RPM / HIIT trainings

Hi there,

I just went HIIT on zwift and find 110rpm crazy high, especially for those short periods where sometimes it takes 10s out of 30s to detect the rpm increase I do.

At 110rpm my bottom just jumping up and down on the saddle. I might be pedaling wrong or maybe a cross-country hardtail bike is not right sitting position for those rpms. I have correct saddle height, not sure about X axis.

The worst part is that it tells me to go faster, I go faster and the rpm just does not update for few seconds (5-10, sometimes more), but the wattage is skyrocketing.

Then when it updates my rpm its yelling at me to spin slower, than spin faster… then reduce power but spin faster. DECIDE ALREADY.

Its also real hard to find the sweet spot on my transmission for the requested rpm vs wattage.

Then my training fails to meet the requirements for stars…

Anyways, when I tried ERG training, all went good, but find the UI bit confusing and dont know which training are ERG and which are manual transmission trainings.

Not sure if my topic is question or just had to take out my frustration, I leave it as open discussion.

I am using “tacx flux s” as my trainer, cross country hardtail bike with front suspension, flat pedals and random cleanest boots I find at home, weight 98 (mostly fat but also muscle as I work out regular basis 3 times a week, just love eating), for outdoors I have road bike (on it I think it would be easier to go higher rpm)

You might benefit from installing a cadence sensor on the crank arm that measures revolutions.

I dont think thats the case. When I ride connected to my android phone or macbook, I have never noticed that rpm would have issues updating this badly. only when I connect to my desktop. It clearly can update wattage well, the trainer wasnt cheap, it has built in sensor, it should just work… buying new hardware i already have built in does not seem like a solution.

but regardless of that, is there anything I can do to reduce how much I jump on the saddle while riding at high rpm? is there a technique?

Remember that your trainer doesnt actually measure your cadence but rather estimates it (or at least most trainers estimate it - there may very well be some that actually measure it) - so adding a stand alone cadence sensor (which is relatively cheap) would be a good trouble shooting step.

Also, you mention struggling with your “transmission” - assume you are referring to your gearing? If so, this is largely irrelevant as, in ERG mode, the trainer will automatically adjust resistance based on your flywheel speed to maintain the desired power. That being said, many trainers are known to suffer from issues at high flywheel speeds which is why it is generally recommended keep the bike in the smaller ring and middle of the cassette when in ERG mode (to avoid high flywheel speeds down).

Upload a log file to zwiftalizer.com and check if the desktop is having any connection problems with the trainer.

Have you done the same workout on your other devices?

The Flux S does not have a cadence sensor. The Neo 2T does but it’s one of the only trainers like that.

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  1. Don’t worry too much about the target cadence. Pedal as fast as you can as long as you can stay smooth and planted in the saddle. With time and practice you can increase your cadence as the weeks and months go by.

  2. Consider lowering your saddle height by 5mm to 10mm and see if that gives an immediate improvement.

If that describes what I think it does then you probably have little chance of achieving a high cadence and smooth pedalling style. Consider getting advice on suitable cycling pedals for that bike and a pair of cycling shoes.

Edit: what pedal and shoe system do you use on your road bike? Possibly no need for new cycling shoes just pedals.

Yes gearing. The training I went, even when I turned on ERG in popup menu, did not feel difference (only when uphill, but when I went flat and it required me to do higher/slower rpm it did nothing), while on other training, I felt the difference even going flat when it required more watts without higher rpm.

I dont really know which trainings support it or does not support it, I always choose some random training and just go with it. Probably trainings that are not focused on high rpm are the ones that benefit from ERG.

Thank you! Are you sure? Because when I connect the power source, cadence also shows as “connected” to “Tacx Flux 54322” https://www.garmin.com/en-US/p/690888#specs here it also states that it has cadence

Thats something I cannot really afford right now.

On road bike I have flats and just wear flat Vans style shoes. On smart trainer I have a different type bike with also flat pedals.

Most smart trainers (like this one) estimate cadence and transmit that number, but do not actually measure crank arm revolutions. Sometimes they are not accurate, especially in high-cadence situations, or when a rider has an irregular pedal stroke. A real cadence sensor would be installed on your crank arm and measure every pedal revolution.

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as you wrote “crank” i just realised how stupid I am :smiley: makes perfect sense!

po 29. 4. 2024 o 14:43 Paul via Zwift Forums <notifications@gozwift.discoursemail.com> napísal(a):