In short... yep.

In long... it can depend on the trainer, cooling, motivation, gearing, position on the bike, hydration, *insert everything else here*. The biggest one I find is the the 'feel' of the trainer, so the flywheel and inertia/momentum. If the trainer is sluggish and the pedalling feels laboured all the way around then that's not like riding outside at all - it's good training, sure, but you'll likely fatigue earlier and produce lower watts indoors. I still have a special place in my heart for the Lemond Revolution for TT efforts indoors. That thing is so buttery smooth and the massive flywheel really kicks the pedals over... like a nice flat TT outside.

Just my 2c from experience.

I'm hoping a qualified coach can chip in with more details and perspective on this here on ST.

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Shane Miller - GPLama
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a lot of people "exclude zeros" in their power measurement. on the trainer there is virtually zero coasting, outside there is a lot. Just one possible reason. Also personally, I can go harder outside, its easier for me to push hard to a location (top of a hill), rather than an arbitrary amount of time (5 minute interval).

Trainer watts will be lower; yet, steadyly increase what you can do indoors.

Outdoor watts with small elevation changes will be better with significant increases in watts as you increase the feet climbed during a ride.

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Indoor Triathlete - I thought I was right, until I realized I was wrong.

For me, when I was in shape, I was usually stronger on the trainer when compared to training rides. But on race day, ~15 watts higher outside. But only for TTs when I could push to exhaustion.

I ride a lot indoors, so I wanted to see what my numbers look like

Looking back over 6 years of riding data, using the same PM...

5sec / 1min power - every top 20 power interval is from outside. I can’t throw my bike indoors like i can outdoors and I think that’s part of the reason i can’t hit top end numbers inside.

5min / 10 min power - my best at each of these metrics is outdoor, but 15ish of the next 20 are indoor. My top for each is <5w higher outdoor than indoors. So I’m calling this one better indoor vs outdoor, but close

20min / 60min / 90 min power - almost all the best are indoors. It’s hard for me to get an open set of roads for these durations outside

So for me? Indoor let’s me focus on legs w/o thinking about the elements around me. But outdoors I can stand up and always get a little extra “oomph” that i just can’t on zwift.

Other than for simply an ego boost, I will never understand why people would exclude zero's indoors or out. But its also never made sense to me why people spend money on a PM and don't use it. I guess the bling factor goes hand in hand with the ego stroking.

Not a, but the only reason I could see for the discrepancy between inside and outside, on the same bike with the same PM, would be cooling. A big ass fan is essential for indoor training! Otherwise its just motivation and desire to suffer.

Just my $.02

20 would be pushing it. But I normally get 5-10 percent more outside compared to the Computrainer.

For a lot of people there can definitely see an increase. 10%-20% would seem like a lot but you’ll find out I guess. I don’t find much of an increase, if any outside, but I’m not often doing the same working indoors vs outdoors so it’s a bit hard to tell.

Something like 95% of folks have less power indoors vs outdoors (source: I don't recall).

I remember sharing my frustrations with an Olympic triathlete, and she said the same - delta indoor vs outdoor power is real.

My guesstimate is that there is a 10% difference if indoor vs outdoor in "normal* conditions. If you add high speed fans + lots of Zwift, the difference can decrease to 5%.

Having said that, it is personal. A friend of mine hits better indoor vs outdoor number.

Just this morning I read (what I thought was) a good article on treadmill vs outdoor running - difference in psychological and physiological markers. I think the situation is even more acute on the trainer. https://www.runnersworld.com/...round-running-study/

What I do - I recalibrate my indoor training wattage to make it more or less equal to outdoor... And try not to stress out that my (indoor) numbers are too low.

Hope this helps

I always put out more watts indoor vs outdoor.

This blog item I wrote 10 years ago hasn't aged too badly:

https://wattmatters.blog/...harged-training.html

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http://www.cyclecoach.com
http://www.aerocoach.com.au

I used to find it hard to work as hard indoors as out. That was when I didn't have proper cooling and found indoor training more tedious than I do now.
Since setting myself up better with decent cooling and using Zwift, I manage very similar figures either way for similar durations. However, in general, my indoor sessions are shorter at 45-90mins and therefore the intensity is higher. So I can achieve similar performance indoor and out but actual average power levels for sessions are higher indoors because they are shorter, more intense sessions. My highest ever 20min power was an indoor FTP test. Had I done a 10 mile TT during that period, my highest ever 20min power might well have been outdoors instead.

Thats my experience so far as well. Kind of annoying to be honest. Did 3x30 at x - x+10 - x+20 indoors with 5min easy in between. Cant hold x outside for 15min. Blah

This is pretty close to where I'm at, Short bursts (everything 5min and under is outside). Then starting at 10 min and over is inside. I think that a lot of that has to do with me not being able to find that dark place in my mind outside because I'm trying to keep my other senses alert. I have never done a closed stand alone TT or any type of bike race. So, there is no way to know if I could go that deep if I could just focus on moving the pedals.

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https://www.strava.com/athletes/23685202

I'm almost always 8-10% higher outdoors, and don't think I'll ever match it. Outdoors you can leverage the bike better using more muscles, take advantage of the terrain, and even on a hot day moving is natural cooling.

I could see how someone with good cooling that doesn't wildly swing their arms and rides with a consistent power get close, but I just find there are too many advantages outdoors.

 
x2 on this - i sold my smart trainer last year and back on the old lemond which is so smooth. Noisy as h*ll, but the best trainer to ride for feel for sure.


In short... yep.

In long... it can depend on the trainer, cooling, motivation, gearing, position on the bike, hydration, *insert everything else here*. The biggest one I find is the the 'feel' of the trainer, so the flywheel and inertia/momentum. If the trainer is sluggish and the pedalling feels laboured all the way around then that's not like riding outside at all - it's good training, sure, but you'll likely fatigue earlier and produce lower watts indoors. I still have a special place in my heart for the Lemond Revolution for TT efforts indoors. That thing is so buttery smooth and the massive flywheel really kicks the pedals over... like a nice flat TT outside.

Just my 2c from experience.

I'm hoping a qualified coach can chip in with more details and perspective on this here on ST.

My personal results are that my indoor FTP tests are always higher.

I can close my eyes and scream uncontrollably in the last 3 minutes with no worry of bike handling.

Overheating inside is not an issue for me because of the size of my fan and blower.

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"If it costs you 30 minutes at Maryland so what" -dwreal