Trainer power and target race power

Aug 16, 17 6:05

I know I've seen a few threads in the archives discussing the differences between power on the trainer compared to out on the road. Seems like it's fairly common to see lower FTP numbers indoors, or at least the RPE for a given power is tougher indoors for many compared to being out on the road. This is something I've seen myself. A lot of those other threads really discuss what the causes might be, etc.. I know the difference (if it exists for a person) is also variable depending on the trainer, the conditions of the room, etc..

My question really revolves around game-planning a race when the only "consistent" power files you have are on the trainer. I've only done sprints and oly's and looked at my power, but didn't' really have a firm target. It was a lot more feel. Now that I'm moving up to half distance this year, I'm starting to try to settle into my target numbers (10 weeks out and will probably try to test again 3 weeks out from the race). I see people saying they shoot for 75% FTP on a full course or maybe 80-85% for a half (again I realize this will vary and is a loose rule of thumb some may use). Are you all basing that off of say a 20 minute test on your trainer?

My power numbers aren't anything special. I should be testing around 200 right now on my trainer (been several weeks). Doing a 2x20 at ~180 is a tough workout (these numbers are depressing for me, haha). But then I go for an outdoor riding at 180-200W just doesn't seem very tough at all. My NP for a 3+ hour medium-effort ride is ~180, but there is a lot of stopping, slowing, etc.. I just don't have a lot of opportunity to get a long consistent ride to confirm that my outdoor FTP is in fact higher. But from RPE, I'd say I'm about 20-30 watts different.

Anyone dealing with limited outdoor data experiencing the same thing? I know my solution is to get a rough estimate, then base off feel to fine tune. But it's my first 70.3, and I just want to get a respectable bike and run in (at least respectable for myself). I don't want to blow up on the run or leave too much time on the bike if not necessary.

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Re: Trainer power and target race power [KG6] [ In reply to ]

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exxxviii

Aug 16, 17 6:16

Post #2 of 14 (1375 views)

I did my first HIM (actually my "first" triathlon) last year. First is in quotes, because I did some triathlons over 25 years ago, but I had been off the bike for 25 years. So, it felt like a first all over again.

I did, and still do, nearly all my training inside. I may get out twice a month for an outside ride.

Anyway, my very first, I rode to RPE based on the virtual power numbers from my Kirt Kinetic trainer and how that compared to outside rides. External race factors aside (30 MPH headwinds on the first half), my ride and run were much better than expectation.

Second tri was another HIM, but I had a PM by that time. I targeted 80% FTP based on my FTP tests from everything indoors. I only vetted that target by doing some outdoor rides leading up to the race, but it was just for comparison and confirmation. Again, my run was good, so the ride seemed to support a solid performance. I did another HIM this year with the same target and I got the same results.

Between the HIM races, I did a few sprints targeting a little over 90% indoor-measured FTP, and those runs were all solid. I would have liked to have been a step or two faster on the runs, but I cannot complain that much. I am not gutsy enough yet to go for 100% FTP on a sprint to see what happens to my runs. Maybe later this year.

So, my conclusion is that I am entirely satisfied using my indoor-tested FTP results to set targets for my races. This has worked for me very well, and I did some 60 mile to 80 mile outdoor rides in the weeks leading up to the HIM to validate my FTP target and how that felt in real life.

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Re: Trainer power and target race power [KG6] [ In reply to ]

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longtrousers

Aug 16, 17 6:44

Post #3 of 14 (1334 views)

Out of own experience and what I here from other people: a half-distance as a beginner is more like a full distance what intensity is concerned than an olympic. As a very experienced athlete you race a half distance like an olympic one.
And as a beginner your olympic intensity is a lot lower than as an experienced athlete (as a beginner I started getting slower in an olympic after 30 km).

Don't know if this helped you, but to calculate a certain power from an ftp test could go wrong if you're not very experienced.

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Re: Trainer power and target race power [KG6] [ In reply to ]

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nc452010

Aug 16, 17 6:57

Post #4 of 14 (1319 views)

I don't accept your premise that FTP #'s indoors are less than outdoors #'s. I think it may be for some.....in some situations. I also think it's higher for some....in some situations.

I would never, ever race to a targeted FTP %-age that I gleaned from only indoor testing.

YMMV

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Re: Trainer power and target race power [longtrousers] [ In reply to ]

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KG6

Aug 16, 17 7:01

Post #5 of 14 (1316 views)

Quote:

Don't know if this helped you, but to calculate a certain power from an ftp test could go wrong if you're not very experienced.

There's not doubt this is a factor I'm taking into account. I plan to be on the very conservative side due to inexperience. But I'd hate to do the whole ride ~30 watts lower than I could actually be doing just because it's ~30 watts harder on the trainer (this would be on the extreme end). I also know I will need to adjust based on RPE and don't expect to get it perfectly my first time out. There's a reason experience is so valuable. But I also know that my lack of experience is going to make my RPE not quite as valuable. What feels easy in mile 15 won't necessarily feel the same way in mile 50 with a run to follow, so just trying to be as prepared as one can when I don't have any personal experience to fall back on.

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Re: Trainer power and target race power [nc452010] [ In reply to ]

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KG6

Aug 16, 17 7:14

Post #6 of 14 (1295 views)

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don't accept your premise that FTP #'s indoors are less than outdoors #'s. I think it may be for some.....in some situations. I also think it's higher for some....in some situations

I feel I addressed this in the first post and can agree. I think your FTP has a lot to do with the course and how the power has to be put through the pedals. An uphill course will yield different results than a downhill, etc. Not all trainers are the same. Flywheels will play a huge roll, etc.. Some may have a setup that allows them to do better indoors. I actually probably do better indoors than going out in the 100F mid day heat right now. But typically, compared to say 75-80 F outdoor morning rides, my indoor rides are much tougher from a body heat transfer perspective (even with my blower fan in my face, I can soak a towel). And my cheap trainer and it's tiny flywheel most certainly have a different momentum profile throughout the pedal stroke than riding outdoors.

This was more about utilizing your power numbers during a race when you only have that indoor info (not trying to dig too deep into the indoor vs. outdoor differences and if/why they exist). I've been using power to gauge my workouts and that's been a great help. Now just trying to best use it for the actual race.

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Re: Trainer power and target race power [KG6] [ In reply to ]

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wcb

Aug 16, 17 7:20

Post #7 of 14 (1289 views)

KG6 wrote:

Trust me - you'd rather be 30 lower than 30 over. ;-)

Typically I use my trainer FTP. I'll do a handful of long outdoor rides leading up to race day to really dial it in and confirm. Keep in mind you have a swim prior that can impact your ride somewhat.

Lastly, I've started monitoring both power and HR when racing. Power is my primary but HR is definitely secondary. If it's hot or humid your HR can easily go +10 over normal at the same power. I've gotten into situations where I just couldn't get my HR down on the run because I pushed it too hard / too long on the bike (140.6 distance) while hitting my power numbers. Now days if I see that happening I'll dial the power back a bit.

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Re: Trainer power and target race power [nc452010] [ In reply to ]

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atxtri1

Aug 16, 17 7:29

Post #8 of 14 (1272 views)

nc452010 wrote:

I don't accept your premise that FTP #'s indoors are less than outdoors #'s. I think it may be for some.....in some situations. I also think it's higher for some....in some situations.

YMMV

I think you'll see a lot of this. I have found that my outside riding reflects a little lower FTP that I train to indoors. Based on that, I don't necessarily race on a particular % of an FTP that was determined indoors. In fact, and not saying this is the best approach, I train on Power, but race on RPE with my power #'s to guide......rarely looking at my numbers during a race.

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Re: Trainer power and target race power [KG6] [ In reply to ]

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TennesseeJed

Aug 16, 17 7:37

Post #9 of 14 (1252 views)

If you think your FTP is 200 based on a 20 trainer test then use that number for your power targets in training. Then use your training data and race simulations to determine your race power. Your trainer FTP is a valuable metric in ultimately arriving at your race power but it is not the only data point.

10 weeks out from a 70.3 you should probably be doing some longer rides outside in the near future. Start those rides with long intervals at say 80% of your FTP, or 160 watts NP. You may start doing only 90 min at that power, but I suggest building up to the full 56 miles at that power over the course of your training. During these long rides, you will learn whether or not you can handle 80% for that long, or whether 80% is too low. Keep adjusting that number until you land on a number that you know you can sustain for 56 miles and still run afterwords.

Throughout training, do a couple of race simulations at what you think your race power is and go run 5-6 miles at race pace afterwords. How did you hold up on that run? If you held up well, you likely have the power number right. If you fall apart 3 miles in, you are over-biking.

The point is your race power should be determined based on a variety of factors. You are right to not take 80% of your trainer FTP as gospel, but differences in outdoor and indoor FTP are not the most relevant factor for a 70.3. Some people have really good muscular endurance and can run well off a .9 IF over a 2 hr bike, and other people struggle to run off a .7 IF over a 3.5 hour bike. It is not easy to do, but during training you should be training your body to hold a high IF over a 56 mile bike while learning your limits to ultimately arrive at your target race power.

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Re: Trainer power and target race power [KG6] [ In reply to ]

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nc452010

Aug 16, 17 7:38

Post #10 of 14 (1252 views)

KG6 wrote:

How could you trust any data that hasn't been gleaned via a repeatable method? Do your test on the same stretch of road, every time. As much as possible, try to reproduce the same EVERYTHING (external factors). Anything less, and I don't see how you could rely on it.

Let me ask.....why would you NOT test outdoors......if that's where you're going to be racing?

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Re: Trainer power and target race power [KG6] [ In reply to ]

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exxxviii

Aug 16, 17 7:39

Post #11 of 14 (1246 views)

KG6 wrote:

I'd hate to do the whole ride ~30 watts lower than I could actually be doing just because it's ~30 watts harder on the trainer (this would be on the extreme end). I also know I will need to adjust based on RPE and don't expect to get it perfectly my first time out.

Realistically, if there is a difference, it is likely on the order of 5W - 10W from your optimum rather than 30W. The key is to use your FTP that you have been training against inside. Then, use outside rides at your HIM target to verify and validate the target. Look at your HR and consider your REP while riding outside at 70% to 90% of your FTP based on your indoor 200W FTP test. Compare that HR and RPE to your HR and RPE while riding inside at similar power levels. You may find that you can push a little higher, but it would probably fall on the order of 10W higher, as you observed below.

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Re: Trainer power and target race power [nc452010] [ In reply to ]

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KG6

Aug 16, 17 8:03

Post #12 of 14 (1210 views)

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To address the first part, I guess that's kind of the point. I realize that changing up variables changes results. But if that is the only place to get the info, then it's the only info you have available. So if that's the only info you have, how are you applying it to your races? Understand it's different for everyone, but just gauging what multiple people's input is and figuring it out for myself from there.

In regards to testing outdoors, there just aren't a lot of places near me that I can ride for 20 minutes un-interrupted. Weekends are usually the only time I can get a long ride in, so a test is usually done on a weekday after maybe a rest day. In those cases, I can usually only get something done at 4 a.m. or after 8 (toddler and work). So they just typically happen on the trainer. It's by far the easiest place to just gut it out for 20 minutes.

In reply to some of the other responses as well, I realize FTP can only be part of the equation. Lately (last ~8 months) my outdoor rides have been with a group on my road bike. Switching back to the tri bike over the last few weeks, so I'll be going solo and getting better feel for consistent efforts, but it will still not compare to trainer rides. That will help dial it in. I guess the plan for the race at this time is to target a power for the first 30-45 minutes, then adjust based on RPE. But again, RPE for me just doesn't have a lot of experience to back it up at this distance. I'm looking to determine where I put that initial target. Don't want to be too far off and yo-yo too low and too high trying to find the right spot. 10 weeks left of training will help, but I'm still building, so it's not like I have the ability to go do 10 more 56 mile rides with a 5-8 mile run after to see how I feel. I figure I have a few chances, but reading other's experiences is a helpful guide sometimes. Just don't see many good clear expectations, and I guess it's for good reason.....haha. It's obviously not an exact transferable science between different individuals.

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Re: Trainer power and target race power [KG6] [ In reply to ]

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TennesseeJed

Aug 16, 17 8:24

Post #13 of 14 (1188 views)

I don't test outdoors either. Sure there may be a difference between indoor and outdoor FTP, but what will an outdoor test tell me? It will tell me the max power I can sustain for 20 min, or maybe 30 min, or maybe 60 min based on the test protocol, but whatever the number is, it does NOT tell me what power I can hold for 56 miles and still run a solid half afterwords.

Your trainer FTP is a great metric for setting your power targets for your interval sessions, and from what it sounds like you do those on the trainer. The differences between your indoor and outdoor power will evolve over time. After a winter of training indoors, I cannot hold my indoor power outside on the first few outdoor rides. After doing more and more outdoor rides, my outdoor power feels easier. The difference is a moving target, and in my opinion for the purposes of a 56 mile bike leg, not all that relevant. My recommendation to you is to set your "Race Power" at 80% of your indoor FTP and adjust from there during training. It may be 10% too high or too low depending on your endurance, but at a 200w FTP we are only talking 20 watt difference. Use your outdoor rides to fine tune your target and forget about indoor vs. outdoor power differences.

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