RPM Sensor Workout Requirement?

So, when I’m doing a workout, the ftp builder for instance, there’s a 5 minute section that requires power and an rpm…What do you do if you don’t have an rpm sensor? Just don’t do the workouts? I was spinning as fast as I could, which I know would be well over 105, but it kept asking me to spin faster…I’ve never had these workouts work as it’s always something.

I can’t be the only person who thinks these workouts are garbage. Is there any documentation anywhere explaining how to properly set up for the workouts?


Buy one? It’s $40 well-spent.

The workouts aren’t garbage. Training to make the same power at different cadences (or to make high power at low cadence with rests @ high cadence or vice versa) will make you a better cyclist.

You can’t really fault the workout for telling you to spin faster when the target is 90 RPM and your current value is nil.

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How else is Zwift supposed to determine your performance? If you want to do anything beyond the most basic rides, you’ll need a few more components.


Workouts in the Build Me Up plan will not fail you for not having a cadence sensor. You can complete them just fine without one. However as the others have already said, the cadence training with accurate power training will make you a better cyclist.

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Just buy a pedal based power meter. Power meters aren’t expensive anymore.

FYI - I just purchased a second cadence sensor a minute ago because I was getting tired of moving one sensor between two bikes (road and cx) all the time. It’s not exaclty ‘hard’ to move it (just a simple zip tie) - but it gets old.

Anyway, I’ve been meaning to buy another for a long time - and this thread prompted me to do it.

FWIW - if you use ANT+, jensonusa.com has a 20% off code (save20) for full priced items. Gets you the Garmin Cadence 2 sensor for $32.

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‘aren’t expensive’ is really subjective. $600 for pedals is still quite a lot vs. $32 for a sensor, especially if he already has an accurate power meter built in to the trainer.

I’m not saying I disagree with you, per se. Just that for most folks, $600 isn’t exactly pocket change.


Yeah, I’m pretty sure it was showing my cadence at 62, for some reason. I’m a developer, so I assumed someone at Zwift knows how to code, but doesn’t really know much of anything else thought they could back calculate my pedaling RPMs from my rear wheel RPMs without knowing teeth counts on the crank. I meant to buy a cadence sensor a while ago and just forgot to hit buy on the Amazon cart last time I dealt with this. This will make it more enjoyable as I feel like climbing the mountains and such can only improve me so much. I need to be pushed.


I was thinking more along the lines of $1200 for a good PM. I’m not rich but I have three powermeters

That’s odd, unless your trainer has a built-in cadence function. What trainer do you use?

Mine (Elite Direto) can send a cadence signal to Zwift, but it’s pretty erratic until the resistance starts to ramp up. Below ~ 200W, it tends to jump around a lot (e.g. I can spin smoothly at 100 RPM and my cadence in Zwift will drop down to 60something, then spike back up, then down again, etc). At higher wattage, it’s more stable and consistent w/ an external sensor - but it’s annoying enough that I generally pair my Garmin sensor instead.

Wahoo Kickr. I didn’t investigate it any further, but it definitely shows my cadence as 60 when I don’t have a cadence sensor paired as I found out when I first started using the wahoo cadence sensor. I just bought the wahoo cadence sensor and it works fine now.

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