FTP Test - A Case Study

Hi All,

Can you help me assess the ramp test below? My wife did it today and she was able to go up from 111 to 121 watts but i’m confused with the final part of the test.

Towards the end of the test her power started to drop but her cadence kept in the same range for about 4 minutes before she decided had to stop. I was with her and she started telling me it was really difficult but she looked in good shape so i told her to keep pushing until she couldn’t pedal anymore.

What looks curious to me is that I would never be able to keep cadence for so long with the power dropping like that. In my case, it is be a matter of seconds for a full stop once I’m done with the test with both power and cadence dropping really fast but, that’s really my n=1 experience and it may work differently for others.

Does this test profile looks normal to you? It was done on a Tacx Vortex.

Looks like a normal ramp test to me.

Your wife seems to quit slower than most people. You probably already knew that.


Not sure if this was on purpose, but once she couldn’t hit the power target at 22:00 I would have stopped. Not sure if this is a trainer ceiling/floor resistance issue, but I don’t think ramp tests should look like this at all. The “don’t stop until you can’t turn the pedals anymore” thing presupposes you’re hitting the power target. It’s a nice extra vo2/threshold interval, but seems like some power was held in reserve.

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That doesn’t look right to me as once you can’t do the work anymore the power curve drops off sharply and your cadence drops because you can’t pedal anymore.


Hitting a power ceiling could be happening on the vortex. You could test it by using the same gear and cadence when fresh, and see if you can get to a higher power.

It could also be an erg mode issue where it just stops following the demand power - I’ve had that in a ramp test. If you have erg mode issues with other workouts, that might have happened.

Third possibility, am I right in saying that your wife is quite new to this type of training? Maybe she wasn’t actually near her limits, and that produced the odd result.


So I didn’t want to jump to conclusions before getting some replies but my impression is that the trainer had Something going on the erg mode that allowed her to keep pedaling at a power lower than the target but I didn’t know if this could be some type of feature to keep people from going to an all stop or a failure in the system.

The cheaper trainers often have power ‘floors’ and ‘ceilings’ - there is a power range for a given gear that you can’t get out of, you’ll have to shift to get higher or lower. I know I often have to shift between work and recovery intervalls, because I can’t drop as low as the recovery wants, or I can’t get up high enough in the work intervalls.

I think it has more to do with fly wheel speed and the resistance unit being limited than actually being a feature.

I shift up once roughly about my current ftp during the ramp test, that should be enough to make sure I don’t need to shift in those last minutes.

I’d ask her to start training with that ftp though, to see how hard the workouts feel, but also to see if erg mode misbehaves during any other workouts.

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Yep, until recently, I was training on a Vortex. The power ceiling when in the small ring with a slow cadence is around where her power started dropping.

To get the advertised 950+ watts you have to be in the big ring + the 11 tooth with a cadence of about 120+.

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Which gear? At one point the vortex won’t go up or down in power anymore unless you change gear in erg.

But her power drop was way below 950W, more like 150-160W. Wouldn’t have thought that would be a limiter even if she was in bottom gear with low cadence. Unless she’s riding a gravel bike with a cassette that goes up to 50T or something!

There is a top/bottom limit for every gear. Someone on here made a chart, but for a different trainer. She must have started in a very low gear because her low previous ftp, which made the ramp start at about 60W? There could well be a 160W ceiling for that gear.

Indeed, she would have hit the power floor of the Vortex on the big ring at 60 watts in all of the reasonable rear gears. It’s really sensitive to flywheel speed.

My recommendation for that specific trainer would be to do workouts in the big ring and whatever gear in the rear that makes the chain not angle much.

That should remove the power ceiling for anything but all out sprints and improve the road feel (the flywheel is very small so spinning it faster smooths things out).

The downside there being that recovery intervals will need a gear shift to avoid the power floor. The trainer does get somewhat loud when spinning fast.

However, it’s a good trainer for the money IMO and I did not regret the purchase. It’s now a dedicated trainer for my wife’s bike.

This is what my (currently only) ramp test looks like

It was done on a Minoura “wheel on” turbo so there’s a bit of variance in the moment to moment power but the important thing is that at the point of failure my performance simply falls off a cliff which the TR app then sees as me “failing” and brings forward the recovery portion of the workout.

Perfect example of how the ramp test should look above ^^^^^

I didn’t think about relation between gear choice and ERG mode on cheaper smart trainers but if that was the problem don’t you guys think that the power would remain on the same level instead of dropping like that?

It is dropping when her cadence drops. I think she is done at that point, and should have just stopped.

I think she is hitting the power ceiling three steps before the gradual drop in power. That step still looks ok, the next one, she is raising her cadence for a bit to meet the power target, eases off for a few seconds (there’s an obvious dip in power and cadence), the raises it again and meets the demand power. Then for the next step, she can’t make demand anymore, and is staying on the power from the previous step for about 40s, before gradually slowing, with the gradual decline in power.