My understanding is that it doesn’t matter. O.67 of YOUR FTP for 5:30 will lead to you scoring 247 TSS points, and me doing 0.67 of MY TSS for 5:30 will lead to me scoring 247 points as well. TSS is based on how hard each individual is working as a percentage of their FTP. Hope that makes sense to you.
I understand that bit, so 2 people ride 5.30, one does it on 100 watts and the other 200, one is riding at 67, the other 134 and both will have a TSS of 247, but its a pointless table, unless you know what your FTP is, and what your time for the bike is.
So I know my FTP - its 233, but I’ve no idea what my IM bike is, so I can really use it.
Time will depend on course, weather conditions, your CdA, (how good is position on bike) AND not biking beyond your ability (FTP).
Point of chart is to show the slower you go, the lower the IF, or percentage of FTP you should ride to insure you have a shot at a good run.
The faster you go, the higher the IF, and you can ride at a higher percentage of FTP and still have a good run.
And yes, that chart is rather meaningless unless you know a whole bunch of things - (see first sentence) - but it is a worthwhile guideline.
If you have been training with a power meter for any length of time, you should have a pretty good idea of your FTP and how fast you move at a given percentage of that FTP - use that to estimate your IM bike split and see how it matches up with chart. Adjust IF accordingly if you want to use chart as pacing guideline.
The chart assumes that a person riding a 5:30 should have the same TSS as someone that is riding 4:30 and 6:30 which is IMHO, the wrong way to use TSS. It says to me that if you are able to ride faster, then you can ride at a higher percent of your FTP which we know is the wrong way to have a good Ironman run
With that said you can estimate TSS with your long rides on similar terrain. If you do an hour as 67% of FTP you can find out approximately how fast you would be going during your event. From that you can estimate your Ironman bike time to within 15 minutes.
With that time you can estimate TSS at that intensity.
bestbikesplit.com has a TSS constrained model that can do what you want. Give it a TSS and it figures out the power that will get you through the IM course as fast as possible at that TSS.
I understand that bit, so 2 people ride 5.30, one does it on 100 watts and the other 200, one is riding at 67, the other 134 and both will have a TSS of 247, but its a pointless table, unless you know what your FTP is, and what your time for the bike is.
So I know my FTP - its 233, but I’ve no idea what my IM bike is, so I can really use it.
The only way this works is if you know that if you bike 67 watts (your example) for 112 miles it will take you 5:30. It’s an iterative process. Bestbikesplit does it for you. Before that model was around, you would assume a power you should ride (based on FTP and IF) and then use some other model (several out there or poll people to see what power they used to ride a specific time, which isn’t very precise) to see how fast you would ride the course based on that AVG power and then calculate TSS. Hopefully the TSS was in the range that you feel comfortable running off of. If not, adjust the IF and power and repeat. Like Jack said, bestbikesplit does the math for you now. Pretty cool.
It says to me that if you are able to ride faster, then you can ride at a higher percent of your FTP which we know is the wrong way to have a good Ironman run
Jaret,
So are you saying that pros like Ben Hoffman shouldn’t have ridden with an IF of ~ .80 which gave him a TSS of ~ 288? While I agree that there may not be a special “magic” in the keeping it below TSS of 300, it does give a reasonable guideline that has worked for many folks. Since TSS values are a pretty decent proxy for glycogen use and glycogen stores are paramount to being able to actually run the marathon looking at them gives at least some way to judge potential fuel usage.
It says to me that if you are able to ride faster, then you can ride at a higher percent of your FTP which we know is the wrong way to have a good Ironman run
There is some % of your FTP to ride at that will get your fastest ironman overall time. Any more, or less than that, and you will go slower.
It does make sense that a faster rider can ride at a higher % of FTP because they will ride for less time as well.
All of the pros I’ve talked to, (3rd tier) say they normally come out closer to 250 than 280 to have a good run. Perhaps it’s different with a tier 1 pro.
Then the older age grouper, say 50 year old woman with an FTP of 180 will still ride near 70% of FTP but have a TSS higher because they will be on the course longer.
"Whats the FTP though that needs to be obtained to allow 67% of it to result in 247 - I can’t figure that bit out
The math is quite straightforwards, what I can’t see, or appears to be missing is the starting FTP that resulted in that table? "
Two very good questions that are difficult to accurately answer as there are a lot of variables that come into play. BestBikeSplit can come close if you can accurately estimate conditions, your “aeroness”, etc…
Where the chart really helps (and what it is designed to do) is with assessing a past performance which can be used to figure out your power level based on the data previous race(s).
Also keep in mind that TSS is Normalized Power. But you actual time tends to follow average power more closely. So a more effective ride, is one that’s smooth so that your average power is as close as possible to your normalized power.
For example, I rode a VI of 1.05 at IMWI. I now believe that I would have gone 1-2 minutes faster if I have rode a 1.03 and gone a little easier up the hills and slightly harder on flats and descents. Mt AP would have been higher, but NP stayed the same… and TSS dropped very slightly since I rode 1-2 minutes less. Since the physiological stress is based more on NP, the smoother you ride, the more average power you can put out, which is the actual work/energy output. Do more work, and you go faster. However, there are some opportunities to gain time up hills (less wind drag, so adding power yields more gains than on a flat road) and with headwinds (it’s a fixed distance, so riding harder means you spend less time riding into the wind).
I think the pros are normally closer to 250-270 I think because they have to run faster to be competitive, usually running closer to the middle of zone 2. Age groupers due to the total time involved are more limited by energy systems and lack the mileage and have to target low a zone 2, upper zone 1 run pace.
Plus I tend to think TSS doesn’t exactly scale perfectly for someone with an FTP of 220 vs a pro with a FTP of 350-400. I think there are some different physiological limitation I think occurring. Then again, go look at Lionel Sander blog and you start to think that some freaks of nature have a lot fewer physical limiters than other. That guy could probably be the best ultra runner in the world after he gets bored with triathlon. They need to add a ultra IM distance (5k swim, 200mi bike, 50mi run) I think, to really showcase his potential. Actually, that deserves it’s own thread.
But then you are assuming that you can actually use TSS for that application.
Yes, the idea of using TSS as a constraint for IM pacing, does assume that it makes sense to use TSS as a constraint for IM pacing.
I mean, it probably makes slightly more sense than using NP which probably makes slightly more sense than using AP
Any of these could be misleading with a twisted enough edge case though.
I personally think the TSS approach is kind of overkill. Practice this in training, use data from past races, set a normalized power goal, adjust accordingly if course is super fast or slow or hot or cold, and only use the goal as a guideline not a rule o be followed robotically.
Plus I tend to think TSS doesn’t exactly scale perfectly for someone with an FTP of 220 vs a pro with a FTP of 350-400. I think there are some different physiological limitation I think occurring. Then again, go look at Lionel Sander blog and you start to think that some freaks of nature have a lot fewer physical limiters than other. That guy could probably be the best ultra runner in the world after he gets bored with triathlon. They need to add a ultra IM distance (5k swim, 200mi bike, 50mi run) I think, to really showcase his potential. Actually, that deserves it’s own thread.
When Rick Ashburn, Chris Whyte, Patrick McCrann, and I brainstormed that table back in late '07, early '08, our line of reasoning was:
If TSS is a measure of the stress applied to a cyclist during a ride…and the objective of the bike is to set up the run…and there is no such thing as a good bike followed by a poor run…then intuitively there must be some level of stress where a good bike ends a poor run begins
So we looked through our athlete files, our own files, and our experiences as guys who had done a lot of clock punching on bicycles and determined what TSS numbers seemed to work best and where a good day started to turn into a bad day, etc. From this discussion we created the table…in ~ December 2007.
Since then we’ve learned a lot, refining these ideas, which it looks like a lot of the participants in this thread are aware of and are pointing out. Internally with our team we have a more nuanced discussion of this table and the stuff that lives around it.
I don’t know about becoming the best Ultra - I sat next to Killian Jornet in Cham in August, and I think it would take some doing to give him a run for the money.
It has to be nauseating to be running with him - as he tends to like the company, and then when he’s good to go, he just takes off and leaves the rest of them for dust and its not malicious, he just likes chit chatting apparently…
So long story short the faster you are the higher IF you can hold because you spend less time on course accumulating TSS.
TSS is only one piece of the big picture (plus it’s only as good as the accuracy of your FTP). There are a lot of ways to accumulate 250 TSS and not all of those rides will leave you feeling the same way.
