# Pairing both Speed Sensor (Garmin) and Power Source (Vortex Smart)

**URL:** <https://forums.zwift.com/t/pairing-both-speed-sensor-garmin-and-power-source-vortex-smart/828>\
**Category:** Archived: General Discussion\
**Created:** [January 30, 2017, 9:34pm UTC](https://forums.zwift.com/t/pairing-both-speed-sensor-garmin-and-power-source-vortex-smart/828 "2017-01-30T21:34:41Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![clapit\_lucca](https://avatars.discourse-cdn.com/v4/letter/c/b77776/32.png) [@clapit\_lucca](https://forums.zwift.com/u/clapit_lucca)\
**Post date:** [January 30, 2017, 9:34pm UTC](https://forums.zwift.com/t/pairing-both-speed-sensor-garmin-and-power-source-vortex-smart/828/1 "2017-01-30T21:34:41Z")

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I play using a MacBook Pro (Sierra) with Ant+ and Tacx Vortex Smart  
I just paired Garmin Cadence and HR sensors (they works perfectly) but not Speed Sensor.  
May I pair both a Speed Sensor (Garmin) and a Power Source (Vortex Smart)?  
Vortex’s speed values are not accurate in Zwift…

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**Author:** ![Paul\_Allen](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/paul_allen/32/414916_2.png) [@Paul\_Allen](https://forums.zwift.com/u/Paul_Allen)\
**Post date:** [January 30, 2017, 9:58pm UTC](https://forums.zwift.com/t/pairing-both-speed-sensor-garmin-and-power-source-vortex-smart/828/2 "2017-01-30T21:58:14Z")

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I would suggest not using the speed sensor, you will then be using zPower, you should only pair the Vortex since it has a built in power meter.

What do you mean the speed values are not accurate? Speed within Zwift is based on watts, your weight and the virtual terrain.

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**Author:** ![clapit\_lucca](https://avatars.discourse-cdn.com/v4/letter/c/b77776/32.png) [@clapit\_lucca](https://forums.zwift.com/u/clapit_lucca)\
**Post date:** [January 30, 2017, 10:41pm UTC](https://forums.zwift.com/t/pairing-both-speed-sensor-garmin-and-power-source-vortex-smart/828/3 "2017-01-30T22:41:11Z")

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Thanx Paul!  
I play dressing my Polar RC3 GPS too, with related W.I.N.D. sensors of Cadence, Speed and HR.  
I have no Power sensor.  
I have installed and paired Garmin Cadence and HR sensors (Ant+) and values are exactly the same of Polar.  
Speed read by Vortex Smart on Zwift is very faster then Polar and covered Distance &nbsp;results obviously much longer.  
I’m a newbie, maybe I should not care about Speed but only Power!  
Sorry for my bad English…

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**Author:** ![Paul\_Allen](https://sea2.discourse-cdn.com/gozwift/user_avatar/forums.zwift.com/paul_allen/32/414916_2.png) [@Paul\_Allen](https://forums.zwift.com/u/Paul_Allen)\
**Post date:** [January 31, 2017, 1:01am UTC](https://forums.zwift.com/t/pairing-both-speed-sensor-garmin-and-power-source-vortex-smart/828/4 "2017-01-31T01:01:27Z")

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Your speed in Zwift is determined by your power/watts. The Vortex has a built in power meter so Zwift will calculate your in game speed using the power broadcast from the trainer, your weight, and the virtual elevation.&nbsp;

I think you are miss understanding how Zwift works and think that the speed of your rear wheel is how fast you are going to move in Zwift and that is not the case. Zwift can calculate you power based on your read wheels speed and translate that into in game speed, but you have a smart trainer so that is a better option.&nbsp;

Power and watts per kilo gram are the name of the game in Zwift.

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**Author:** ![clapit\_lucca](https://avatars.discourse-cdn.com/v4/letter/c/b77776/32.png) [@clapit\_lucca](https://forums.zwift.com/u/clapit_lucca)\
**Post date:** [January 31, 2017, 7:17am UTC](https://forums.zwift.com/t/pairing-both-speed-sensor-garmin-and-power-source-vortex-smart/828/5 "2017-01-31T07:17:22Z")

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You are a real guru, Paul!

Thanks so much from Italy!