Workout watts vs non-workout watts

(Mark Weiss (AZ)) #1

FTP test results and workout wattages seem to match. Workouts using my FTP test results push me to appropriate levels as indicated in the workout profile. However, I find that when I am not riding a workout I have wattage readings that are well above what I would expect. While this is not too bad during a group ride, I do normally receive a suggestion to adjust my FTP upward at the end of every non-workout ride. So I am wondering, why the difference?

(Gerrie Delport) #2

If you ride harder in the non workout vs FTP test Zwift will suggest that you adjust your FTP.


This may be a dumb Question but did you check if your FTP is correct on the User Profile page?

(Mark Weiss (AZ)) #3

Good question, yes. The first time I recived the suggestion to raise my FTP I did so. Then found that the workouts had become impossible for me. I went to my profile and reset FTP to where it had been.

I really don’t think that I am riding harder during non-workouts. The FTP tests feel as if they are maximum effort. The last time that I ran one I re-rode it a few days later, just to confirm the result.

Still, if I set FTP to the level suggested after a non-workout ride, I cannot complete many of the workout schedules.

(Gerrie Delport) #4

What trainer do you have. (dumb or Smart)

Can you describe “Then found that the workouts had become impossible for me”

Is it to hard to pedal?

(Mark Weiss (AZ)) #5

Kickr Snap, FTP results were 152, non workout riding usually recommends about 180.

Much of the time I have been riding in one of the FTP bullder programs. At 152 I can fully perform any workout I try. High effort workouts, i.e. Climbing, Strength, Intervals, usually take me near my maximum output. If I raise FTP to 160, I do go to max output at times and sometimes cannot finish high effort blocks near the end of the workout. At 180 I can complete Foundation workouts with high effort levels, but cannot complete high level effort blocks in either Strength or Tempo workouts.

(Jason K) #6

There’s a couple leads I can see in your account history:

  1. It looks like you previously had a TravelTrac paired under zPower. It’s unlikely, but there could be a bug where the previous pairing is being remembered and affecting your current pairing with the SNAP. I’d recommend deleting your prefs.xml file to reset your preferences and eliminate this possibility.

2. If you haven’t done a spindown calibration recently, give that a shot. Could just be time to do a simple hardware check. If you’re still seeing the issue after that, contact Wahoo support - I believe they can check to make sure the trainer is operating within acceptable ranges based on your spindown results.

(Mark Weiss (AZ)) #7

The TravelTrac has not been used in about 10 months, but I’ll take care of the file now. I run a standard spindown about every ten rides and I’ll conduct one tomorrow, just to be sure. Then it will be several more days before I have results.

Thanks for the pointers.

(Mark Weiss (AZ)) #8

I had forgotten to note earlier, while my FTP tests were indeed the best effort that I could muster at the time, the results from non-workout rides are from only just above moderate effort. Work sometimes takes me away for a week or so and the non-workout rides are what I do to ease back into the Zwift routine.

(Mark Weiss (AZ)) #9

A result and a curiosity. This morning I trashed the old “prefs” file and then did a twenty minute warmup of the Kickr and ran a standard spindown. A one eighth turn adjustment of the tensioner and then two more spindowns, just to be certain. With all readings within expected parameters I rode the shorter FTP test. I chose the shorter test because I was already adequately warmed up. The test was grueling as expected and returned a new FTP number of 165. That is about what I had expected since it had been several months since the last test. I did notice though that just before the “average power” display vanished from the screen the reading had been at 170. I thought that FTP was average power over 20 minutes?

Next, to do a free ride.

By the way, I’m not overly concerned about these numbers. To me, it is little more than a curiosity. Like why is my maximum heartrate higher for outdoor riding than it is for indoor?


(Mark Weiss (AZ)) #10

A test, a result, an observation, and a hypothesis.

I have now run a non-workout ride. In an attempt to replicate the conditions of the FTP test as closely as possible I checked my tire inflation and rode a thorough warmup of the Kickr Snap, then ran a few standard spindowns. No adjustment was needed. Next, in order to keep the machine resistance as nearly constant as possible I chose the London 8 route to minimize climbs and avoided Box Hill (I u-turned when I approached the hill). I rode a ten minute warm-up pattern and then rode fairly hard for one half hour. Because I was not running a specific routine and Zwift would not hold resistance constant, I kept my effort fairly steady by closely monitoring my heart rate. I did not want to inadvertently find myself trying to over run my FTP effort so I noted that during the FTP test my heart rate ran in the upper 150s to lower 160s. During this non-workout ride I did my best to maintain my heart rate around 150. There was one accidental bump up to the low 160s when I rode the stairs up out of the Tube, but that was only a brief excursion. Beyond that, 150 or so was the rule.

In the end, Zwift recommended that I bump FTP to 174. Not the 180 recommendation that I recieved when I started this thread, but still notably more than the FTP test result. This was a deliberately controlled ride and that could explain the lower reading. As I thought about this I began to wonder if the varying efforts experienced in the non-test ride may have contributed to the higher overall result? During an actual FTP test I ride continuosly at the maximum output that I believe that I can maintain through the entire test. I have believed that I’ve been going about this correctly because I find that my output begins to fade during the last five minutes or so of the test despite that fact that my percieved effort (and heart rate) is increasing. During the non-test test changes in the virtual terrain meant that I was regularly adjusting my efforts. Periodic increases and decreases occurred because of the moderate inclines and descents which were presented. This makes me wonder if pedaling with varying effot levels during an actual FTP test would achieve a higher result. Possibly periods of slightly ligher loads mixed with periods of slightly higher effort would yeild a higher average power reading?

I’ll still check with Wahoo to verify the operation of my trainer, but I think that more research is indicated. I’ll not be riding another FTP test in the next few days though!

(Gerrie Delport) #11

This is a very detailed test that you did. did you save these rides on Strava. I would like to take a look at them and compare them. I dont know if I will find anything but it will be interesting.

(Mark Weiss (AZ)) #12

Yes, both rides are recorded. FTP was late last week and the non-workout ride was yesterday morning.

(Bret Giuliani - RtR) #13


I have the same issue, and have a Snap as well.  ERG mode is *much* more strenuous than free ride for the same wattage (starting somewhere around 140 watts).  It’s something I’ve just come to expect.  Been that way since I got the Snap last winter.

For giggles, I might try deleting my prefs.xml.  I did have a dumb Cyclops paired when I first signed up with Zwift back when.

I’ve always figured this was a bug, and just accepted the fact that my FTP would always be weak in ERG mode…