Hour 40K TT Objective (Indoors)

Hello, hoping you can point me to some literature in this forum, elsewhere, or share experiences that may help me with a new goal, an hour 40K TT.

Looking to use a newly purchased Kickr Core (very excited to upgrade from wonderfully servicing KK dumb trainer), do the mid volume sustained build plan and then the 40k specialty one.

Of course it’s a long term commitment, but a fun goal nonetheless, especially as we sit quarantined at home and without needing to go all aero with the equipment purchases.

Thanks, cheers, stay safe

Since this is done indoors what will you be using to measure the 40km distance?

I was considering a simple magnet speed sensor, as I believe the Smart Trainer could give me speed but would not be accurate in ERG mode (I have to read up on that more).

But I imagine the magnet speed sensor would be fairly accurate, yes?

If your goal is to do a fake indoor 40k TT, you should not be using ERG mode.

Maybe I am reading between the lines wrong?

What is your exact plan?

Apologies, I just realized I wouldn’t have a rear wheel magnet once the Kickr gets here!! :man_facepalming:

Plan is to do Sustained Build and then 40K TT MV Plans.

Maybe before I start and after I finish the above plans I can possibly do a free all-out ride in non-erg mode and see what distance Wahoo app or Strava give me? Is that an option?

Yes, assuming you match the wheel size, you can potentially get live “distance” from a head unit.

Keep in mind that you are totally lacking and real wind resistance and rolling resistance, weight, aero drag, etc., so any “distance” is a guess at best.

Using some of the simulation apps like Zwiift, Bkool and such are somewhat better, since they model some aspects but they are not entirely accurate either.

It all depends on what you really aim to get out if it.

Intent was to change from the current century plan seeing that that might not take place later this summer, explore new workouts in Trainerroad, and in general having the additional metric (speed) and not only watts for pre and post training plans to share with non cycling friends and wifey!!

Just some added inner competition.

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@mcneese.chad, appreciate the feedback as always, and if you know of other posts with other info do share. Thanks as always.

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You might be able to plug something into bestbikesplit.com or other online calcs to figure out the wattage you’d have to push in order to do a 1hr IRL 40K. :man_shrugging:


Yes, I would do practice TTs and final attempt using Zwift or FulGaz or RGT. Not sure if any of these apps have a real-world 40K TT course in the virtual world.

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You can only get your power for a given amount of time. The trainer and computer combo cannot determine your 40k time since your coefficien of drag and frontal area are unknown. If you have your power and time for a 40k you can estimate a new time based on any given power. The speed difference is roughly equivalant to the third root of the new power divided by the baseline power. It is important that your power be determined in the position you TT in. Of course, the estimate assumes identical enviornmental conditions and the same course.

Do the plan as you stated and do your 40k TT on Zwift using one of the courses, maybe Temput Fugo Flats (spelling?) . Turn off Ergo mode. Its about as accurate as you can get without doing it IRL.

Treat the 40k TT as a real life TT race, with hydration and eating on the day. 40kTT’s are a stretch on your physical abilities but are a lot of fun. You learn a lot about yourself.


Could I simply record an indoor ride with the Wahoo app without ERG mode. Of course all variables would be unaccounted for, but it would be just as rewarding as seeing the PR charts on TR go up, to see the speed go up (or time go down for the 40k).

Just load TrainerRoad’s Free Ride 60 minutes and do your 1 hour attempt. Do that more than once and measure gains using average power for the hour. Or load a TrainerRoad TT workout and disable Erg at the beginning of the workout.

Ignore speed unless using an app like Zwift or others already mentioned.


Thanks for the suggestion. I certainly do prefer using watts but it’s just fun to actually see it translate to something like speed or distance. I could use the free ride you mentioned and then simply see the data on Strava/Garmin, assuming of course the data from Wahoo is set up to be transferred in that way. Not looking for something super scientific, but a general idea, just like I know my FTP has increased by x amount (using TR), I know that my average speed has increased by x amount using Strava (outdoors).

Thanks for taking the time and pointing me to the free ride workouts.

Simply put speed doesn’t matter too much. On my Wahoo I only have 3sec power, cadence, and IF, distance. Because you cant hold 40kmhr up a berg. But you can hold 105% over the berg, and down the other side 95% and therefore your at 100%. Thats an example.

When I have done a 40k TT on Zwift, I only look at my power. I have done two. One I went over threshold on the rollers and back down to thshold on the flat. On the descents 90-95%. The other I held a constant power I knew I could do for an hour. The steady state was easier.

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Power over time is King. But you can use the others for fun. As long as you keep your setup consistent you can use speed and distance as pulled from the trainer, in the workout and compare that.

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I learnt that thanks to TR, and it was so satisfying, gratifying, seeing my speed go up in just 6 months of structured training. I would love to see it now after 1.5 years, but unfortunately it’s safer to stay at home.

I’ll keep all the recommendations in mind and find a simple way to tell my wifey that thanks to TR, the second new bike and the KICKR core I got a lot faster… :rofl::love_you_gesture::leg:

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If you can shift your mindset to Power then you may be able to achieve both? You will likely pace your real-world efforts when we get outside again using Power so maybe you can get ready for that in your training.

Adding 50 watts to your sustained 1 hr power is pretty cool and something you could target and celebrate when achieved. This might not be as much an FTP bump, as an increase in ability to express your FTP.

Achieving an indoor 40k TT time target is always going to be contrived. Nothing wrong with it; but it isn’t going to really match what you can do outside with wind and real terrain. That being said, if that is your goal - then use Zwift etc. Zwift will allow you to ride the same course over and over again; but probably always with the same inconsistencies.

If you switch to Power then everything should translate nicely to your real-world efforts outside…

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