Power output keeps dropping to zero

During the last week i have been having a very inconsistent experience while riding on “The Island”. All probably related, but would love some feedback and/or some trouble shooting tips/workarounds.

My rides previous to this week were flawless, with a very consistent experience.

They are:

  1. My power output keeps going to zero for 1 - 10 seconds at a time. My rider will dismount his bike about once every lap and the game will pause at least once every 2 laps… really annoying when it happens as I’m sprinting for green checkpoint or trying to hold someones wheel on the climb :wink:

  2. The resistance is not being consistently adjusted. During this evenings ride, for example, the resistance never changed during my 45 minute ride. Two nights ago, it was spot on, more resistance while on the climbs, less while descending.

I’m sure both are related.
I am using a Wahoo Kickr (purchased Jan 15, 2015), Newer Laptop running Windows 7 (It meets the spec), New ANT+ dongle

Steps I have taken:

  • Moved the dongle to a different USB port, uninstalled USB drivers
  • Moved the computer (Dongle) closer to the Wahoo
  • rebooted the computer, both with the Dongle in and out
  • performed the initial spin down on the Wahoo, using Wahoo app. multiple times

Am I missing something? The first couple of rides were amazing. I love the island!

Thanks in advance

So, I have experienced a similar issue:

*I am new, as in just this week and have ridden 5 times
*When I used my Surface Pro for 2 days, I did not experience any issues
*When I switched to my desktop for 3 days/rides, each ride I have experienced losing my power output for 5-7 second time periods
*I’m riding a Schwinn AC performance indoor bike with Mpower console. The console is on and reading the entire time
*The computer was right next to the bike, so it shouldn’t be a proximity issue
*I’ve made some changes, but next time it happens I want to validate that it drops the HR monitor too. If that is the case, it is more likely an issue on the computer, usb, driver, application side and not my bike/mpower console setup

OK, it happened again twice this morning. My watts and cadence both drop to zero in the middle of riding. My heart rate did not drop. I’m going to try another computer in a few days to try and isolate the issue.

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This could be bacause your ant+ USB receiver is not close enough to your bike’s ant+ transmitters (power/cadence) I have found that by using a USB extension cord (3 - 6 feet0 this has successfully gotten rid of power/HR/cadence dropouts - I purchased one on Amazon.

Sometimes it’s not actually to do with the ANT dongle “being close” to the sensors, but infact that it being connected directly to the USB port and the actual computer causing interference.

A simple USB extension creates distance from the port, it doesn’t necessarily need to be inches within the ANT sensors, just away from the computer.

thank you all for your feed back… Being its a laptop, It is entirely possible that the laptop is interfering with the ANT dongle… I’ll pick up an extension cable and update this thread Saturday…

thank you again.
may merckx be with you!

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I had the same issue but I SOLVED it… by moving the computer closer to the sensors on the bike. The computer with the dongle plugged in was maybe 5 feet away from the bike, i guess that’s too far. As soon as I moved it closer, maybe a foot or so near the bike, it no longer looses signal. Woohoo! 

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Today I attempted to do the FTP Test (shorter) and I had the same issue and my Mac is always next to me, I haven’t done anything different from what I did on my previous rides and it worked perfect. If anybody at Zwift reads this post, it will be nice to get this fixed.

I’ve attached some pictures with different power readings that don’t make sense logically with the cadence and heart rate I had at the moment.

Rony V.


Same as Rony Vega–Today I was doing the longer FTP test. All went well until 10 minutes in the the FTP segment, when all of a sudden the power dropped to zero then came back up and then dropped to zero and my rider dismounted.

No one in the household was streaming, which has caused this issue in the past. 

Will try again next week and will make sure all other WiFi devices in the household are not using bandwidth.

Does Zwift respond to these conversations?  I’m experiencing the same with my Macbook and would love to know the fix.  I’m connecting a ANT+ dongle through a USB-C dongle, so maybe this is causing the problem - but I would assume that the Zwift team is trying to understand?!


Mine was a nightmare for ages. Worked really well for 1000 miles then drop outs all the time. I bought a £3 USB extender cable and that has fixed it. Give that a go its worth a try.
Ride on

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I am a level24 zwifter and originally used a computrainer until this year when I updated to a new kickr2. Zwift had been working well until a few months ago when this dropout problem emerged. I mostly do workouts and have come to accept that I will “fail” every segment despite the fact that my heart and legs will tell you otherwise! I use a Toshiba laptop with an ant dongle. My power drops to zero constantly which means group rides are out of the question. Very disappointing.

This week I decided to run zwift via my iPhone and connect the kickr with Bluetooth. It works perfectly. Not exactly the great visual experience though. Tried it on my mac, didn’t work due to the mac not being able to see a Bluetooth signal from the kickr. More disappointment.

So it’s back to the phone for now but I hope someone fixes this problem as it is really taking the enjoyment out of zwifting. 

I’ve found the answer which may or may not work for you. It’s not related to interference in anyway but the way Ant+ is negotiated between devices.

I had my power source and control set to ‘KICKR’ this causes regular dropout probably for 1-2 seconds every 10 mins or so.

I then set the control to ‘Wahoo F-EC’ and kept power as ‘KICKR’ and the problem disappeared! Another bonus is that now all the hills are much more difficult than they were when the controller is set to KickR. I don’t know why this is but it 100% worked for me.


I’ve been struggling with these exact issues for months now. I’ve worked with the techs from Zwift and tried everything except a different lap top. Does anyone have any data that supports some configuration on a Mac Book Pro that my cause the Ant+ to drop out? When mine crashes, unless you unplug the USB and run bluetooth for awhile, you can’t re-connect to the Ant+. Once you re-connect after 10 mins, the Ant+ pairs up immediately but then crashes within 30 - 60 mins. Very frustrating… Swift is saying that maybe its my providers server location but I’m not exactly buying that.



Chris Jackson

Level 25 Zwifter using PC and Computrainer.  Everything works excellent with this combo.  When I try to use my Powertap wheel for the Power instead of the Computrainer - I drop out regularly. Racing and group rides are not possible.  

I will try looking into the suggestions here:




My Issue that I fixed as already outlined in my earlier post was confirmed by Wahoo support themselves. Their devices don’t like to share Ant+ information. I’m not sure if that’s just the standard itself or their device. They confirmed if I bought a wahoo bike head unit then I could record my indoor rides on that while also Zwifting. My Garmin edge 800 would always drop out every few minutes. Basically this is the same issue as when Zwift power and controller are set to the same device - even my KICKR! Plagued for a whole year with drop outs until one day I set the controller in Zwift to Wahoo FEC and then instantly everything was 100% perfect - I could even record the power info at the same time to my Garmin headunit so I can have real-time TSS, IF and other important power related data that Zwift doesn’t give me.

If the computrainer can broadcast FEC too, make sure that the controller is using that signal and not the usual power output.

It seems the manufacturers are quick to blame environmental setup. This is not always the case and even with help from their support, I only managed to fix my issues by sheer chance of trying different things that they didn’t suggest!

Thank you, Craig Howard Kiss B!  I was having issues with short power drops to zero every few minutes, and I moved or shut off every single device that I thought had any interference with the Ant+ signal. After trying your solution, it worked perfectly!