I have had a problem for about a month now. The wattage shown at the top of the screen is very erratic. For instance, if I am riding at 250w, the wattage will jump around constantly from about 220w to about 280w and everything in between.
This happens in all modes (free ride, erg mode etc). Just yesterday I did an 20 minute FTP test. I knew I wanted to maintain an average of 250w but because of the erraticism I couldn’t tell what wattage I was putting out.
I have the Power Display setting at 3 sec avg which always used to smooth out the wattage and worked well for me but now it does not.
Could you help, please?
My set up is Wattbike Atom running firmware version 1.02.01 with MacOS version 11.6.8 (MacOS Big Sur).
Extra info: this issue started happening at the same time as the problems with resistance not changing going up hills or in erg mode, so maybe something to do with the same release?
This is normal. This is a pretty small level of variation - remember you are not constantly pushing down on the pedals, there will be less output on your upstroke, and this will depend on your pedalling efficiency.
Some trainers use power smoothing to make the jumps less erratic.
It is not normal. At least it wasn’t until the release that also caused the lack of resistance going uphill. This has only been happening since then. I do expect some level of variation, of course, but it used to be much lower.
Perhaps my pedals stroke is reasonably efficient but if I was riding at 250w, I would expect variation between say 240w and 260w but generally pretty stable, especially with Power Display set at 3 sec avg. It is now far more erratic than it used to be.
Zwift is the only app I use. I could test it by using the Wattbike Hub but, as I say, this was never a problem before about a month ago.
And for clarity, I’m talking about when riding consistently, like in a time trial, FTP test or in an ERG controlled workout. When I’m free riding going up and down hills or in a race I do expect more variation naturally.
I promise you it is normal. The Wattbike uses power smoothing (which is why you think it’s normal). It is likely that this has stopped working for whatever reason.
I would check your power output in the Wattbike Hub app first and see if it mirrors what you are seeing on Zwift. I would expect it to be identical.
I agree with James. It sounds like power smoothing for reporting has stopped working and you’re now seeing your real power figures. There’s no way you could hold actual power of between 240 amd 260w, I’m afraid, since there are so many variations in a typical pedalling stroke. Yes, power smoothing could fool you into thinking that you were never previously producing outside that range.
Wattbike recently made some changes to their power smoothing. There’s a checkbox located at:
Settings (Gearwheel at top right) > Profile > Ride Settings
It makes your power output look really smooth. My vanity outweighed my preference for truth for about 4 days, and then I changed it back.
As always, the key is not to look at the power number, because you’ll seesaw. Work out the cadence you need to maintain desired power in the gear you’re in, and then try to maintain that cadence.
If I do that, I can actually be quite a bit smoother doing workouts in resistance mode than I am in Erg mode. Humans 1 Machines 0
Alternately, use a bike computer with a 30 second smoothing display. I often use that in TTs and just ignore the on-screen output (assuming you can connect a Wattbike to a computer via ANT). Both Garmin Edge and Wahoo Elmnt can show multiple power fields.
Thank you everyone. This gives me a lot of good information. Yes Wattbike did update the firmware about a month ago. Maybe a combination of Wattbike’s smoothing and having the 3 Sec Avg turned on in Zwift has flattered me all this time.
I will try the new Wattbike power smoothing option and see how I go. Or maybe I just have to get used to the truth
Hey Lee quick question. I know this is an old post and I’m brand new to zwift. Just got a smart bike 3 days ago new.
I got the Stages Sb 20 and I’m having the same issue as you except I have the power display set to every second. I’ve watched hundreds of hours of zwift races on YouTube and I’m positive this is not normal. Well maybe it’s “normal” but I think it’s unacceptable. Here is what I’ve noticed when keeping a smooth cadence and and not expecting more than 5% watt fluctuations.
Even on my very first ride I noticed this and ftp test. Cruising at around 200 watts, I’d drop to 85-90 for a tick or two. It has to do with erg mode. It happens when another rider blows by or when I blow by a rider and there is a short period of drafting or gradient change and zwift tells the bike to up the resistance or lower the resistance.My cadence won’t change but my watts will be all over the place.
Since I’m doing one second display it showed what’s actually going on vs the 3 second average you only see 1/3 of the true fluctuations. The delay from zwift telling the trainer/ bike to increase or decrease resistance by 10-30% and the trainer actually applying the resistance can be 2-5 seconds or so. And during that time the trainer will say it’s applying the specified resistance and based on your cadence/gear/ resistance it can be off by as much as 50% for at least a second!
Doesn’t seem like much because it’s only a second but if you are doing an ftp test in a busy road this can happen say 5-10 times during each minute segment and drastically skew your data.
I’m here strictly to race and monitor fitness. I’m not a cyclist, haven’t rode a bike in 10+years but I am a very competitive and data driven person and i absolutely love the idea of zwift racing. So my question for you is how did you resolve this issue? Or did you just accept the frustrating fluctuations?
This particular issue can be addressed by getting on a TT bike in Zwift so you don’t get any draft. It would be interesting to see if that helps or not.
I have not noticed large swings in the power numbers on my SB20 when I am not on the TT bike and someone passes me, but I rarely use ERG mode.
So on your sb 20 you don’t notice resistance going up hills? Do you see fluctuations when using power ups? How do you get away from erg mode when racing and basically anything aside from working out? I want to turn it off but you can only turn it off in a workout. I watched a video on how to disable it on the sb20, but it was an older video. The newest stages firmware doesn’t allow it in the workout screen.
ERG mode only happens in workouts, never in free rides or races, so in that context there is nothing to turn off. I do notice resistance changes on hills, depending on the adjustment of the Trainer Difficulty setting which controls how much resistance you feel on gradients. I don’t feel resistance changes from using powerups - Zwift doesn’t do that. It just makes you go faster if you are using a powerup that increases your speed such as the aero boost (if you’re going fast enough for it to matter), or the draft powerup (if there is someone in front of you to create any draft), or the feather powerup (if you are going up hill).
well I just did a race and what ever was going on before didn’t happen this time! I connect the bike and the left PM and between both I’m guessing it solved the issue so I’m 10,000% satisfied! I’m kinda thinking that for some reason one of the power meters wasnt registering or losing connection briefly. I backed the screws off and then retightened them on both just to rule that out before i rode. not sure what exactly fixed it but im happy. thanks for the info!
If it’s a connection issue between the bike (or power meter) and Zwift, that should show up if you upload the log file to zwiftalizer.com and generate a report. If you’re curious about that I would upload the log from the bad ride and another one from a ride where it worked properly to compare. This is not possible if you run the game on Apple TV but any other platform will provide log files you can upload.
