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FTP Indoors and Out

xine2kgts

Apr 7, 12 16:15

Post #1 of 14 (1458 views)

FTP Indoors and Out	Quote \| Reply

I tested my FTP last week and it was 232 indoors. This week I tested and it was 271 outdoors. When I am doing intervals on my trainer indoors should I follow the my indoor or outdoor FTP numbers?

GMAN19030

Apr 7, 12 16:41

Post #2 of 14 (1424 views)

Re: FTP Indoors and Out [xine2kgts] [In reply to]	Quote \| Reply

Most of us see a delta between indoor and outdoor FTP. Usually not as large a % as you but 5-10% is common.

I would use the indoor # to pace indoor intervals. It would be hard to hit your indoor intervals with outdoor numbers given the 20% difference. Apples to apples.

NickG

Apr 7, 12 17:12

Post #3 of 14 (1404 views)

Re: FTP Indoors and Out [xine2kgts] [In reply to]	Quote \| Reply

xine2kgts wrote:

I tested my FTP last week and it was 232 indoors. This week I tested and it was 271 outdoors. When I am doing intervals on my trainer indoors should I follow the my indoor or outdoor FTP numbers?

That is nearly a 40watt difference, kinda high. Makes me think you either held way back on the indoor sessions and need to man the fuck up or you did your outdoor test on a hilly course that allowed you to spike your watts. What was your avg. vs. np for the outdoor ride?
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devashish_paul

Apr 7, 12 17:57

Post #4 of 14 (1375 views)

Re: FTP Indoors and Out [GMAN19030] [In reply to]	Quote \| Reply

I tend to see around 5% max. Make sure your indoor setup has a good fan. It could be a concentration thing too. I find that my indoor 40 min TT power number is pretty well bang on what I can do outdoors for an hour. I'm more and more convinced (for me) that although it could to with inertia, the biggest item is concentration.

Are you using the same measuring device....ex: if you use CT indoors, it measures power at the hub (after you do the rolldown test). If you are using another bike with SRM or Quarq outdoors, it measures at the crank and should read a touch higher as it measures prior to drivetrain losses.

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nickwhite

Apr 7, 12 19:35

Post #5 of 14 (1323 views)

Re: FTP Indoors and Out [xine2kgts] [In reply to]	Quote \| Reply

xine2kgts wrote:

I tested my FTP last week and it was 232 indoors. This week I tested and it was 271 outdoors. When I am doing intervals on my trainer indoors should I follow the my indoor or outdoor FTP numbers?

Like Dev said above, make sure you have a GOOD fan. Like, your eyeballs should be dried out good. If you do, your FTP should be close... If you use a Fluid trainer, I'd expect around 10-15 watts difference. Computrainer, 0 watts difference.

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JollyRogers

Apr 8, 12 3:24

Post #6 of 14 (1247 views)

Re: FTP Indoors and Out [xine2kgts] [In reply to]	Quote \| Reply

I see equivalent numbers indoors versus out on my road bike - with a 7200 cfm fan blowing on me.

I have a delta indoors versus out on my TT bike - don't know why, probably mental.

I use outdoor numbers since that's where I race.

All you can do is all you can do.

camaleon

Apr 8, 12 4:01

Post #7 of 14 (1227 views)

Re: FTP Indoors and Out [xine2kgts] [In reply to]	Quote \| Reply

key word "GOOD" fan

I also see a +5-10%
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mcmetal

Apr 8, 12 15:47

Post #8 of 14 (1133 views)

Re: FTP Indoors and Out [camaleon] [In reply to]	Quote \| Reply

It's funny how often this topic keeps comming up. There must be at least 100 threads on this.

There are many reasons for the difference in the wattage. When cooling is the culprit it is pretty obvious. I use a 6800CFM fan and it keeps me nice and cool and I still see a difference.

As far as the real reasons:

1 - When pedaling outdoors the bike moves and you move and this has an impact on muscle recruitment and micro breaks.
2 - When on a trainer you have to overcome the resistance over the entire pedal stroke. In one of the other threads, someone posted some pics showing the different muscles recruited at different parts of the pedal stroke. Outdoors you tend to get micro breaks.
3 - When outdoors you have more kinetic energy. If you stop pedaling on a trainer it will generally stop in a few seconds. The lack of kinetic energy creates increased metabolic demands.

The best thing to do is is track your indoor wattage separately from outdoors. What I find happens at the begining of trainer season is that I need to get myself in trainer shape. When you first start the seaons you might be say 10% lower than your outdoor wattage but after the first couple of weeks or so it will get closer.

One other interesting thing that I notice is that RPE on the trainer is higher than outdoors at ANY wattage. What I mean is even in Z2 or low Z3 on the trainer I will feel some RPE, call it 1. When outdoors in those zones my RPE is 0.

I tend to think its a combination of all 3 and that you are getting some micro breaks outdoors that you just don't get indoors. Some people physiologically handle riding without micro breaks better than others.

bartturner

Apr 11, 12 6:29

Post #9 of 14 (1014 views)

Re: FTP Indoors and Out [xine2kgts] [In reply to]	Quote \| Reply

This comes up all the time. There are two camps.

1) Indoor and outdoor should not be different. Make indoor more like outdoor. Which usually is 1st cooling. Get more cooling. 2nd have a bigger flywheel. The 3rd factor is motivation. I am convinced I am as motivated if not more indoors versus outdoors.

2) Training by indoor FTP and outdoor FTP independently from one another.

I worked on this a bit this off season and it is not possible to get my indoor FTP in sync with my outdoor. So I train to indoor and outdoor FTP independently. There are people on the forum that will insist this is wrong, etc. But it is what it is atleast for me and I am satisfied I did what I could and it just is not possible.

BTW, I have seen my indoor training increase my outdoor FTP.

(This post was edited by bartturner on Apr 11, 12 6:30)

orphious

Apr 11, 12 6:51

Post #10 of 14 (991 views)

Re: FTP Indoors and Out [bartturner] [In reply to]	Quote \| Reply

Is there a way to estimate your FTP with out a power meter? I use CT for indoor rides but for outdoor I just use the Garmin Speed and cadence sensor and record with the 310xt. Just wondering if you can get a rough estimation from that data.

(This post was edited by orphious on Apr 11, 12 6:52)

Jon h

Apr 11, 12 7:04

Post #11 of 14 (972 views)

Re: FTP Indoors and Out [xine2kgts] [In reply to]	Quote \| Reply

I am usually 5-10% lower inside on my fluid trainer. That seems typical of many others as well.

torrey

Apr 11, 12 7:24

Post #12 of 14 (956 views)

Re: FTP Indoors and Out [orphious] [In reply to]	Quote \| Reply

No. You can get a rough estimate of your indoor power on a trainer without a power meter, but there is no easy way of estimating outdoor power.

bartturner

Apr 11, 12 9:23

Post #13 of 14 (907 views)

Re: FTP Indoors and Out [Jon h] [In reply to]	Quote \| Reply

I am in the 5-10% range difference. But I am also done indoors for the rest of the year so I am not exactly sure what my difference would be right now. I do not know of an accurate way to estimate power without a power meter.

M.E.T.

Apr 11, 12 9:27

Post #14 of 14 (904 views)

Re: FTP Indoors and Out [bartturner] [In reply to]	Quote \| Reply

...Since energy system utilization and adaptations happen across a continuum this will surprise no one on this board.