Non-Smart Trainer Issues or Just fatigued?

Hi Guys,

Wondered if you could help. I have been on trainerroad for about a year now on a non-smart trainer. What I have noticed is if my bike sits on the turbo for a number of weeks the FTP is the same (even increasing over a week, so I increase the intensity) however from time to time, after using my bike outdoors, when I put the bike back on the turbo my FTP drops massively by 30 watts plus. Annoyingly I have to use the same bike for outdoor rides. Even if I was severely fatigued I cant see my FTP dropping that much any ideas? Or could it be case of I hit it too hard last week? Last thing I want to do is drop my FTP and end up working in zone that don’t encourage adaptation

For completeness:

  • I have a seperate wheel for indoors and outdoor rides
  • Tyre pressure generally remains the same (plus or minus 5psi - shouldn’t make that much difference?)
  • Training time is the same each day
  • Nutrition is the same for each ride
  • Resistance setting is the same for each ride
  • Same temperature conditions (albeit varying a few degrees)

Towards the end of last week I felt great did a long ride on Saturday then had Sunday and Monday off before start this weeks rides on Tuesday. However, the FTP from last week was way too hard, I was hitting my max HR in the warm up. I reduced the intensity but even in the recovery valleys my HR was in the sweetsport zone. I tried again today but I was at least 40 watts off last weeks numbers (my FTP is 225, so this as a percentage change seems to much to be fatigue)

Or am I just physically too cooked? Even through mentally I feel fine. Sleep is good, appetite is normal.

Any pointers would be great, aiming to get a smart trainer in the black Friday deals to at least remove some variables from training as this swing in FTP is both annoying and frustrating.


A couple of questions:

  1. Are you using a power meter on the bike (for power data inside and outside), or Virtual Power (estimated power for inside only)?

  2. What trainer are you using?

  • If you are using Virtual Power, this is a problem. You must maintain a more consistent tire pressure to maintain consistency in the power estimation. A 10 psi swing is enough to really change the Virtual Power data.
  • Coupled with that, the roller pressure against the tire must be done with equal attention. If this is not set the same from workout to workout, you will experience different feel for the “same power”.

In case you aren’t familiar with the VirtualPower:

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Thanks! These are helpful points.

Unfortunately no power meter, so can’t use that as a frame of reference. So only using virtual power.

Trainer is the tacx blue matic. Its quite old about 7 years.

I replace the outdoor wheel for my dedicated indoor wheel. And generally keep on top of the pressure. Could this be the cause of a 30 watt plus difference? conversely after pumping them up give me a gain, but this rarely happens.

Roller pressure is constant I generally double check this.

Was just wondering if its anything major. I’m more inclined to think my issue is trainer based given the number of variables rather than fatigue.

Yes, for Virtual Power, this is SUPER important. In short, Virtual Power takes your wheel speed and known trainer (as entered into the app) and converts that to an estimated power.

  • If you removed the pressure entirely, but still pedaled it, you would be getting power data, because of the wheel speed. This would of course be totally inaccurate.
  • That is an extreme example, but meant to show that wheel speed is the way the app estimates power. So having very consistent bike tire pressure and trainer roller pressure is essential in giving you worthwhile data.

Until you make a serious effort to control those settings, that is in question, IMHO.

Ahhh thanks, yes got a track pump so ensure that this is accurate.

And yes I make sure the resistance level is the same before each ride as it can slip from time to time.

Might just be best to do endurance rides until the end of november help develop a wider base until I get a proper smart trainer. Really helpful pointers though thanks Chad!

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Having used virtual power with my KK Road Machine for a lot of years before getting my Assioma pedals, as Chad mentioned tire pressure and resistance against the tire is of utmost importance for keeping things consistent. I pumped my tire to the same pressure before every ride and used a piece of tape on the knob to know how many turns I was making on it (and backing it off) to make sure it was the same every time.

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So I guess the more you loosen the high the power goes up?

Yeah, since virtual power is all based on speed vs. the resistance curve of your trainer. With less resistance you can pedal faster, easier (or conversely, with more resistance it would be harder to get the speed up).