Watts indoors vs watts outdoors

Test inside and use different zones while doing work inside. I have two fans and use a big commerical fan when doing harder efforts inside.

I find I'm about 20 watts higher outside than inside most of the time. Zone 2 & 3 are eaiser to hit outside zones, but zone 4 and 5 are harder to do at outside watt zones.

I noticed this as well.  Others have mentioned there could be up to a 5% difference...depending on your trainer, the tire pressure, and how much cooling you have going on while on the trainer (fans).

For me...I think 5% is about right.

3/3/2011 - 20 minute all out test on the trainer.  Avg'd 262 watts.

3/6/2011 - 20k TT in 31:53.  Avg'd 269 watts.

Both the test and the race were done at pretty even efforts.  There wasn't a lot of variation in my avg power throughout.  I think during my 20 minute test, my avg power varied from 258-265.  And during my TT, my avg power varied from 267-273.

I also rode about 50 miles the day before the TT...and didn't ride at all the day before the 20 minute test...so you figure if anything, my numbers should have been significantly lower for the TT...especially because the effort was held over 50% longer.  And if anything...I was more exhausted after the 20 minute test than I was after the TT.  I wanted to quit after about 3 minutes into the test.  I really only got into hurt mode after 20 minutes of the TT.

And as with anything else...YMMV.

Yes to both of you.  Its closer to 10% difference though.

I my coach forgives me for the nasty gram I sent him a while ago but my word.....those numbers just don't work indoors.

There seems to be so much variability in people's responses to this question.  Some say they are exactly the same, others say 5-10% diff, ect.  I can't explain why, but I am significantly higher outside than indoors - like 30-40 watts.  Not sure why that is, but the numbers don't lie.  As Kathy suggests, I use 'indoor' zones and 'outdoor' zones.

Thanks all.  Its good to know that its common and that I'm falling in the range of variability.

I will talk with him about setting up 2 sets of zones.  Unsuccessfully trying to hold the zone yesterday destroyed the rest of my session.

I will also try adding another fan.

while i SEE a difference on occasion........ i find it hard to believe that the requirements to produce your digital readings are different from inside to outside.

if you are using the same powertap/crankbased  power meter inside and outside, it still requires a certain force/rpm to generate the numbers that show up on your screen.  it may be MENTALLY easier to generate those numbers outside through the use of momentum, coasting, cooling  etc.

the actual pushing on your pedals is the same inside and out.  it HAS to be or our systems for measuring the wattage's is screwed up and useless.

i agree there are variables that may prevent YOU from pushing on the pedals with the same force/speed, but the numbers 'should' be the same.

Of course.

The only faulty equipment here is sitting on the saddle.

I can chime in on this topic as soon as I start riding outside again - hopefully within a week or two. When I tested back in the fall (outside) my 20 minute power was 327 watts with a FTP/CP around 310. My last testing inside for 20 minutes was 336 watts and I averaged 342 watts over an indoor 10K last weekend. My power has definitely increased a bit over the winter.

I'm wondering if that number will jump up a bit once I get back outside.

God I hope not!  What age group are you in again Nate?

HA-HA! I'm in the 30-34 AG - check my logs to see what I'm planning on for races.

It looks like you'd probably spank me in the swim!

Being that we're in the same AG...you're allowed to qualify for Kona if you want...but you're not allowed to do any other racing in Hawaii...until I can get my motor installed in my bike that is. 

ETA:  I think I'll need a motor for my run as well...LOL

Regardless of whether or not my indoor vs. outdoor numbers vary (like I said, I believe they do), I know I'm working harder than I ever have on the bike so I know I'm getting better.  Having a number in front of you that forces you to work is the key (at least for me).

CJ

@nate,

can i ask what you are using for your PM?  those are some impressive numbers!

Tim

I'm using a PowerTap Elite+ laced into a DT Swiss 450 rim. I've only been using power since November of last year, and I already had a set of race wheels. Now my dilema is whether to just get a cover for the DT Swiss wheel or sell the wheel and get a Quark crank-based PM.