Speed sensor pairs, in game speed low

Hello everyone. I am trying to setup and use Zwift on an older road bike and Cycleops fan trainer. I know the general consensus is to purchase a smart trainer but I am looking for a solution before this is possible.

I have the Garmin speed, cadence, and heart rate sensors which connect to my Fenix 5 simultaneous to my PC desktop where I have Bluetooth and ANT+ connection (both have had the same results which is where that is relevant).

When I pair the equipment everything goes smoothly. The speed sensor even shows a reading in the paired screen which is consistent (close enough without the Zwift map variables) with my Garmin watch, we’ll say between 15-20mph. I then enter the game and either just ride the course or try a workout. I often make it 5-10 minutes before the speed completely drops from a reasonable cycling speed down to 3-5mph, pedaling faster does absolutely nothing and eventually I come to a near standstill. This occurs while I am pedaling at the same pace so I know it is not a change in what I am doing.

I have tried this on Bluetooth, ANT+, and even moved the sensors closer together thinking it is a connection issue. While this problem occurs and while I am still riding I will go back into the pair screen, where it continues to display a more accurate reading of my speed and is consistent with my Garmin watch. I know I have a very dumb trainer setup but I cannot figure out why it would display appropriately in the pair screen AND work from the start, then display a low setting as I continue my ride.

Any help would be appreciated!

Hi @Cameron_Apt

Welcome to the forum.

Your Garmin and Zwift won’t show the same speed in the game.

When the road go up your speed will go down if you hold the same power.

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Hello @Gerrie_Delport_ODZ.

I do understand that but my concern is that the speed within the Zwift pairing screen is not consistent with the speed on the Zwift in-game riding screen. It also works perfectly well to start and then shows a discrepancy with the in-put effort and out-put speed as compared to the same ride start to finish.

I am not concerned with it not showing numbers consistent with Garmin, that is just my reference, I am concerned that it seems as if the display is not accurate as with the true reading of the Garmin speed sensor and as shown within Zwifts own pairing menu.

I know @Gerrie_Delport_ODZ is going to post this sooner or later: https://forums.zwift.com/t/how-does-zwift-determine-my-speed


LOL :joy::joy: I was just getting the link.

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That makes sense. I will give it a shot and see it through.

Thank you

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Your displayed speed decreases, do your power numbers also drop?

No, power numbers seem to remain “normal”. Although I will admit I have not paid as much attention to them in the process as my speed slows to 0.