11
Also, I have no idea why it shows three version numbers nor what they correspond to.
I’ll make a short video to demonstrate the problem with the cadence. My explanation of the issue may be inadequate for folks to visualize. It’s worth a chuckle when you see the cadence leaping all over the place.
There is a new firmware update, either from yesterday or today, 10 February.
new version: 0.6.2 / 0.2.1 / 0.7.3
Fingers crossed that this resolves the issue. I’ll test it tonight.
Thanks for the update. Just for grins you probably should have someone else pedal your bike to see if they have the same result. I can make my cadence be off if I intentionally pedal in a wonky fashion or just for an instant when transitioning from standing to sitting.
Thanks for the suggestion. We’ve tried it on two different bikes, but not two riders on the same bike – same result.
You may be correct, but I think anyone on Slowtwitch should already know what exactly 90 rpm feels like, and certainly know if they made a sudden jump to 115 or 120 (or 70 or 45). With my current setup, I’ve got TrainerRoad (Ant+) recording cadence from the magnetic sensor, and Zwift (BLE) displaying cadence data from the Neo. The Garmin sensor is more solid, and reflects my expectations based on gear ratio and slope.
I’ll know for certain tonight and post results. Thanks again for your help.