Shorter FTP session

I’m new to Zwift having set up my new Tacx Flux 2 yesterday.
What the heck. Today was the day to do my FTP session, the shorter 45 min. Around ‘Richmond’.
Now I’m not unfit. I can cycle a hilly 25 in less than 1hour 40 without too much stress.
My MHR at 66 years is 180.
First time through I got to the 225 W for 2 min and hit a 4% climb and my legs ground to a halt!
Reboot and recalibrate. Same bit, early into 225 W for 2 min and I blow up with heart rate way over 170. Any ideas? I’ve been a club cyclist in past years and an elite runner so pain is no stranger.

The terrain won’t have affected your FTP test, so that 4% climb won’t have come through to your legs. So which part of the test were you doing? If it was the warmup then perhaps your estimated FTP was too high (this is what it uses to gauge the warmup).

Thank you Steve. It did come through the climb in terms of the resistance drastically rising to the point where it overcame my muscle strength almost instantly. I didn’t realise until a few minutes ago that you can lower your estimated FTP. I’ll do that. Someone elsewhere suggested that the test only starts ignoring gradient once you get into the 20 min test session itself?

Gradient is always flat when you are in workout mode (There is on exception but it is not applicable to the FTP test)

You can use the Incline button on the Companion app in the 20 min section to increase or decrease the resistance (± keyboard keys also work and the onscreen buttons)

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Something isn’t right then Gerrie. It was a big increase in resistance above the 225 watts I was already working.
I will lower my estimated FTP and try again when rested.

Do a test with the workout, skip past the first few blocks and go to the one before the 20min section ride that block and when it goes to the 20min section see if you can adjust the resistance,

Thank you. Steep learning curve with skipping and stuff while riding. I need to play with things for a bit methinks.


Peter, resistance in ERG mode increases dramatically if you let the cadence drop. You need to practice the skill of maintaining high cadence when you go to a high power.

Hello and thank you. Maybe that was it. The power figures seemed all over the place. I was trying to maintain 90 to 100 cadence. I’m comfortable with that anyway. It seemed to coincide with the 4% slope. I’ll try to lower my estimated FTP. ERG mode, in fact the whole Zwift thing is new to me. I’m overtraining at the most ment with heart rate up to 150 to 160 on a regular ride. I have a lot to learn including the companion app to control the ride. I’ll rest and then try a ramp test. Peter

Peter, there is an easy way to check it. Your ride will show up in your companion app. Tap on your ride. A map of your ride will open. Swipe the screen over the map of your ride, and you will see the charts of your power, cadence, and heart rate. You can drag a cursor over the charts and read values off the map. The hypothesis which I put forward applies only if your cadence dropped to 50 or so, or below. If it did not, this was not the root cause.

Having said all that, I do not fully understand your description of what happened. You did a ramp test? Steps in the ramp test are 1 min each, not 2 mins, and you do it in ERG mode, so climb makes absolutely no difference. I cannot understand why you say “2 minutes” and make a connection with a climb. Anyhow, it has been my experience that during ramp test that when one reaches the limit of power, one unavoidably drops the cadence, torque increases, and pedaling eventually comes to a halt, i.e., one cannot turn the pedals anymore, cannot regain the cadence because resistance at low RPMs is too high. This is how ERG mode works. And yes, your heart rate becomes pretty darn high at the end of the ramp, when you decide that it is time to quit.

FTP varies in a wide range, but around 180 watts is quite common for people of medium size and medium weight. For professional level female athletes it is common to have FTP in this range, for men it is usually higher. Age pushes FTP down. Two of my friends (in the mid fifties) and my son have FTP in the range of 180 to 200 watts. I am a big guy and I can push close to 300 watts, but my weight kills my power/weight ratio and makes climbs slow. I wonder, what your expectation for FTP was?

Thank you Andrei for your post it is much appreciated. I didn’t save either of my FTP tests as I was disappointed with my failure in both cases.
I wasn’t doing the ramp test but the shorter FTP test of 45 minutes. The stage I failed at on both occasions was in the preparation for the 20 minute effort. It was during the 2 minutes at 225 watts (wattage figure from memory).
Maybe my estimated FTP was set too high? I’ll lower it to 100 and try again.
Expectations? Probably too high. As I said I was an elite runner in my 20s as and 30s. I took to club cycling later in life but was a reasonable TT rider strong on hills. At 66 and with time away from serious training I perhaps need to lower my expectations. I have kept a high MHR of 180 but using Zwift I seem to have it up in the higher region (150+) far too much of the time.
Maybe less than 200 watts at the moment?
I think I need to find a build process. At the moment I feel like I’m pushing too much.

An update. I did the shorter ramp test today. I didn’t finish the 1 min at 230w with my HR up at 175. If I’m honest I could have finished it. But I think 240w for a minute would have been too much.
If I had of realised how FTP is calculated (0.75 of max completed sector) I would have ground it out longer.
So 164 watts. Quite low but room for improvement. I’ve signed up for the FTP booster training plan

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Hi Peter,

Two more notes, from my own experience - perhaps they will be of some use for you, too.

  1. In order to ride at high power, you absolutely need fans. I do not know if you do. When you ride bike outside (or even run, for that matter), you move through the air and get a tremendous air flow which cools you down. At home, if you have no cooling, your blood circulation system works as your cooling mechanism - your heart rate goes through the roof to deliver heat from internal organs to the skin. I run three fans when I am riding above or close to FTP. It makes a huge difference. I would never ever make it through 20 mins at FTP without fans.

  2. You do not necessarily need FTP tests to determine your FTP. I use WKO5 software for that. It costs around $170 or so. It analyzes training files uploaded to Training Peaks (I only have a free version of Training Peaks, which only lets me to store ride data files on their servers for WKO5 import) and calculates my modeled FTP and tons of other parameters. It also makes it easy to track my progress. There is some learning process required to use this program, but there are great tutorial videos from its developers which also cover bike training. There is also free software, Golden Cheetah, which is less sophisticated and less capable and less documented, but it has many overlapping capabilities. It might be able to calculate your FTP, too. Then, all you need to do, is to ride sprints, ride races, especially short time trial and crit races, and your FTP will be automatically calculated. BTW, Zwift also updates your FTP if you ride a race at a higher than FTP power for 20 mins.

All you need, is a realistic number to get started, if you want to do workouts. If you find that workouts are too easy, increase your FTP manually. If they are too hard, decrease it. FTP value is not a badge of honor of some kind, it is nothing but a reference number for you and for Zwift to scale your workouts.

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Hey Peter, you can also do option #3.
Manually lower your FTP to something real low like 100.
Do a free ride on any route in Zwift.
Warm up at your own pace for 10 - 15 min then ride as hard as you can for the next 20 min.
Zwift is always monitoring your performance and if you have a 20 min period of power output greater than your current FTP, Zwift recalculates and auto updates your FTP.

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Thank you again Andrei. I do have a fan running and at a steady power over time my HR rises. I guess that’s to be expected.
I’m presently doing the FTP improvement plan as a way back into the processes. It does seem a little easy and I’m biasing the workouts to 105%.
I’ll complete the plan and try the light ramp test again but this time with the awareness of the .75 x the completed level thing.
At 66 I’m a little nervous when my HR gets up to 175. I’m still not sure what it’ll max out at.

Thank you for that Tim. That is very useful.

Hi @Gerrie_Delport_ODZ ,

I am so interested to see that you can skip workout segments? How do you do that? (I have an Apple TV and use the companion app. if that matters.)


I think you can skip in the companion app. I use Windows and use the TAB key.

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@Beth_Klawun - you can also swipe the segment right on CA (Android at least).

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Thanks @Dean ! That is so handy to know! I can’t wait to try it out! I can’t believe I didn’t know it was possible :woman_facepalming:.