Indoor vs outdoor TSS vs IF

I’ve tried looking through support and forums, but have not found a clear answer. With endurance rides, going from indoor to outdoor workouts, the TSS stays the same, but the IF obviously goes down, but then that doesn’t match up with the recommended power ranges. For example, Brasstown indoors is 1.5 hours with TSS at 70 and IF 0.68, but if you do the same workout outdoors, the time increases to 2.25 hours, but the TSS is 70. No IF is listed for the outdoor version, but the recommendation is to stay in the 65-75% range (just like indoors), but the calculated IF for a 2.25 hour ride with TSS of 70 is 0.56. If you do a 2.25 hour ride at IF of 0.68, then TSS becomes 104. What I’m asking is if the TSS and IF (recommended power ranges in notes) are more important than time? In other words, if I can keep IF and TSS close to indoor workout, don’t worry about time when outdoors?

TR assumes that you’ll be less efficient outdoors during endurance rides with stoplights, traffic, etc. so they build in some extra time. I would just stick to the target power zone and then ride for as long as it takes to get the TSS. If you live in an area that’s conducive to constant pedaling then your time will probably be closer to the indoor ride than the outdoor.


Yes. I’ve got a bunch of examples where a 90-minute ride has almost no downtime. In addition due to the roads I need to occupy a full lane while riding out of the neighborhood, and that usually means a high-power burst to get up to 20-30mph. And that ends up increasing IF and TSS versus the planned workout.

Using your Brasstown example:

I’d do a 5 minute warmup at roughly 50% and then just target 70% FTP for 80 minutes and then 5 minute cool down.

Example from a couple weeks ago (with Endurance zone highlighted):

only 3+ minutes of coasting, and the intervals were basically Brasstown:

  • 5 minute warmup
  • 80 minutes at 70%
  • 5 minute cooldown
  • 17 ‘bonus’ low-aerobic minutes getting back into town due to the route

When feeling good I’ll continue riding at 70% until I’m 5 minutes from home. That day I didn’t sleep well, stomach upset, had a stressful day at work, and so I just did the 80 minutes and did the bonus minutes at recovery zone.

Yeesh! 368ft elevation over that distance. You officially live on a pancake! :rofl:

I’ll be following your advice as I try to push more of my workouts outdoors this year. :+1:

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My Garmin only gave me 177 ft elevation :joy: Does crossing an overpass twice count as climbing? One of the few places in the world where the toughest ‘climb’ is a 40 minute descent from 60’ to -5’ into a wicked headwind :rofl: Seriously that wind has humbled many a climber that decides to try our Wed night worlds.

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I’m pretty sure my street is over 10%. You’re either going up, or down, a fair bit.

It’s funny how a headwind grinds you down. Nothing quite like it really.
Erg mode outdoors!

I’ve done a few longer rides outdoors recently. Just loosely following the power recommendations and trying to nail the tss so that I don’t overdo it. Keep finding myself miles from home as I reach the allotted tss so at that point I just back it down to z1 and make sure I’m eating lots.