ANT+ Dropouts on Snap?

Despite reading all the KB and Community posts on drop outs on SNAP trainers, Im still having the following problem:



  1. New SNAP device in Feb17. Latest firmware and using the iphone Wahoo app, power is pretty consistent with no significant variance +/1 5% on average.

  2. For ZWIFT I use a laptop. connected to the internet via WiFi. Laptop is connected to trainer plus HR and Cadence devices via ANT+ (10ft USB cable from laptop to just by trainer legs).

So, I think Ive ruled out the SNAP as using the wahoo app on bluetooth its ok.

Now Im thinking interference but I dont get complete drop outs just significane variance in power +/1 30% sometimes.

Only other devices between Laptop and Wifi Router is a fan (5ft away from ANT+ dongle. TV is half way between laptop and router (15ft).

Is there a way of working out whether its problem between the ANT+ dongle and the laptop, or laptop to router?

Any ideas appreciated.



My first instinct is to check that 10ft USB cable, not all of them are very good. I have had problems with a cheap 3ft one.


Thanks, yes good point. Ive also realised another good test would be to connect via BLE only with the trainer leaving ANT+ disconnected. It has to bridge through my iphone but worth a go.

Also Ive been using my laptop on battery and not plugging it in, so wonder if its been reducing power to USB ports. 

Do older USB ports cause problems? (Laptop is a work one circa 2012) but ANT+ dongle is USB2.0 and detects everything ok.

Will report back.

Ok, looks the following has worked for me… so here goes it may help some people.

If you receive significant power spikes/drops in Zwift when using a Wahoo SNAP and ANT+ connectivity to Zwift complete the following:


Step 1.

Follow the correct spin down and advanced spin down procedure recommended by Wahoo including the correct resistance of the roller to the rear wheel. All this info can be found on their site or from their support team.

Step 2.

Test using the Wahoo Fitness App in IOS or Android. This uses Bluetooth so can help troubleshoot whether its an ANT+ issue or possibly the trainer.

Step 3.

If the power remains relatively steady in the Wahoo Fitness App (there is always some small variance unless you are super steady on the pedals), then goto Step 4.

If there is still significant variance contact Wahoo Support, or you could try what this chap has done ( This has solved quite a number of peoples issues.


Step 4

Use a laptop or PC with just bluetooth using your IOS or Android device as the BLE bridge with Zwift mobile link app. 

As you had relatively steady power figures through the Wahoo App you should see the same result now in Zwift. If not it could be an internet connection issue. May be worth calling Zwift at this point if there is still a problem in Zwift.

Step 5. 

Assuming everything worked ok with bluetooth and Zwift, now look at the following when using ANT+ and Zwift

  • Remove all other USB devices where possible (eg wireless mouse, BLE headsets etc).
  • Zwift only works with USB2.0 so if you have an old garmin dongle (it may not work).
  • Ensure if you are using a laptop it is powered and not using battery
  • Check USB ports are not configured to go into power saving mode
  • If you PC/laptop is more than a few feet away from trainer then get a decent USB extension cable. Then run the cable from the PC/Laptop all the way to the trainer.

The above has worked for me. It ended up being a combination of laptop power and other USB devices plus the need to run a 10ft USB cable.

Hope it helps.

Suffered from severe drop outs using ANT+. Tried it all, including active USB cable. That helped a little bit, (from 60 drop outs per hour to 30). Racing was a nightmare, group rides ok.

Changed to bluetooth - problem solved, not a single drop out. Hope this can be a helpful experience to others?

I have experienced many dropouts and was able to get them under control with the following fixes (mostly from

  • cleaning the sensor and mounting it closer to the bright target on the flywheel
  • replacing the bright target with a silver foil target
  • using an active USB cable
  • selecting FE-C as the connection type.  Standard ANT+ seems to have occasional dropouts when the applied effort changes abruptly.

I also tried bluetooth connection which I felt was partially successful. However, I felt that the power reading was not accurate – a subjective measure to be sure. Some firmware updates were helpful, others masked the problem with averaging.  I now use the recommended release version.  The biggest improvement for my setup was to fix the sensor – dropouts went away almost completely.

Are you talking about a wahoo SNAP?  What’s the “bright target” you are discussing?  If this is a fix to boost ANT+ signal it would be good to do!!





Hi David,

The bright target is the reflective tape inside the KICKR Snap housing, on the inside of the flywheel.  The original tape is about 3cmx3cm and is white.  I covered it with a similarly sized piece of foil tape.  I also moved the sensor closer to the flywheel by creating a wedge under the sensor using electrical tape.  The youtube video shows most of this.