I just got a new smart trainer (JetBlack Victory) and was excited to try out ERG mode in Zwift for the first time – previously, I only had power pedals on an old indoor bike with felt resistance, and I had to adjust the braking force manually all the time.
Today, I picked the XERT workout “SMART – Closer 200 (Short)” – it should be tough, but doable. So I exported it to Zwift, selected it there, and got started. In the image, you can see what it was supposed to look like: challenging, but the MPA still relatively far away – so it should have been manageable.
However, at the end of the first interval I thought: Oh my God, THAT was just the first of five intervals? Why am I so weak? Was it the avocado sandwiches? Is the power measurement completely miscalibrated now – or was it miscalibrated before on my power meter pedals?
I pushed through, but it didn’t feel “tough” – it felt like I was at my absolute limit.
Then came the surprise in Xert: my feeling wasn’t wrong. It really was at the limit. It was way harder and with a personal record of 235 XSS - double the expected amount. See screenshot.
You didn’t do anything wrong, but Zwift can’t play some SMART intervals like the hard-start ones in the Closer series. Instead, the XSS per hour interval gets converted to a simple ramp. Those intervals will be easier or harder to do in Zwift. In this case a LOT harder.
If you want to avoid this issue look for curvilinear profiles on the Xert chart and don’t try to ride those workouts on Zwift.
Or run EBC on your phone for this style workout. EBC monitors the effort and adjusts the target watts accordingly. To ride around in Zwift while doing so, connect Zwift to power only if you can. For example, connect Zwift to your crank or pedals for power while EBC connects to your trainer.
Another option is to recognize the workout will be harder than intended, so instead of ERG ride it in Slope mode on Zwift, tapering the target watts as strain builds. The goal for this workout is to reach a VO2max state and hang there as best you can, not kill yourself.
Since you flatlined MPA on the last three intervals I assume you earned a BT and the chart you posted is the pre-BT version, correct?
A BT is warranted as normally you’ll never reach a Difficulty score of 200.
Your updated “absolute limit” is applied to the post-BT analysis chart. Only one interval will show MPA touching the watts you held on those intervals.
Thank you so much, know I understand why I nearly died: it was a linear decline in Zwift and not a negative exponential one like in Xert. I suppose it would be possible to approximate the negative exponential simply by multiple consecutive linear declines, maybe that would be an worthy feature for the export module to zwift.
Two follow-up questions though:
So its only the workouts with curved power demands, right? Every linear one should be exported accurately to Zwift? Or are there more types of workouts in Xert, which will be interpreted differently by Zwift? E.g. because of different FTP setup in my Zwift profile? Or anything like that. Dont want to relive this experience Still feeling it very much today.
Yes, it was a breakthrough, but only minor (+3 TP). Can you please elaborate on your comment about the high XSS in 56 minutes? Is it still plausible with this only minor breakthrough or does this high XSS indicate some problems with power measurement of any kind?
It’s actually a bit more complex than an exponentially decaying target… The target is based on your MPA and recalculated second by second on the fly. You just don’t notice it as much when doing the workouts in ERG mode, since the trainer keeps you on target the whole time. However, If you did this without ERG control and sprinted out the first 20s of each interval, the entire rest of the interval will adjust!
Not one other platform can recalculate or adjust interval targets interactively which is why we typically recommend doing the SMART workouts with our Xert EBC app.
SMART intervals that are dynamic power or duration are the main issue.
Other SMART workouts will convert fine, but you’ll need to compare the thumbnail charts between Xert and Zwift to make sure.
Workouts tagged MIXEDMODE will also operate differently on Zwift.
On EBC the interval will automatically switch to Slope mode from AUTO and you’d use gears/cadence to hit target watts. In some cases, the target is a max effort at whatever watts you can muster.
Those intervals are converted to Free Ride entries on Zwift. I.e. gears/cadence applies, but there won’t be a target shown on Zwift. You’ll need to glance at the workout chart on Xert beforehand to confirm the intended targets.
I was talking about Difficulty level which is function of XSS per hour.
Normally the shaded portion of the chart (Difficulty score) will never exceed 200.
See: Difficulty Score – Xert
Try this experiment –
View the activity details, raise the TP value below the chart a few points, then click Refresh.
How many points above current TP do you need to go before the MPA line just touches one of the intervals? Purple sections will turn to red and shaded portion of chart should drop below the ceiling (200).
Still feeling it very much today.