Synthetic cadence?

I witnessed something odd today I’ll call synthetic cadence. After the episode I found my cadence sensor had disconnected from the PC/ANT-ness, and I was able to “re-search” and find it and everything was ok. During the issue, though, and before I realized it was disconnected, I started noticing that the cadence seemed oddly high. Before I checked the sensor status I did some research and found that while I was riding at 90rpm (using a stopwatch) Zwift was reporting between 95 and 115 or so. The latter/higher values were while riding fast downhill. It leads me to think there is some cadence guessing/synthesis going on when a sensor isn’t present or working? If so, it’s a little high!

Zwift does in fact fabricate a cadence value based on a combination of speed and power, and it’s there only to keep the rider animating reasonably. Given only a power number it’s impossible for us to guess a reasonable cadence value for all situations, so the fact it was guessing 100 when you were at 90 is pretty impressive in itself.

The next version of Zwift will make it more obvious when Zwift is using faked cadence vs a real signal so there will be less confusion about what the number is.