I always feel like my CTL numbers are pretty low compared to everyone else. I peaked this summer before Leadville at 89 on intervals.icu and 91 on TP’s. Currently I am in low 60’s and riding about 6-8 hours per week and 3-4 hours lifting/walking. Training Peaks always seems to have a higher CTL for me than intervals for some reason.
This is only possible if your FTP is not set the same in both systems, or you have duplicate workouts (this happened to me) in TrainingPeaks.
Actually, I see lots of little differences between the two that add up over time. Especially if you include non-cycling activities.
Certainly shouldn’t be adding non-cycling TSS to a cycling TSS metric.
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But lots of people do
Lots of people do lots of things. Doesn’t make it right.
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You said it’s not possible. I said it is and explained how. Thats all. Not here to argue about right or wrong.
I suppose you’re right. I didn’t anticipate people would put non-cycling activities and then talk about their CTL. However, if it’s in both systems, I would assume it would be the same?
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There’s a methodology difference.
TP accounts for all activities so that a Gym session will go into the calculation
Intervals does not. Note that the “TSS” is between parenthesis, meaning it was the TSS, but 0 went to your fitness chart.
Also, the numbers in TSS for the same activity in TP are normally higher when it comes to off-the-bike training.
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Yeah, there was a lot of discussion a while back on the topic. I feel like “He who shall not be named” was involved since he came up with the metrics in the first place! There were a lot of people including their runs and what not, because even though it’s not intended for that use, it’s how they track their overall fatigue (right or wrong). I do include it as a data point so I have everything in both systems, but then have filters set up to show my “true CTL” for when I’m looking at my cycling fitness (or reporting my number in a thread like this). There are definitely differences in how TP and Intervals calculate the data for non-cycling activities, but then if you filter on just bike, they true up.
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We could also say “back in the good old days when xxxx was here…” 
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0
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I think that there is a use for CTL with multiple sports as long as you view it as a number that roughly represents overall load. Whether it is an accurate representation of the actual physical fatigue is a different matter.
For a rough example, take a power meter that is not accurate, but it is consistent. You can track your load, as it pertains to you, because the PM is consistent. But what you can’t do is compare those numbers to someone else who uses an accurate meter.
When I was doing tri’s, I had a CTL in the 150’s. Looking back, my swim numbers were grossly inflating my overall CTL….but I was using numbers consistently, so I believe it allowed me to track my overall load relatively well. But my numbers could not be used in comparison to others…and certainly not to single sport athletes.
Anyway, back to CTL numbers that can be compared, entering August I was around 100……but a number of issues put me on my back foot and over the next 2+ months, my CTL plunged down to about 35. Been back at it consistently over the last couple of weeks and I am back into the 50’s. Amazing what a single long ride with a 200 TSS can do for your CTL when it is so low. 
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FWIW, the good doc has been banned from every forum I have ever seen him participate in. Despite his knowledge and insights, he eventually veers off the rails into denigration and ridicule of people asking questions.
His removal here was part of the pattern, not a one-off occurrence.
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Even if this is true, a tiny transaction cost for valuable information, fact checking, references lists…etc. What a loss for this forum.
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Well said. I was trying to get at this, but you said it better.
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My FTP is set the same in both systems but TP picks up all my other activities (walking/lifting) which skews it higher. Thanks for the clarification.
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For those with CTL over 100 how many hours a week are you riding. Looking back at the calendar it looks like I was typically 11-13 hours riding per week in May, June and July prior to Leadville Stage Race and LT100. Biggest week was 16 hours when I did a 12 hour race June 1st. Typical week was a lot of zone two with 1 or 2 days of hard structured intervals. My CTL peaked in middle on July around 90.
I got to 100 on ~15 hour per week.
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CTL around 125 - 130 on 18 - 20 hours a week cycling