Speed and Cadence off on new Zwift Hub

I am new to Zwift and the forum. I have recently set up the Zwift Hub mounting a road bike with Shimano 105, 10 speed cassette. I set the “Trainer Difficulty” bar to about 2/3 of max and did a 30 minute test ride on a level ride with little elevation. Note that I also did a successful calibration spin earlier. The speed, power and cadence sensing are all sourced from and paired with the Zwift Hub. I also have a heart rate monitor paired. Pedaling in the highest gear at a brisk cadence on the real road gets my around 40 mph. On the hub around 20. Pedaling at an estimated 120 (or as fast as I could without bouncing on the saddle) ranged from between 50 and 90 on the hub. It also felt like too easy to achieve the watts displayed. Can someone point me in the right direction (article, video, tutorial) that can help me get more realistic performance and effort characteristics from the hub? Thanks,

Hi @BoltonBerry welcome to Zwift forums and Zwift in general!

At the heart of everything, Zwift is predicated on power - that is to say, how many watts you’re able to put out. On a controllable smart trainer, not only is it important to calibrate the trainer, but to calibrate YOU - i.e. how much power you sustain for X minutes. This is called your functional threshold power (FTP), and depending on the type of test, it might be a 5 minute, 20 minute, or 60 minute test.

Here is our Support Hub article on FTP tests, and how you can do one to measure yours.

If your FTP setting is too low - especially when you’re in workout (ERG) mode - the trainer will not provide enough resistance. If your FTP setting is unrealistically high - the game thinks you’re much stronger than you are, and will control the trainer’s resistance so high you might have a hard time getting the pedals to move at all.

A quick way to check this is to manually adjust your FTP number, then try a workout. During the workout, you can also nudge the FTP bias +/- 25% (different from setting your base FTP number).

You can try both of those to see if it fixes what’s bugging you, but better still is to do the FTP ramp test. It’s gonna be hard, but the point of the ramp test is to pedal to the point of exhaustion and find out where your limit lies.

1 Like

Thanks so much! I will look into that to calibrate power output. But does that affect the speed and cadence issue with the Hub? When pedaling at my highest sustainable cadence in top gear on the real road, I am achieving speeds around 40 mph. The Hub registers this high cadence at between 40 and 90 (don’t understand the low numbers or the wide variation) and the speed at around 20mph. Are the three related? I am not sure why speed and cadence are so far off from what I see on the road.

It sounds like your FTP is set too low if you’re spinning out your highest gear. When the FTP is too low, so is resistance, and your cadence numbers might also read inaccurately.

Pedaling cadence and power output are closely related IRL as well as in-game. Someone who’s a pedal-masher might generate the same watts using a “heavier” gear as someone who’s able to spin an easier gear at a higher RPM.

When Zwifting in ERG mode (“workout” mode), you’ll be prompted to increase or decrease to hit a certain power target. The game will lower the resistance you feel as you pedal faster, and increase the resistance if you pedal slower to keep you X watts of power output.

High cadence and low cadence pedaling styles both have practical applications depending on what muscle groups you want to activate (or rest).One style is not “better” than the other - there are times when you want to apply one or the other.

You can read more about how ERG mode works on our Support Hub..

Thanks . On some rides, all is well. On workout rides, not so much. I am working with Zwift Tech support on a number of possible resolutions and hope to have an answer soon. I will share your thoughts with them. Thanks again.