Speed sensors issue

Have a speed , cadence , and HR sensor paired. When on the sensor pair screen all sensor values match my garmin readout. When I go to an event, the speed keeps increasing. I can go back to the sensor screen and the value is the lower , accurate reading. I’m paired with USB ANT+ to win 10. Tried restarting Pc and software several times. Also tried repairing sensors. Any suggestions??

In game your Garmin speed does not match your Zwift speed. Speed in Zwift is calculated by power, weight, gradient etc. They will seldom ever match.


Hi Nigel. It is waaaay off. Bike says 15 Zwift says 35.

Ignore Garmin’s speed display inside. It’s completely irrelevant. You’re real life bike is not on a real life road. You’re not in motion. The speed that Garmin shows on a trainer has only the slightest relationship to what your pedaling effort would deliver on a real road. The Garmin speed is not accurate inside.

Zwift has you going at (about) the virtual speed you would be traveling on a road downhill and uphill with air resistance, drafting, a specific set of wheels and a specific bike and specific clothing, etc. Your Garmin knows nothing about any of those.

Appreciate the responses but I am still not convinced.

Again, I only have. Cadence, HR and speed.

Speed correlates identical while in the pairing screen through all speeds.

However, When riding, it is near double, and the watts are rediclous. I understand with out power it is an estimate, but it’s based off cadence and HR so would be close. Only ridden stationary bikes with watt output, but I know that my 135hr can not produce 600 watts.


Tim: I expect you’re right. You don’t produce 600 watts at an easy effort.

As Nigel wrote, your Garmin speed does not match your Zwift speed.

But that does not mean that your Zwift speed is correct in Zwift. Perhaps you’re actually producing 150 or 250 watts when you’re riding at an easy/moderate effort.

The point is not that your Garmin and Zwift don’t show the same speed, it’s that the Zwift watts are unreasonably high for your level of effort.

Tell us what trainer you’re using. If it’s a wheel-on trainer, tell us what you do each time to set it up – tire pressure, etc. If it’s not one of the high-end, few trainer models that don’t require calibration, are you calibrating the trainer, and how often and when?

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Hi Tim,

it happens all the time the same to me… I have no powermeter, HR and cadence it’s right, but speed is not.

In real life, I’ve never been at 3 k/ph in a hill with 6% gradient…

I know Is just a trainer, but we don’t like to get humiliate!:joy::joy::joy:

Actually for me is totally opposite, sipped don’t match, and watts neither… .quite low

Hi guys, I have the exact issue as Tim. Cadence and HR are spot on, but the sensor speed seems to be ignored completely. Depending on the terrain and gradients, in the same gear and the same cadence (ergo same speed), I see speed ranges from 15-70kmh, driven by the terrain conditions. My wheel-on trainer is supported by Zwift, but the results it’s showing me (speed, power and distance ridden) are completely off. Any ideas?

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Read this: How Does Zwift Determine My Speed?