Confused about TSS score and potential FTP discrepancy between indoor and outdoor

Monday, 3 June 2019
2:47 PM

I have been cycling seriously for about 15 months now and have decided to take my training to the next level. I’ve joined TrainerRoad and am in the first month of training indoors and never owned a smart trainer.

I am really confused with my situation at the moment which I think stems from the FTP that I was assigned after completing the ramp test which I did twice. The first ramp test completed at 246 and the second attempt was 250. Subsequently, I set my FTP at the second value and have been completing workouts successfully.

My confusion comes from the TSS that I seem to be accumulating within the TR calendar from week to week as I do a lot of outdoor riding where I’ve had my FTP set at 270 within Strava and that has yielded TSS scores of 600 - 700 from week to week. However now my FTP is set at 250 I am accumulating TSS in the realms of (700 - 1000) from week to week. I really don’t think that it is possible to accumulate that amount of TSS from week to week without digging a fairly big hole for myself so something has to off in my opinion.

I did complete Palisade on the weekend and whilst it was hard it was manageable so I tend to think that my FTP on the trainer is correct but I feel that there seems to be a large discrepancy between my indoor FTP and outdoor FTP which is giving me values for TSS that would be far greater than my body would allow? Does anyone else have any thoughts on this?

I want to say thanks to everyone for creating an awesome environment in which to learn and become faster.

1 Like

What’s the confusion?

If your FTP on Strava and outdoor is set to 270, you’ll get XX TSS for a given ride. For the same ride w/your FTP set to 250, you’re going to get YY TSS, i.e., YY > XX

Set your FTP to the same value everywhere (e.g., TR, Strava, headunit, etc…) and you will not have this problem.

Thanks Kickrlin, well that is what I was thinking but my confusion is around why my two ramp tests gave me a result around 250W. I am not hung up on the TSS value so much but moreso the reason why. My main concern is whether I can sustain a workout at the 20W increase. Given that I am new to indoor training I thought that it would be best to go with the value that came from the ramp test.

I’m assuming you did a test outdoors to get 270W?

In theory, you take your 250W FTP test result and start a plan or do some workouts. If after a few workouts, you think that it’s too easy or too hard, you can manually adjust your FTP up or down. As for the 20W discrepancy in FTP, this could be due to any number of reasons. For example: you had a bad day, inadequate cooling, etc… There are entire threads/conversations on this forum about the various FTP tests, which one is better, indoor FTP vs outdoor FTP, indoor hungover sick FTP vs outdoor uphill FTP, etc… I’m joking but not as much as you might think.

Again, feel free to manually bump your FTP. If the workouts get too difficult, then you’ll know you need to drop it back down. Note, the goal is not to push yourself to the brink of failure every workout.

For various reasons you might have a higher outdoor FTP. I spent a few months ignoring my ramp results and stuck with my outdoor numbers, this was an error. Sweet spot workouts were more like Threshold, Vo2 workouts failed and so on.

I also learnt this week that you can edit the FTP on individual rides once they are synced from Strava. Perhaps setting these to 270 once imported will give a more accurate weekly TSS value?

1 Like

Couple things factor into different outdoor and indoor FTP

  1. the psychology of it. until you get your music/entertainment dialed. and you’re both used to effort and buy into suffering without any distraction, it is much harder to sustain effort indoors.
  2. There is a difference in feel between the inertia of a trainer and outdoors, and just like how you can get better at putting out power on downhills, you’ll also get better at putting out power on a trainer.
  3. most importantly: cooling. If you’re overheating, you might not even realize it with a big fan and AC going, but its hard to get right. i have two Honeywell Turbo Force fans going, at a roughly 33 degree angle near my front wheel (angles are better than straight on) to maximize the surface area of my body getting hit, and this feels like the bare minimum to me. I’ve been considering getting a or similar directional pivoting ‘blower’
  4. i dont know much about smart trainers since i dont have one, but if that thing is recording power, i always hear people talk about power match, so you have to make sure you’re seeing the same power meter data indoors and outdoors.
1 Like

Kudos to you @AdamB for climbing the mountain without a top! I, like you, have been ramping things up. Love data, love numbers, love seeing them paint a picture of improvement…hate when the numbers aren’t the same across apps. Ramp tested this morning @276w. Been using a PowerTap g3 hub power meter outdoors for a few months now. TrainingPeaks (free version…also use Elevate in Google Chrome) has me at 308w. So now, once I finish a TR ride, I hop over to TP and edit up the TSS to match what TR wrote over to Strava. When I do an outdoor ride, I hop over to Strava and edit down the TSS to match TR. First full season of structured training…so still learning lots.

Firstly, I would like to thank everyone for their insightful comments, this forum and community rocks!

So I have only owned my smart trainer for 3 weeks but have trained with power for the past 12 months. I have a stages power meter on two seperate road bikes and use that for outside rides. Going back to what @KickrLin said earlier, tonight I decided to bring up the devices screen within TR app and pair both my Tacx Neo power and the stages power meter. I rode for 5 minutes and there seemed to be a fairly big discrepancy between my stages power meter and the Tacx Neo power meter, yep you guessed it, about 20 - 25W. I then calibrated the stages power meter within TR and rode for another 5 mins and again the stages consistently reported 20 - 25W above the Tacx. Admittedly this is a fairly rudimentary way of measuring the difference in power between the two devices but it was all I had/could think of. I decided to see what Zwift reported so I paired the Stages with Zwift, then used the iPhone Tacx App to report the power from the Neo and got exactly the same result, 20 - 25W difference in power at any point in time.

Over the past 3 weeks I haven’t paired stages with TR and used power match and maybe that is my mistake but I wouldn’t expect to see such a large discrepancy on power numbers from the Stages to the Tacx Neo. To make doubly sure, I decided to remove the crank arm and put the second stages power meter on the trainer bike and got exactly the same result again. Whilst this hasn’t affected my training at all because the baseline has always been the same its annoying and I probably should go back to Tacx to ask them why. Thanks everyone for your assistance and apologies for asking some newbie questions!

I would say you probably lose a few watts for drivetrain losses. Then, let’s assume your left leg is stronger than your right, i.e., you’re not 50/50 balanced. The Stages doubles whatever it sees on the left crank and that gives you your power number. If your left is stronger say 3%, then after doubling it you have 6%. At 200W, that is 12W. At 300W, that becomes 18W. :man_shrugging:

Personally, I would use the Stages for power and PowerMatch to allow TR to control the ERG. You ride outside w/the Stages. By riding inside w/it as well, you know your power numbers have the same meaning.