FTP test complete Failure on wheel on trainer

Tried an ftp test today.
Went through the instructions in trainer road for setting up my trainer for the first time. Road for 15 minutes and then calibrated trainer.

As per instructions in info on trainer in trainerroad app I switched to my small 34 tooth front gear instead of my 50 and used a middle gear in the back. (I always have used the 50 until now).

Everything was fine until 350 watts. at that point I was still spinning at 99 ish rpm and everything was going fine although i was breathing harder. Had no issue keeping up with intensity level other than breathing harder.

Problem is my ftp stayed at 340-350 ish and did not keep going up inline with the demands of the trainer. I quit in frustration and bailed on the test? My ftp dropped by 32 points. I just left it the same.

I using a tac vortex smart on a rocker plate and using a tacx trainer tire.

Thx for any help!

I just went down and checked everything out. Just realized my tacx trainer tire is completely shiny and polished. Has little to no grip on it. I think when I run in the 50 and a smaller rear gear the speed or momentum is enough to keep me going against the slippage of the trainer. On small front ring and large rear ring the momentum is not enough and the traction is not enough to keep the test going.

Just ordered a new tire.

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Glad you figured that one out and are sorting the issue now! Best of luck on your next FTP test!!!

Was this a ramp test or the 8 or 20 minute test? With the ramp test on a smart trainer it’s all done in ERG mode but with the 8 and 20 minute tests the test part is free riding mode where you have to change gear and the power output you do is entirely up to you. The ramp test, you just keep going until you fail with the resistance increasing every interval. ERG mode makes the trainer change resistance (or it’s meant to).

Be aware that the Vortex’s are notorious for overstating the power by quite a bit.

It may be that you ran into the power ceiling for the gear that you are in.

The Vortex has a relatively narrow range of resistance that it can generate at a given speed so you should keep to the higher gears to avoid this problem.


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120 PSI, sticky tyre and a lot more roller pressure than you think. Calibrate after 10 minutes and you’re good.
And yes, lower inertia means more slippage, like cycling uphill, unless you follow my recommendation.

This is exactly right.
I had the same thing happen to me last time I did a ramp test. I hid everything, but my cadence, to avoid distracting myself, but at a point I couldn’t help but look, as it felt like the resistance didn’t go up when it should. I felt right, as it was 14 watts below target and couldn’t go higher, unless I shifted to the big ring.

thx guys. Thats exactly what happened. Ill flip up to the big chainring and try again in a couple days. New tire should be here in a couple weeks.