Can some one help me please

I am using Cyclops jet fluid pro with Garmin edge 800, GCS10, HR monitor and all linked to Zwift with ANT+ on extension lead. My issue is that when riding Zwift says I am doing 4mph and my Garmin says 17mph and my legs agree with Garmin, what s the issue am I doing something wrong? 

When you are going 4mph are you going up a hill/mountain within Zwift?

I have this trainer, though my setup is via bluetooth to my Mac. Are you sure you set it up as Jet Fluid as the trainer unit is the same as Jet Fluid Pro, the pro only has better looking wheelbase. Initially I mistakenly put my trainer as Fluid 2 or maybe another one (can’t remember) and I could not even reach 15 mph. I had to exit and do it again. 

Also you should ensure your tire pressure is 100 PSI and the trainer is setup properly with two clicks. Higher pressure would make it more difficult as more power would be needed to turn the turbo. Lower pressure would make you go faster as it will inflate your power figures in Zwift. Tyres lose 1 PSI a day so it is good to check every few days. 

Also weight would make a difference also. If you put your weight higher than you normally are you will be slower on climbs. It will have little effect on the flats though. Just ensure your weight/height numbers are accurate.   

With virtual powerr/zpower I feel like I am a bit slower. Maybe the zwift code penalizes us zpower more now as previously there were too many fliers. But this is only my speculation. I am coming back after a few months so naturally would be slower than my former self. 

Thanks for the replies, 

Paul, yes the difference in speed is more noticeable when Zwift is going uphill. 

Tauseef, I will check my tyre pressure and my weight, trainer is ok got two clicks. Might try with bluetooth see if it is any better.

 

Thanks