Getting a steady power reading in Zwift
Discussion
Hey all, I use Zwift with a Wahoo Kickr for indoor training to supplement my outdoor riding. I have noticed that my wattage reading during free rides is all over the place; if I'm riding a flat road with 0% gradient, at a constant cadence, my wattage seems to bounce up and down. It might go from 260, to 180, to 220, to 170, to 200, all within a few seconds and not with me feeling like I'm stabbing a the pedals - I try to deliver a smooth stream of power from each leg to keep the pedal strokes even. After the session, I'll get an average wattage reading of 200 watts for example, pretty much in the middle of the fluctuation range however the power graph shows the second by second peaks and troughs similar to what I see on the screen.
Is this normal for free rides, IE not a workout session and not having ERG mode activated? I don't struggle with workouts with the ERG mode activated, if it tells me to hold 300 watts for an interval, the Kickr locks the resistance on so I can't exceed the power it sets and my power graphs are smooth at the end of the workout, showing I held the power consistently with no spikes or dips in output over the intervals.
I did do some troubleshooting; I disconnected all bluetooth devices and plugged the Kickr into my laptop with an Amp+ connection to make sure bluetooth dropout or interference wasn't an issue. I tried setting the power readout to 1 second average or 3 second average, the power on screen changes roughly once per second regardless, however this setting just seems to change the amount of time the power is being measured over, not how often it updates on screen. It didn't make much difference to my fluctuating power reading in the 3 second setting.
My dad uses my Kickr with his Zwift account on his iPad and he thought the power reading looked odd, however he only uses ERG mode for workouts and virtually never goes on free ride mode. I logged into his account on his iPad and went for a free ride and the spiky power output was there on his account, so it's not an issue with the settings on my personal account being different to his. Unfortunately he's got a back injury so he couldn't jump on and see if he could recreate the issue, but he did acknowledge that my pedaling action looked smooth.
It's a 6 week old Kickr of the latest model type and the firmware is up to date. My Zwift app is on the latest version. As I say, in ERG mode it works perfectly. Perhaps this constantly fluctuating power display is normal when free riding without ERG or a structured workout in progress? I am a fairly new cyclist and while I can hold a steady cadence without issue, could there be some sort of technique issue on my end? I try to keep my pedal strokes smooth and consistent, like two spinning wheels, rather than stabbing harshly at the pedals as I alternate legs, but perhaps I'm not as good at this as I think. Is it possible to hold a steady cadence but deliver too much force at one point in the pedal stroke, possibly upsetting the machine?
Maybe it's just how it is, but it would be far more useful for training to understand the power I'm putting out rather than trying to guess based on the rapidly changing number on the screen and then reviewing a spiky power graph after the session.
Is this normal for free rides, IE not a workout session and not having ERG mode activated? I don't struggle with workouts with the ERG mode activated, if it tells me to hold 300 watts for an interval, the Kickr locks the resistance on so I can't exceed the power it sets and my power graphs are smooth at the end of the workout, showing I held the power consistently with no spikes or dips in output over the intervals.
I did do some troubleshooting; I disconnected all bluetooth devices and plugged the Kickr into my laptop with an Amp+ connection to make sure bluetooth dropout or interference wasn't an issue. I tried setting the power readout to 1 second average or 3 second average, the power on screen changes roughly once per second regardless, however this setting just seems to change the amount of time the power is being measured over, not how often it updates on screen. It didn't make much difference to my fluctuating power reading in the 3 second setting.
My dad uses my Kickr with his Zwift account on his iPad and he thought the power reading looked odd, however he only uses ERG mode for workouts and virtually never goes on free ride mode. I logged into his account on his iPad and went for a free ride and the spiky power output was there on his account, so it's not an issue with the settings on my personal account being different to his. Unfortunately he's got a back injury so he couldn't jump on and see if he could recreate the issue, but he did acknowledge that my pedaling action looked smooth.
It's a 6 week old Kickr of the latest model type and the firmware is up to date. My Zwift app is on the latest version. As I say, in ERG mode it works perfectly. Perhaps this constantly fluctuating power display is normal when free riding without ERG or a structured workout in progress? I am a fairly new cyclist and while I can hold a steady cadence without issue, could there be some sort of technique issue on my end? I try to keep my pedal strokes smooth and consistent, like two spinning wheels, rather than stabbing harshly at the pedals as I alternate legs, but perhaps I'm not as good at this as I think. Is it possible to hold a steady cadence but deliver too much force at one point in the pedal stroke, possibly upsetting the machine?
Maybe it's just how it is, but it would be far more useful for training to understand the power I'm putting out rather than trying to guess based on the rapidly changing number on the screen and then reviewing a spiky power graph after the session.
Ah that makes sense. Glad I don't have it set up wrong or a faulty device, or worse, awful pedaling technique.
I wish there was a way to get a smooth readout in free rides, but I suppose I'm probably best off developing my "feel" for power anyway since I don't have instant power data to look at while I'm outdoors on my road bike. I need to get used to feeling how hard I can push and knowing how and when to deploy that on the road.
I wish there was a way to get a smooth readout in free rides, but I suppose I'm probably best off developing my "feel" for power anyway since I don't have instant power data to look at while I'm outdoors on my road bike. I need to get used to feeling how hard I can push and knowing how and when to deploy that on the road.
Also, it seems the actual gradient is measured/delivered more finely than whole numbers... at least one decimal place... so "0%" could really be -0.9% to +0.9%, with your legs adjusting to the effort as your trainer adjusts.
And notice that from 3% upwards (maybe 2%?), the colour of the figures changes - 3% can be yellow or orange; generally (but not always) when it's orange, it'll go to 4% on the next bit.
I've seen people on the forums noticing that holding a set wattage on a set gradient doesn't give a constant speed hence the decimal point assumption on gradient; the colours are just what I've noticed (fairly new zwifter, on Lv16).
And notice that from 3% upwards (maybe 2%?), the colour of the figures changes - 3% can be yellow or orange; generally (but not always) when it's orange, it'll go to 4% on the next bit.
I've seen people on the forums noticing that holding a set wattage on a set gradient doesn't give a constant speed hence the decimal point assumption on gradient; the colours are just what I've noticed (fairly new zwifter, on Lv16).
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