speed is way out when riding

(Randall Lupien (VV)) #21

Guys, something to keep in mind (and I’m by no means an expert). I note that when power goes down so does speed and vise-versa. I’m riding “dumb” rollers so I have to pay close attention to % of grade in the app. When the grade goes up I have to down shift to provide the appropriate resistance. I find that if I spin up a hill, my power goes down and so does my speed (regardless of cadence). On the other hand, if I “mash” up a hill, this keeps my power up as well as my speed. In any case, I use my actual road climbing experience to provide resistance in the app on climbs. That seems to do the trick.


(Steven) #22

The way the application deals with speed and power isn’t clear, otherwise I wouldn’t be in a position where I increase rpm when entering a hill and the application starts ratcheting my speed regardless.

I don’t want to have to pay to use a system where you have to ‘trick’ the system into doing what you want to ‘stay under X watts/kg’ to be able to get what appears to be a more consistent and more realistic ride.

It gets really frustrating for a new user to run into these situations where the ride isn’t really a ride and the rules or techniques are unknown…and untold, at least by Zwift.

Also, it doesn’t help that stupid menu items pop up and require some form of input and the laptop is across the room. Laptops and sweat don’t really go together and I purposefully have a long usb extension on this so I don’t have to be near the laptop.

Frustrated first time user.

(Mike Watson) #23

Frustrated first time user here too.  WHY CAN’T ZWIFT JUST USE THE INPUT FROM THE ANT+SPEED SENSOR?!?! All this power calculation to a speed output is completely pointless and is just pissing off the community.  Zwift, please listen to us or you’re going to lose a lot of potential subscribers!

(Russell Gowers [CRANKS] KISS (C)) #24

I’ve completely changed my mind since first posting on here.

If everyone had turbo trainers which could simulate 20% gradients then it would be fine to take the speed reading from the speed sensor. You could bump the resistance up on a gradient for fatties like me, reduce it for whippets, and parity would be restored - thin people would be faster up the climbs.

But we don’t all have turbo trainers like that. Some people have trainers where you can’t even adjust the resistance at all. So taking the Zwift speed from the ANT+ sensor would simply result in the people with the cheapest trainers being the fastest, because they could batter along untroubled by gradient changes.

The best thing to do is turn off your Garmin, ignore speed entirely and start working with power (or zPower). This will give you the most satisfaction.

(George Muenz) #25

I have been using TrainerRoad since it came out and there is never an issue with speed being accurate, but I guess it’s different in the Zwift Virtual world, because TR does take Speed/Cadence from the sensors. 

I used Zwift when it was in Beta but switched back to TR because I found myself racing on every session, but now Zwift has workouts and group rides, so coming back. The speed aspect is an issue that I’m sure irritates a lot of people, so hoping some sort of clarity will come about on that. 

(Greg Sloane) #26

First time Zwift user here and massively dissapointed that this problem exists after all this time.


My reported speed is very innacurate.

210 lbs / 6’1 on a regular road bike on Tacx Vortex.

On a flat or bit of incline and no matter how much power Im putting in I am constantly being overtaken - it is showing as 5mph or less when it should be around 15mph. Now i know from researching this that innacurate speed is to he expected and it is all about watts - but it will make group rides and  any timed stages near impossible as well.

Just spent a fortune on the trainer because I thought Zwift would be ideal for the winter training… gutted. 

(Paul) #27


That is far too little info to even begin to assist you in resolving you issue.

(Steve) #28

Greg, what power are you showing? For instance, if Zwift is showing that you’re generating 200 watts, your speed on a long flat section might be around 19 mph.

If Zwift is reading 200 watts and you’re getting 5 mph on a long flat section, that sounds like one issue. If you think you’re pedaling hard but Zwift is showing 30 watts, that’s a different issue.

(Greg Sloane) #29

@Paul - I’m new to this so wasn’t sure what info is needed - apologies.

I think it is actually sorted now.

I think it was one of two things:

I left the calibration app connected via bluetooth from my phone. Apparently that can cause problems.
Also reduced the "Trainer difficulty " to about 40%. 

Now on a flat road at 200w it seems to get between 15-18mph - so thats about right… right?

(Steve) #30


Using the http://www.kreuzotter.de/english/espeed.htm calculator, I see 17.5 mph for a solo rider 73 inches tall, 210 pounds, riding with hands on the tops of the bars on a flat road at sea level. So 15 to 18 mph in Zwift sounds reasonable. 

(Greg Sloane) #31

Nice one - thanks very much Steve :slight_smile: