Power and Inside versus Outside

Pat Koss

From the OS Best Practices document in the wiki:

"In general outdoor watts are roughly 10% higher than indoor watts so you can adjust your expectations accordingly."

Why?

I just installed my Quarq last week so power data is new to me.  So far I've been inside on the trainer, but thought about going outside tomorrow for the VO2 work.

Just curious.  Learning.  Thanks in advance!

Al Truscott

"In general" is the key phrase. Everyone's unique. I have about the same FTP inside and out.

Why the difference for many folks? Maybe related to any of the following? This is all speculation on my part, I'd love to hear if there is a real reason for this common observation, that also allows for the exceptions to the rule, like me.

• More easily bored inside than out, so less able to push to the max
• Insuffficiently cooled inside; e.g., I find that if the ambient temp is over about 50f, I need a good fan to reach my potential inside.
• Changing terrain outside, even on the flattest road, requires the brain to ramp up and be ready for contingencies; any uphill is also an opportunity to get a higher output for the same perceived RPE for reasons discussed elsewhere in the forums.
• Public vs private efforts differ. We can almost always run faster in a race or when training with others than all alone. Same applies to cycling, even the cars around us trigger the sense we're being observed, and so we subtly ramp up the effort without even knowing it.

I'm assuming, of course, that the bike, rider position on the bike, the power measuring device are all the same indoors and out.

rmiller

Everything Al said - but I'd include one additional factor: Indoors you are on a trainer, which provides constant resistance. Outdoors, even on a 'flat' course, there are slight variances in terrain, and you get the opportunity to rest or back off slightly. IMO, this is expressed by the fact that indoors on a trainer, nominal power and average power are rarely off by more than a couple watts, if that - meaning your VI is pretty damn near 1.0. Outdoors, even on flat ground, a VI of 1.03 or 1.04 is pretty darn good. So even when you think you are pushing all the time outdoors, your effort does vary. Granted, these moments may be fractions of a second during a legit outdoor FTP test - but over the course of 20 minutes, it can add up.

William Jenks

Mine are higher inside than outside. Maybe because I have nothing else to focus on besides the number....just to show there is a counterexample out there. Clearly enough cooling and psychology are both important.

cgres123

1 other thing to take into consideration, if you are on a trainer inside during the out season on a road bike and then you transition outside and train on a tri bike your watts will change too. Like Al said we are all unique I have found for myself it's not so much 10 percent has 10 watts.

kens1964

Alright, so maybe I should start a separate thread for this topic, but here goes: I have one of those flat panel tv's in my work out room that has an internet connected feature so I can watch Netflix, Amazon Instant Video, look at FB (why?), etc. But here's what's fun and motivating. It has a YouTube feature and I can search the most rockin' band I can think of and it will play one video after another. I turn up the volume and turn off the lights, and bang! About as much motivation as I can get from training indoors. Maybe better than watching all the Ironman Hawaii DVD's I have. So, last night it was The Black Keys. Before that Santana, Led Zeppelin, Black Crowes, Lenny Kravitz, Red Hot Chili Peppers, Bruce Springsteen, Def Leppard, AC DC--whatever it takes to get me pumped up for those FTP and VO2 max intervals. Tried the lights off on the treadmill, too, and it worked pretty well, but almost lost my balance last night (oops). So, that's how I keep the power/effort up on the indoor trainer. What motivates you?

cgres123

@ Ken , you should start a new thread. This one is about a different issue so folks will reply to Pats subject line. Others that would have a suggestion for you will not even know you posted that here, make sense?

kens1964

@ David - Sure thing. But I was responding to Al's point that motivation is different inside than outside. True, a trainer (or treadmill) can be very boring. Time passes a lot slower, so effort may go down for psychological reasons, and therefore indoor FTP might be lower than outdoor FTP. I will start a new thread. : )

Joe Matchette

For the past two years, my tested power inside has been the exact same outside. The only differences are that I am out on the road and I don't have music. Other than that, the bike, fit, etc are all the same.

I keep hoping that I will get the '10% bump' I hear about.

John Withrow

I have my own "theory" of why most people have higher outside FTP than inside. My own personal FTP is about the same indoors and out, but maybe slightly higher indoors.

Disclaimer: RnP and a couple of other smart peeps have already said my theory is crap, but I'll re-tell it here anyways because I still believe it.

I think most people have a lower FTP inside because their bike is fixed onto a trainer and they would normally get a little bit of extra power from the slight rocking of the bike outdoors and those tiny leans give you a slightly better push onto the pedals. I know when I'm really pushing it when I'm on a fixed trainer that I can hear my carbon fiber frame creaking and almost screaming... When I'm on a fluid trainer I can't put out nearly the same power as I can outside.

Now back to my n=1... I now do 100% of my indoor training on my e-motion rollers. This is a much more natural feel like on the actual road. So when on my rollers it feels like the road and I can rock back and forth and swerve a bit ever so slightly as I ride, but I don't have any of the distractions of outside like cars, slight grade changes, wind, etc... I can just pedal and not worry about anything except pushing watts. Therefore, my inside FTP is very similar to my outdoor, if anything the indoor being slightly higher.

Pat Koss

Thanks all. Seems there are a number of points-of-view out there from rocking to AC DC (yep, that was a freebie).

I'm going to head out tomorrow after it warms up and try the VO2's on a flat straight stretch. First time out with the new Quarq. Let's see...