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So I have ventured in to the dark world of turbo trainers and Sufferfest.
After advice on here (thanks) I opted for a Tacx Flow and I am generally very pleased. However I have noticed that the cadence seems to jump around a bit sometimes on ERG mode when going from lower cadence higher resistance to higher cadence lower cadence resistance and seems to take a bit to work out what the cadence is. I'm assuming that this is because it's calculating the cadence rather than directly measuring it. As such I'm not sure it's accurately indicating cadence.
Anyone else had an issue or tried a stand alone cadence sensor, particularly with Sufferfest?
Also I've noted that I still have to manual go up gears to increase the RPE at higher cadences as it doesn't seem to add enough resistance at 90+ RPM compared to how noticeable more resistance is applied when at 50-60rpm. Not sure if this is normal or I'm just expecting it to be more difficult than it's meant to be. I mean it's still hard but I was expecting it to be even more evil...
Cheers
I haven't experienced the cadence issue on mine, as I use my chainset based power meter for that, but I'd guess you are right - it has to work out cadence from small changes in wheel speed, so it's not going to be that accurate.
Regarding the power vs cadence, relative to my power meter my Tacx Flow under reads (and therefore adds excess resistance) at higher cadences (or over reads a lower cadences, depending on calibration adjustment), which is the opposite of your issue.....Maybe it's just your perception - it's hard to tell without some other power measuring device to compare against.
p.s. the power reading from the trainer is VERY temperature sensitive, so getting an accurate calibration is pretty tricky. You definitely have to do a proper warm up before doing the spin down calibration. Even for significant changes in power during a workout (say switching between 100w and 200w) it takes a minute or so to stabilize as the internal temperature of the trainer changes (as compared to the output of my power meter).
I had a similar issue with my Tacx trainer and TrainerRoad. I bought a Wahoo cadence sensor and it's much better.
The over and under reading of power while in ERG mode is a problem I had with my old Tacx Genius. It’s solved by a beta firmware that Tacx will send you if you mail them and explain the problem to them. I’m on a KICKR now but still have the firmware although I doubt it’s the same as it’s for a different model.
As for cadence I would definitely recommend a separate cadence sensor, given that while using ERG mode on the Sufferfest, cadence is the only thing you have to keep your eye on it’s useful if you are actually getting accurate feedback.
Lastly, you definitely shouldn’t be changing gear in ERG mode, if the trainer is in the process of adjusting resistance then you changing gear is just confusing it and making it more likely that the power setting will be off or take longer to settle. If the workout has odd changes in power and cadence, like a recovery interval of low power at high cadence straight into a high power/low cadence climb then it can take the trainer a while to work out what’s going on, I find it works better if you pre-empt the start of an interval like that by adjusting your cadence in the couple of seconds before the change.
#EDIT: oh and if you are using ERG mode then the RPE number is meaningless as it’s a metric for using in either level mode or a dumb trainer. Have you done an FTP test or the Sufferfest 4DP test yet..? If you haven’t then the app doesn’t really have any idea of your fitness level and is just working from whatever the standard baseline is which sounds like it’s too low for you.
Thanks for the info, all very helpful.
I actually have a Wahoo Cadence sensor which I used on my old 'dumb' turbo trainer before I got the Tacx this week. I'll using that a go in place of the inbuilt cadence sensor, though I assume that will take the place of both the inbuilt speed and cadence sensors on the Flow?
I've done a 4DP fitness test so theoretically is should be working to my (un)fitness level. I was assuming the RPE would still be a rough indicator of how much I should be suffering.
I'll try the standalone cadence sensor and see how that goes with the ERG and just pick a middlish gear and let it do its thing.
Cheers all.
I think your speed still comes from the trainer, there is a wheelsize setting on the sufferfest app to make sure it's calculating right but to be honest speed isn't really a meaningful metric on a smart trainer as you could be spinning a 53/11 for a whole session if you wanted and have done the whole workout at 45kph whereas if you do it in 34/28 then you'd only have been doing 19kph but because of ERG mode the workout would have been the exact same as far as you are concerned.
The Sufferfest videos can be a little disconnected when using a smart trainer, the onscreen instructions and RPE figures can often indicate you should be trying much harder than the ERG setting will allow but the power output is all calculated to maximise what you get out of it based on your 4DP numbers so I find it's best just to stick to the required cadence, let the power sort itself out and not worry too much that the onscreen instructions are telling you to sprint until your eyes bleed.!!!
The cadence sensor on my T2240 (Tacx) was very intermittent on zwift / erg mode, so switched to using my Wahoo SC instead and it’s been fine since then. I then added an ANT+ dongle as the Wahoo emits on Bluetooth and ANT+, so that I could use Bluetooth for other devices.