Converting smarttrainer/TR FTP to outdoors

I apologize is this has been addressed elsewhere in the forum, but I am a newbie to TR. With the use of my indoor Wahoo Kickr and TR, I have my FTP. Looking ahead to next summer’s racing season, I was curious how to extrapolate that information to outdoor racing, without the use of a power meter on my bike? I might buy a power meter eventually, but not for now. For a 70.3, I read that I should target between 77-80% of my FTP during the cycling portion of the race. Without a power meter during the race, should I see what my average speed is on my bike when cycling at 77-80% of my FTP threshold when cycling indoors on my Wahoo, and use that as my target during race day? Thx!

  • Absolutely not (to the bold above).
  • Speed on a trainer is just short of meaningless and should be avoided in this context.

Without a PM, my instant answer is to get REALLY FAMILIAR with your RPE (Rate of Perceived Effort / Exertion). Learn how hard you feel in each of your workouts. Pay special attention to the ones that are at power and effort levels around what you expect on race day. Take that perception with you on race day and race by feel, not numbers. This is a likely inflammatory stance in this group so focused on numbers, but I think there is real value in learning and adjusting by feel.

Power meters can fail, speed can be a faulty metric if winds are different than expected, and other things can throw off our “perfect by the numbers race plan”. As such, I spent the last 3 seasons focusing on the numbers in training, associating them with my efforts and doing my best to apply them via RPE outdoors. I did this for all my Duathlons (bike leg specifically) even though I actually have access to power on the bike.

All that said, the other option you can consider, if you really want numbers, is to use something like Best Bike Split. You can enter you and your bike data, the course, and it will generate a pacing plan. You can even dump it out based on speed and use that instead of power.

You would still want to consider how much “extra” power you would have being outside. Without a power meter and testing, you will have to guess, but that might be OK if you are conservative. Many people use and like the function of of BBS to get a good race plan.

i’d just pace based on HR/RPE with lack of a PM

If you don’t have one already, get a heart rate strap now, use it for every workout and get familiar with your HR vs power. HR has some limits but it actually can work pretty well for pacing steady state efforts.

Speed sucks as a pacing tool unless you are on a pan flat course with no wind. (And unless your on an indoor velodrome, there will always be some wind). Of all the pacing tools (power, HR and RPE) speed is the worst choice as speed vs effort is not a consistent ratio. If you don’t have a power meter, heart rate informed by RPE is the next best pacing tool.

Thank you for the suggestions!