Slow speed on zwift!

Bugs and Support
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Hi all! I´m new to zwift and recently got my Kicker Snap. I´m having issues with my speed being really low! I usually go at a pretty good pace but not incredibly fast (outside). I Recently made a 1hr workout (Watopia) making only 19.4 km, while in real life with a similar course profile make almost double.

Checked the tire pressure to be over 100 PSI and tried re-doing the Wahoo calibration several times and increasing and decreasing my FTP manually but the changes are very small. My average watts for the workout was 68 which consider incredibly small compared to the amount of effort I put on.

I got a specialized allez road bike with the kicker snap. Don’t have heart rate, speed or cadence monitors.

What am I doing wrong? Do you need a cadence or speed meter for it to really feel much faster?

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Hi Sebastian!
If you can calibrate your trainer and your tire pressure is good then you should be all set. I don’t have a wheel on trainer myself but I know that pressure against the wheel matters so read up on how tight to set your pressure against your wheel.
You didn’t mention if your speed goes up and down as you pedal or if it stays the same. Zwift will calculate speed. What numbers do you see when you ride? You should see power, cadence and speed.
One more thing under settings, the little gear icon. You can set trainer difficulty which is basically how much you will feel hills. 100% is max and you’ll need to shift a lot while 0% is like a dumb trainer and everything feels the same. Try riding with it at 0%. I set mine at about 35%.
That’s all I got and hopefully this gives you a few things to try. Let us know if your speed and power numbers are changing as you pedal or do they stay fixed.

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I second the recommendation to check how much the roller is pressing into the tire. I use a Snap and you want to have the roller pushing JUST far enough into the tire so there is no slip when you try to up the pace while riding, or if you start climbing a steep incline. If you push the roller in too far you create huge resistance which will make it hard to generate any speed. You will also wear the tire down VERY quickly. It will take some trial and error to get it right.

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Also read this: How Does Zwift Determine My Speed? - #4

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I would say this is definitely a calibration issue. If you can average over 30km/h outside, then your average power should be much higher. I imagine at least double.

Changing ftp or trainer difficulty on Zwift will have no effect. Your speed is only a calculation from power, so nothing you can do there. Cadence measurement is useful, but will not affect anything else.

The Kickr should be accurate once everything is set up, but I saw this on Bikeradar:

## Wahoo Kickr Snap power measurement

On the first test unit we had the power numbers kept dropping out every few seconds, regardless of software used. We’d see a reading for a few seconds, then 0, then a reading, then 0, etc. Wahoo exchanged the unit and the replacement did not have this issue.

In initial testing, we found power measurement to be off by 40–80 watts, compared to reliable power meters, after completing Wahoo’s spindown calibration. In our initial review published 11 January 11 2016, we called the Snap’s power measurement lousy. Turns out, the situation is a bit more complicated.

For the Snap to correctly measure power, two factors must be considered.

One is the rolling resistance, which includes the tire and the flywheel’s inertia. This is what the standard spindown measures and accounts for.

The second is the electromagnetic brake. Wahoo CEO Chip Hawkins said the unit’s algorithm for power measurement is based on the pilot batch of Snap trainers — and that subsequent batches of Snaps had a different factory configuration, something Wahoo only discovered after the fact. Thus, the advanced spindown must be completed by users to measure and calibrate for the unit’s brake in order to get accurate readings. This only needs to be done once, but it does require the latest version of the Wahoo app.

Also Shane Miller AKA GP Lama has a good video (with more links too) Wahoo Kickr SNAP Smart Trainer: Unboxing. Building. First Ride. - YouTube

Hope you can get it sorted, Zwift is not so fun if your power is not accurate!

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