so most ftp test are conducted inside due to safety and ease?

"I'm not worried about it. A good workout is a good workout, regardless of the numbers."

Perceived effort isn't a good way to determine a good workout. If you do 2x20'@250 watts outside but inside are only able to do 2x20'@220, you aren't getting much of a workout inside even if it felt hard and there are pools of sweat under you when you finished. Put another way, you aren't going to get faster doing intervals in zone 1.

If I were you, I'd first make sure I took the suggestions to have adequate cooling, and then I'd begin with shorter intervals...maybe start with 1' and work on your ability to hold the higher wattage despite how it feels.

Actually, if I were you I'd ditch the trainer and just ride outside all winter.

This was a nice read. I think the first comment on this article has some merit. The fact that the flywheel of the trainer slows down much faster, means that you have to spend a little extra wattage on accelerating it. I can see this being 10-20 watts (just guessing).

It's not mental. That I am sure of. I just have to spin just 1 minute at the same power readings as outdoor riding to be able to tell that more exertion is required to maintain the same wattage.
I have a power tap G3. It recalibrates automatically, but I can check a manual calibration. My trainer is setup in the garage with the garage doors open and 2 fans blowing on me. I wonder if there is some loss of power with wheel based power meters on the trainer?

Good points, I should have said I was basing my comments on what I have found and the experiences of other cyclists who regularly train indoors and not on published studies.

This article covers it well.

http://alex-cycle.blogspot.co.uk/...harged-training.html

I have a Kurt Kinetic Road Machine. I have done all of my training outside for the past 14 months since I live in FL and weather is great for biking. So muscle adjustment might be a viable explanation. I'm not sure if that study agrees or disagrees with anything.

Haha. I wish 220W was my zone 1. I do 99% of my riding outdoors. It's something I noticed and was curious about. But I am planning on doing some work on the trainer in the winter months, mostly to save travel time to and from the trail.

Thank you. That is very clear and well written. I think it answered my question.

I find it a little easier indoors actually but I train indoors at least 60% of the time so I got used to it. When I'm on the trainer it's easy to maintain power and it requires less focus because the resistance is constant (no wind, elevation, traffic etc...) and once you settle into your right RPM range you're all set. Next step forward would be ERG mode on a Computrainer or similar and then it's all easy... just turn pedals over.
As far as comfort goes, use the biggest fan you can or two and a bunch of towels to wipe sweat off.

I've experienced the exact same thing as the OP. My FTP outdoors is 250, but indoors it is around 220-230 watts on the trainer (CycleOps SuperMagneto Pro). 250 watts on the trainer feels like 275-300 on the road. It's not just the effect of cooling - throughout the whole summer I mostly trained indoors because it's actually COOLER to ride inside with a fan blowing on me (77 degrees, air-conditioned) than it is to ride outdoors (60% humidity with temps in mid-90's, heat index 100+ - it feels ok when the wind is blowing but man, when you stop it is pure misery). If the power discrepancy was due to body temperature then I should be able to produce more power indoors. I live in Houston, TX by the way.

So the past two months I took a break from riding due to a knee issue. My first time back on the road was no problem and felt great. Then the next day I rode the trainer for the first time in two months and it was pretty brutal - it's like I had to learn how to "ride a trainer" all over again. It felt like I was riding through sand. There is definitely a huge difference between the inertia of a fluid/magnetic trainer compared to the road, and for me it takes a long time to get used to riding the trainer after a long layoff.

I just placed an order last night for a Lemond Revolution wind trainer (the super loud one with the most realistic road-feel of all of the trainers). I'm interested in seeing if there is a big difference in the power I can produce on the Lemond vs. my SuperMagneto Pro.

It does not. All it says that under specific conditions: "Crank angle and bilateral pedal force and angle data were collected from ten subjects instructed to pedal steadily (i.e., constant speed across cycles) and smoothly (i.e., constant speed within a cycle) against both inertias at a constant workload". This is not what is happening in real life.

I actually happen to have have exactly the same type of equipment that can simulate inertia forces and bike movements of real riding or just bring it down to the level of cheapo resistance trainer. The difference is quite significant. I tested it on few people but I have no time/resources/inclination to turn it into a real study.

Also if cooling is inadequate it will of course skew FTP as well.

The power you can sustain for about an hour is very good indicator of your FTP, but FTP is more of a conceptual value than a specific duration point on the mean maximal power curve.

Tests for estimating FTP as suggested by Andy Coggan lists among them the quasi steady state power sustained during 40km ITT as the most likely to be accurate. Whether such a TT takes an hour or not is pretty moot though as the mean maximal power duration curve is fairly flat around those durations. And that's the point - the maximal power sustainable in a quasi steady state for a long-ish time, it's not a specific duration.

 









Ok, well there are a couple more studies that suggest that inertial load has little effect on power output. Study 1, Study 2.

This study only suggests that inertia changes the chosen optimal cadence but says nothing on maximal sustainable power.

This study says that even though the muscle coordination/technique is different there is no change in efficiency between some trainer types.

This study suggests that PE on a trainer indoors is higher than outdoors at a given aerobic load.

To be clear, it is my thought that after some adaptation to the different technique required for an indoors trainer with low inertia the power differences between indoors and outdoors should be near identical. I'll be the first to say that true road feel is preferable... but a question is: Is it preferable because that is what we are fully adapted to OR because the inertia present in road conditions allows maximal output and efficiency. I think it is the former and not the latter.

So the powertap only re calibrates automatically if you are coasting. I am unsure how much distance/revolutions/time before the PT will auto zero. There is a chance that even if you stop pedaling on the trainer it isn't enough time for the PT to autocal.

Just speculation, it might be possible that your skewer and trainer clamping force might be causing some resistance in the PT hub (bearings or deflection of some part) that the PT hub isn't reporting. I can't think of how this would happen without it being obvious though.

Ok. I can sort of believe in this one. But then again human's muscles learn patterns very well and once the pattern changes they need to readjust if they can. Put it this way, when one has a race coming and that race happened to be long and steep climb they'd be way better of to prepare by riding in the mountains rather then on some flats.

Airflow and lack of stimuli make it seem harder. Which makes it actually harder. And thus better for your eventual outside rides.