Indoor vs. Outdoor TSS

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Location: North Carolina, USA

by JackRussellRacing

[flame suit /ON]

I always knew that indoor TSS "felt" much more painful to accumulate, but never had back-to-back data for comparison. Now I do!

I'm a total hack, but would be interested to hear if others have the same experience. Identical bike and powermeter (Quarq) is used in both scenarios. The 10-degree temperature drop outside may be the key differentiator, but I'm not entirely sure. So, check out how similar these are (below). At the end of the indoor session, I was noticeably tired/fatigued. It was not the hardest time ever on my rollers, but about what I expected (i.e. dripping sweat/legs burning). Literally 12 hours later, I rode outside on a similar effort but felt totally under-stressed and somewhat bored.

Indoors 71 TSS
Elite Real E-Motion B+ ERG rollers
70d ambient air temp, dehumidifier running, 20-inch fan pushing 1700 cfm
1:00:00 effort

Outdoors 84 TSS
Rolling city terrain
60d ambient air temp
1:00:00 effort


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by glepore

Because TSS is based on NP, and outdoors a higher NP is easier to achieve. Why? Look at the actual power files. For a given NP, outdoors you are likely doing short bursts greatly above your target NP with "recovery" periods well below. Indoors is pretty much steady state. For me, and I suspect for most, the outdoors scenario of over/under takes less of a toll on fatigue, even if the theoretical metabolic cost is higher.
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by benzebub

I too think this is the reason why indoor feels harder. There is a constant tension and pressure on your muscles.. no standing up or coasting in a corner, no traffic lights.. I do know that if I do an ftp effort on a local track outdoors that it hurts as much as indoor. ofcourse comfort is greatly increased because of airflow and temperature ("breathability" for a lack of better term, sweat not dripping of your body,...) outdoors.
But I could be wrong

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by GambadiLegno

First of all, indoors is always harder due to body temperature and lack of ventilation. What I do when training on rollers is riding on the lower zone that I would be riding if I where outdoors, and try to do cadence, force or fixed gear workouts.

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by prebsy

This is a common thing but you need to work on your indoor setup to help close the gap. When your indoor setup is dialed it will probably be easier to hit numbers inside vs outside.

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by topflightpro

It's pretty common for power numbers to be 10-15% lower on an indoor trainer than outdoors. Hunter Allen did a video about it:

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by Shrike

You need to multiply your outdoor time by between 1.3 to 1.8 to match the work done indoors (according to Trainer Road). Indoors is just that much harder.

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by nathanong87

prebsy wrote:This is a common thing but you need to work on your indoor setup to help close the gap. When your indoor setup is dialed it will probably be easier to hit numbers inside vs outside.


irks me when people say FTP changes inside or riding inside is "too hard"

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by Kurets

Agreed, with enough fans and reasonable temperatures I also find hitting intervals easier indoors. But, that only becomes the case after a few weeks of the indoor season. Outdoors I struggle with maintaining a constant effort, winds, corners, changes in gradient all work against it.

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