# Do you use two sets of numbers?

Discussion in 'Power Training' started by MarkM13, Jan 17, 2010.

1. ### MarkM13 New Member

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Greetings.

I'm new to training with power. I got my PT about a month ago just as New England went into a deep freeze. As such, until yesterday I had only used it on my trainer. During my testing for FTP, CP and the CTS field test I was pretty disapointed with my numbers. I took it as a sign to get to work, and have been digging in. Yesterday however, was my first day riding with the PT outside. The difference in numbers was substantial.
For example, indoors it is a huge effort to stay above 300w for a two min interval. Outside however, I was doing 10' climbs at 400+w. I've been doing a lot of reading here as to why there is a difference. After reading Alex's comprehensive blog on the subject I can't help but wonder if it be easier just to repeat the testing outdoors and have a second set of numbers. If you're stressing the same part of the aerobic system with two different sets of numbers, I can't see that it would matter. I figure I could just create another profile in "Power Agent" to reflect the different numbers.
As I said I'm new to all of this; so I'm wondering if other folks use two sets of numbers to allow for large differences.

M

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2. ### gman0482 New Member

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I'm not sure that I'll be of much help, but I know that the output you get on the trainer, equals to a higher one outdoors. I haven't done any testing outside yet, as I'm also in New England and inside for now. The time you spend on the trainer is also ~20% greater than outside, so 2 hours indoors, is like 2.5 hours out.

I would definitely go by the numbers outside IMO.

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3. ### rbarker76 New Member

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You averaged over 400 watts for a ten min climb outdoors but can only average 300 watts for two min on the trainer?
Again, we are talking about average power for the interval, right?

If so, that is such a differance that something must be wrong. You mentioned
It was the first time outside with the PT and the temp is around freezing, did
You zero the torque before the ride?

I make around 3 to 5 percent lower power for the same time interval
Indoors versus out. You are talking about 25 percent lower for 8 less minutes.
Something does not jive.

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4. ### Fightin Boba New Member

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For purposes of establishing target ranges for workouts, I would recommend having two sets of numbers for now. I would also recommend following the advice in Alex's blog on optimizing your indoor power. Perhaps as your indoor power improves, the gap between indoor and outdoor power will decrease, negating the need for two sets of numbers. Also, once you have done some representative workouts in each environment, those workouts will serve you better for setting subsequent targets (IOW, "alls you can do is alls you can do").

I would also recommend that you reset the zero offset on your powermeter each time you ride. The temperature swings from indoors to outdoors in your area can invalidate the resultant power numbers that you see.

Finally, if you are using WKO Performance Manager, and you are riding indoors predominantly (perhaps 75% of your weekly TSS), I would recommend using the FTP number from indoors in order to keep your PMC relatively accurate. On the other hand, if you are able to mix in more outdoor TSS like me (in California), where perhaps 75% of my weekly TSS comes outdoors, then go with the outdoor FTP test as the basis for your PMC. There are certainly other ways of managing your PMC, but this is the most simple if you TSS comes from predominantly one environment over the other.

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5. ### doctorSpoc New Member

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are you using as powerful a fan as you can find?

1) cooling is the biggest (by far) contributor to lower numbers indoors.. think about the enormous cooling affect of a 40km/hr wind going over your body outdoors compared to a puny little fan (if you are even using one) pushing a miniscule amount of air inside.. ride in an unheated room with powerful fan.. i'm in canada and i ride in an unheated room with the window open in the dead of winter (down to -30C).. i just wear a long sleeve shirt and remove it as i get warmed up..

2) a second largest contributor to lower numbers indoors is lack on inertia.. not sure anyone completely understands why this is but maybe it's just something your legs gets used to outdoors and is just weird for it indoors but if you increase it riding indoors will feel more natural.. again think about your body weight + bike weight outdoors, compared to indoors where the intertia is contributed by your lightweight rear wheel and maybe a tiny fly wheel if your trainer even has one..

also those lower numbers do really mean you are doing less.. you are really adapting less.. it's the power that you are pushing that stimulates the adaptation.. just because you are hurting the same or even more doesn't mean you are doing the same or more...

i also used to have lower number indoors but getting the cooling under control + getting inertia up as well and now my everyday indoor numbers are actually higher than my outdoor numbers.. all my personal all time records are still outdoors.

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6. ### lanierb New Member

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That difference is just too big I think. One of the two could be off a bit. I would definitely recommend zeroing the PT a couple times at the start and during your ride -- temperature changes can cause it to start reading wrong.

However, even after you do this I'm betting you will still see a big difference. It sounds like you put out way more power on hills than on the flat. I'm the same. At times it's been as much as 10% (measured FTP), mostly having to do with standing on the pedals, which seems to drastically raise my FTP.

What to do? Well it's pretty hard to maintain two FTP numbers (it's hard enough to maintain one), so I just pretty much use whatever seems to be right for the kind of riding I'm currently doing. If I'm doing a lot of long hills, I end up using something that is somewhat between the two numbers. If I'm doing mainly flats, I use the lower number. I almost never use the upper number since it's only relevant on a constant hill, which isn't accurate for almost anything except a hill climb.

Bottom line: pick the FTP that closest matches the terrain on your average ride. It's not perfect but that's okay.

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7. ### doctorSpoc New Member

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yeah, i think the number difference is a little too different as well.. MarkM13 - are you zeroing before your rides?

to the OP... set the PT to auto zero and before you start your training sessions.. just lift your rear wheel.. spin the crank up a few times, stop let the wheel continue to spin and wait for the power to read zero.. then you are good to go.. shouldn't really have to do it between intervals but if things look funny you may want to as well...

and yes, he is power on hills will also tend to be higher than on flats..

so if you put all those things together.. improper cooling and low inertia, improperly zeroed PT, hill vs flat (indoors) and that might add up to a big difference indoors and outdoors..

i think the real bottom line is that you really don't need FTP to know how hard to ride an interval.. you seem to already have a really good idea of what power you are able to ride for certain intervals of time.. this is what should dictate your power for the interval and not some artificial, approximation of what some idealize average user might be able to do.. FTP and power zone are a VERY loose approximation of what someone might do and is good for the newbie.. everyone is different though (has slightly different power profile) and if you know what you can do for interval x that is a much better guide for what you should be doing i.e. it's customize for your power profile.. people get caught up in the numbers and think there is something magical about FTP and power zone but there really isn't.. and if you are tracking your ave power for e.g. 20 min intervals (the second best method of approx. FTP.. must have seen the 6th deadly sin in Alex's blog) you can track progress as well without even doing formal testing at all..

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8. ### Animator New Member

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To my surprise, this same inversion has happened to me this winter. I used to hate riding indoors. The biggest change I made was to move the fan, a large box fan, behind me. My mouth doesn't dry out and it feels like a tailwind, which generally inspires me to ride harder. I also don't turn on the TV, but rather I wear headphones and listen to excellent music. Now I can't hold the same power outside in the cold as inside, which is a weird experience. Hopefully when it finally warms up, my outdoor power will equal or surpass my indoor power! (and yes, I'm careful to zero torque)

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9. ### gman0482 New Member

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I was told by my LBS owner, who's an ironman triathlete, that normally whatever your AP is on the trainer, it should be somewhat higher out on the road. Now, we were talking about KK trainers during that conversation, but my guess is it should be similar in all. Having said that, I doubt that the difference could be anywhere near 100W. Maybe 5~20W, IMO is reasonable on a flat average. Then again, I haven't compared my own yet either.

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10. ### swampy1970 Well-Known Member

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I have two sets of numbers - indoor and outdoor. I'm not sure what the dealio is but the effort (and wattage) on the trainer is closer to what I get on the climbs - which is less than what I get on the flat outdoors. I know it's supposed to be the other way around but... yeah.

I thought it might be a positional thing - so I rode up the hills on the drops and low on the brake hoods - I sucked even more. LOL I'd kill to be able to hold the power than I get on the flats for an hour plus whilst going up hill for 30 minutes.

Given that my first race in 15 years is ~9 months away, I reckon I have enough time to give birth to a position that's a little better.

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11. ### frenchyge New Member

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I use 1 number and just understand that the trainer is going to feel slightly tougher than the road.

It's the P-cranks that've ruined your stroke. Going uphill is where you really have a lot of resistance against which to bang that big downstroke without the pedal moving out of the way. Didn't you know that all the best roadies have an accentuated downstroke? See if Frank will still give you your money back, and good luck in your triathlons.

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12. ### DancenMacabre New Member

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One number.

Because for everything > 3 min (L5 and below), I make the same power indoors as outdoors. It has taken practice, a good setup, and maybe a more than average disdain for cold/wet/windy weather & a deep appreciation of super efficient use of training time.

The short, short stuff ( < 3 min below) is not doable for me since i can't stand & pedal quite the same way. Everything else.......1 number

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13. ### swampy1970 Well-Known Member

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... I think it's the added resistance of the naff bearings in the powertap that seemingly adjust at will. The added weight of the "it only looks like carbon" spacer on the steering column doesnt help.

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14. ### doctorSpoc New Member

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to me you really do want to use one number.. the outside number.. because that is where you are preparing to perform and that should be the reference. because in terms of CTL, TSS etc if you can't put out your outside numbers inside, you really are doing less and you want the performance manager to reflect this.

but when all is said and done it's not going to make a whole lot of difference in your training because if you can only do 300W for 20mins, you can only do 300W for 20mins... so higher or lower FTP is not going to change that.. all you can do, is all you can do..

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15. ### MarkM13 New Member

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Hi All,

Thank you for all of the most useful comments. This is a great forum.
In going back through the files I realized I made a lot of rookie mistakes.
(Hey I did say I'm new to this). W/o going through every detail I'll just sum it
up by saying that now the peak power differences at 5min were 54w. Not as large
as i first thought but still substantial.
At least now I realize that I have to:

- Make sure torque is zeroed at the start of the ride.
- Do something about my ventilation. There's always a large puddle under me.
- Try out a quality trainer (mine's an old school mag trainer from 1993).

FWIW I did have two coaches confirm that some folks do use two sets of numbers.
However after addressing the above, I'm hoping the gap will be even less.

Thanks again,
M

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