“not all TSS is created equal” : Why we all keep talking about it?


So I have understood that “not all TSS is created equal” : Why we all keep talking about it?
Can I also disconsider CTL and related metrics?
Why not talk only about volume in hours instead?
I find hard to believe PMC charts are useless.

Thank you,

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You should only talk about it in context.

A track rider is going to have much less TSS/CTL than a stage race rider.

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  • Because it’s the “best” single metric we have that intends to capture the greater complexity that hides in training and evaluating it.
  • It’s not perfect and needs to be considered in a wider context. But it is not worthless since it’s not perfect.
  • There is still value in it, but you need to realize it is not the only aspect to consider.
  • Volume alone ignores intensity.
  • Not sure if exactly what “volume” you’d measure?
    • Time is flawed… 1 hour “easy” vs 1 hour “hard” are NOT the same.
    • Distance is not great either for the same reason.
  • This is one aspect that TSS aims to solve.
  • Not sure anybody said they are useless?
  • But like any metric or combination, it should be taken in the broader scope of training and actual rider feelings.
  • Nothing single metric or method is all inclusive. You need to take it all in and look for the forest, not just the trees.

It’s not super-scientific, but I like to track CTL * FTP (W/kg) as a measure of my real fitness. I also like to track CTL/ weekly hours to get an idea of weekly “intensity”


Some additional info:


First of all tks.

The volume I had in mind is time + training plans ( specifics workouts) + regular tests to adjust the zones.

My frustration on being attached to those number is that you can fell but you can’t really see what’s is going to happen (at the end) following a given plan.

Get any training plan and put it in a PMC chart and unless you keep rising your weekly TSS you won’t see that beautiful CTL going up… but we all know that you are improving by following a plan.

So, again, why worry about CTL, TSS, IF ? we all know we should work all zones and like TSS not all IF are created equal.

Is it tech talk only?

What am I missing here?



By reading these articles I see one good use for TSS: to allow you correctly dimension specialty workouts factoring the impact they cause. Otherwise we would just tend to rise weekly TSS without that consideration like in the text “A workout with 2x 20 minute intervals can result in the same TSS as a workout with a single 40 minute effort, but anyone who’s ever ridden at sweet spot knows it gets dramatically harder as efforts get longer. In this case, the TSS calculation of time and intensity doesn’t tell the entire picture, as it ignores the context within which that time and intensity is generated.”

But by doing that the rest of PMC (CTL, ATL, TSB) becomes blurred, no?


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  • No, it is info. And depending on your needs and ability to digest that info in perspective of other aspects, you can leverage it to help direct your training.
  • Not really sure. It seems like you are spinning from all the possible info.

  • If you are new to training, I’d suggest largely to ignore all that data. Until you get some real training into your cycling life, establish a bit of history, and see how you actually respond to structured training, there’s not much point in digging too deep into the weeds.

  • That is best left to people with a couple of seasons under their belt, the ability to review the data closely with respect to they actual response they had, and then possibly adjust their future training in light of that.

  • Prior to that, sweating details like you mention are largely academic without the ability to really frame them.


Not really, I dont think I’d use the word ‘dramatically’ it is just sweet spot (just annoyingly uncomfortable). Of course in regards to your comment it might be true if really pushing the sst duration to extreme lengths, which I don’t think is standard in any TR plan. Threshold now that is a different matter.


All these metrics are useful once you understand how they relate to you and your performance. Like others have said you just need to consider the context.


Don’t throw the baby out with the bathwater.

Is TSS a perfect metric? No. Is it part of one of the better frameworks we have for quantifying and analyzing workout stress, training load, etc.? Yes.

The introduction of consumer grade power meters and Coggan (and others) creation and popularization of concepts of Normalized Power, Intensity Factor, Training Stress Score (some of which are based on other models) and other metrics built on top of that was a huge change in our ability to quantify and analyze cycling training. (CTL/ATL are based on a pre-existing impulse-response model that was used in other athletic training and applied to cycling as part of this framework.). Prior to this model people would use time, HR, speed, distance and other metrics to quantify their training, all of which have bigger problems than this power-based model.

If you have not read it, I would highly recommend Coggan and Hunter Allen’s book ‘Training and Racing with a Power Meter.’ And if you want to geek out, there used to be a lot of discussion on the wattage google group. You can also check out goldencheetah.org and references from there. GC a different framework, though I have found it largely to match trends with other tools that use Coggan metrics.

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Maybe if you’re a sprinter, but the enduro guys/gals I know rack up a LOT of TSS points.

ETA: Here is a slide from Coggan’s presentation on use of power data for track cycling {Track applications for a powermeter | PPT}. It’s only for one rider, but CTL was between 100 and 140 for almost the entire year.

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How is CTL * FTP any sort of measure of fitness?

Start from the top. When planning out a season, there are a number of steps and I’ll use the list from Coach Joe Friel’s The Cyclist’s Training Bible 5th edition:
Step 1: Set goals
Step 2: Determine objectives
Step 3: Set Annual Training Volume (hours or TSS)
Step 4: Prioritize Races
Step 5: Divide Season into Periods (e.g. Base1, Base2, …)
Step 6: Estimate Weekly Volume (hours or TSS)

Using that framework to create an Annual Training Plan, the most basic volume measurement is hours. When you get to step 6, the amount of hours per week will vary based on the phase of training (e.g. base3 vs build2).

TSS improves upon hours as a planning tool, because TSS factors in both hours and intensity.

That provides a high-level plan. From that a detailed week-to-week plan is put together. If you are coached, your plan is likely more dynamic, personalized, and updated weekly or monthly. If you purchase a plan (TR subscription or from a coach), the plan is static unless you make adjustments.

So if someone else is developing your annual training plan, or you don’t have one and are just following a standard plan purchased from TR or a coach, then you can ignore TSS/CTL and just follow the plan.


Just do some math and plug in numbers.

Person A has an FTP of 2W/kg and a CTL of 50 because they’ve been training like mad, FTP * CTL = 100
Person B has an FTP of 3W/kg and a CTL of 40, well FTP * CTL = 120

100 < 120, person B is fitter.

You also might have this scenario

Person A has an FTP of 3W/kg and CTL of 20 because they have not been training as much. CTL * FTP = 60
Person B has an FTP of 2W/kg and CTL of 50 because they have put in lots of hours. CTL * FTP = 100.

You could argue that even though Person B has a lower FTP, they are “fitter” because they have more hours in, and would probably expect them to soon increase their FTP while person A is probably not doing all that well.

Again, imperfect, but it’s something.

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The math isn’t the issue, it is the logic. CTL isn’t a measure of fitness, so it makes no sense to treat it as such.


“ignores the context within which that time and intensity is generated.” Indeed.

Spanish Needle : 99 x 15 second bursts at 150% FTP. 101 TSS.

Now restructure the ride and smoosh all the bursts together so its 20 minutes at 40% FTP, 25 minutes at 150% FTP and 15 minutes at 40%. Still racks up 101 TSS, but an impossible workout*

Now, noodle around at 50% of FTP for a couple hours; 101 TSS.

*Pretty sure by definition and any testing approach, if you can do 25 minutes at 150% FTP your FTP is wrong!


How does comparing a workout that no one can complete to one that is at least theoretically possible to complete demonstrate anything?

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If you look at Strava, CTL is actually called Fitness. Not saying this means anything, as I think it is a terrible term. But clearly some people believe there is a relation.

Correct, CTL is not a measure of fitness. It’s a certain online training platform that went and called it “fitness” (and called ATL “fatigue”, and TSB “form”). It’s really straying from the original intent.

Similar to FTP being “hour power”… but that really is a can of worms.