Iām happy to try to elaborate in the goal of full understanding (for myself, as well.) If Iām wrong, Iām happy to learn something new. Nothing Iāve read so far has flipped a switch for me in understanding my error.
In no particular order other than the order of how my mind works, hereās whatās in my head:
OP basically asked if leg strength is worth tracking (and logically, training.)
Cog says āItās not about the force your muscles are producing,ā but about longer term ability to keep producing it.
I agree with this wholly in general (IE, you donāt need muscle hypertrophy to push a big FTP a long time).
Also, I feel that there are times where high force is a factor. The start of a poorly geared sprint, or when briefly pushing a very tall gear over a the top of a climb, or responding to an unexpected attack (Again, when incorrectly geared.)
I offer, and fully agree, that when properly geared, it shouldnāt be a factor. Also, these moments are likely brief, as you can respond by shifting. But in the real world, the force and RPM equation of wattage occasionally is skewed much harder to the force side, and itās not 1/1mm. And for that matter, while those moments may be brief (a suddent attack), the impact may extend far beyond the 2 second instance (getting a gap and losing a wheel)
Furthermore, Cog states and agrees that strength does impact ability:
ādifferences in strength only account for ~50% of the variation in the time required to cover the first 15 m.ā
Soā¦ we agree that sometimes, strength matters. This is where I guess the breakdown is occuring for me. Iām positing that strength matters in some situations, and I feel like whatās being responded to is essentially that Iām arguing that strength is crucial in cycling, or that Iām arguing it makes an impact in areas broader than what Iām referring to. Cog, I fully agree with you that in the vast majority of cycling, strength (as you defined it) isnāt a factor. But as you said, there are times that it does matter. I accept that this could just be the break: a section of the data that I think isnāt actually uncommon, and other people view as an extreme edge case, and it might just not be worth exploring and I neednāt have brought it up.
What I donāt understand is saying that the data indicate times where it makes a difference, and then arguing that those differences donāt matter. Put another way, I would potentially argue that the first half of that is irrefutable by the data, but the conclusion drawn is not purely irrefutable or impervious to disagreement. Cogās and my interpretation of the data can be different even if we both accept full accuracy in the data.
To be very transparent, Iām trying hard to not be a contrarian āACHSHULLYā person who comes up with one extreme edge case and argues it to death as though that disproves the 99.999% of times. I do think, though, there are more cases that 1 in a million in which the ability to suddenly throw down high force is simply a factor in real world cycling. Perhaps Iām wrong, and thatās ok. Itās not the first and wonāt be the last time.
In my day job and in my friends, Iām lucky enough to be surrounded by a strangely high percentage of masterās and PhD level folks. Iām very lucky to be in an enviroment where I often donāt even understand the title of their thesis. I love to learn from experts. Iām also lucky enough that they are extremely willing to browse edge cases and explain implications. I find that valuable, and very interesting. Getting into a 2 day disagreement with the preeminent authority on cycling physiology was not on my christmas bingo card. 
No hard feelings, Andrew, I hope.
I think youre saying your edge case is you are at 50 rpm getting a feed and someone attacks at 400 watts. Now you dont have time to change gears and you need to muscle 600 watts at 50 rpm to close the gap. Weāve all been there and thats a common occurrence in a race -nobody is denying your point What Robert and Cog are saying is that at 50 rpm and 600watts to close the gap your leg strength required is equivalent to what any off the couch untrained athlete can put out. If that statement is wrong please correct me.
I liked Roberts rule of thumb to derive torque by taking power in watts and dividing by rpm/10 to get torque. So how much torque are you putting out in your chase? Well its120Nm or torque. So lets divide by .172m crank length to get force which is 700N. Thats 160 pounds force. So according to Robert and Cog, if you can do a 1 leg squat you have more power than you need. And thats maybe for half second until your rpms increase and that force drops linearly with rpm. So even your max half second force is something you already have without needing to lift even a pound of weights in the gym.
In actuality 600w is too high and the rpms i picked are too low to be practical but trying to capture your point.
Youāre right thatās a circumstance Iām envisioning.
Iām actually envisioning closer to the 1000 Watt range. So for that scenario, but also with a slightly more realistic 65RPM the napkin math is appx 147N. I run 170mm cranks, so thatās 864N, which is ~193lb.
- Iām ~170lb depeding on the holiday, and I donāt think I could go do a 390lb. squat. Given my left leg injury, iām quite sure I could not do a 193lb left leg push. Iām strength limited in this scenario.
- Continuing that logic, if that person could briefly (anaerobic, 3-5 pedal rotations) push another 20lb, then for the same RPM and cranks, thatād be a force of 947N at the pedal and 161 at the hub. Thatās a delta of almost exactly 100W. 100W in the first 3-5S of a sprint is enough to gap.
And thats maybe for half second until your rpms increase and that force drops linearly with rpm. So even your max half second force is something you already have without needing to lift even a pound of weights in the gym.
But you donāt shift in a sprint, especially an unexpected one.
I think I struggle to understand how it could be argued that 170lb/750 is āenoughā force for cycling. If someone were to put down more, theyādā¦ go faster. Put another way, if a 140lb cyclist put down 140lb/620N, they wouldnāt go as fast in that sprint. That person would be benefitted by applying more force (if they were in a situation that made shifting and spinning up a disadvantage.)
I think youāre saying strength matters in trivial circumstances (for example, 0.01% of the time you ride). Cog is saying donāt bother to train it because itās not worth training such a low frequency event, especially since training anything in particular requires you to forfeit time spent training more profitable things. I think any reasonable person would agree.
I guess. Iām not a prideful enough person to ride my argument into the ground, I just genuinely donāt understand. Maybe itās because I actually am a weaker strength rider, but there are not at all infrequent times I want to be able to push more force into the pedal, and canāt.
Personally, I still donāt intuiteively understand the push back against more strength when the math I posted above isā¦ not rare for a sprinter. People push 2-500 watts higher than that and that would only stretch the delta out further.
Honestly though, Iām kinda tired of the back and forth on this. I think the math shows there are times it mattes, Cog has said there are times (very rare, to his positionās credit) that it matters, and everything else just comes down to: Itās up to the individual if itās worth training or not. Iām not trying to convince anyone to do anything. My position is clearly in the minority, and Iām content in taking the L and just moving on.
Im not saying 390 pounds. The math is saying if you, at 170 pounds can do a 1 leg squat with a 20 pound weight right now then you are fine for 1000w. Im pretty sure you can do a 1 leg squat with no additional weight in the worst case.
1 leg squat x 2 = squat. (technically, we should probably be saying leg push or something because squat includes a lot more than legs, but I think we both get what each other means.)
And youāre right:
at 170 pounds can do a 1 leg squat with a 20 pound weight right now then you are fine for 1000w.
But if that was my absolute limit, and I wanted 1200Wā¦ Iād be strength limited. Thatās my point.
Peter Saganās coach in 2018 explains it better than Iāve been struggling to:
"Sagan, and all our riders usually do gym sessions focused on improving their strength. Weāre not looking for muscle hypertrophy but an increase is maximum strength of the muscles used in the power stroke," Vila explained to La Gazzetta dello Sport.
Riders, especially sprinters, often work in the gym to boost their strength but rarely keep up the strength work during the season, preferring to focus on road training. Vila is convinced this is a mistake, with even a Giro dāItalia contender including gym work in his training.
āItās important to work on maximal power because racing and resistance training on the climbs (Sfr) trains the ability to push at a certain power but does not train maximum power. Higher power gives you a more economic pedal action at threshold,ā Vila said.
āDuring the season the squat is one of the preferred efforts. We do four sets of four efforts with an 80 or 90 per cent load, carefully controlling the speed is high.ā
Peter Sagan shows how he boosts his power with gym work | Cyclingnews
i thought your point was out of the right gear? in which case you dont need 1000w to catch up and if you did you have plenty of strength. this is well within 99.99999 percent of cases.
Well, I donāt understabd. I would try to clarify, but I think at this point, when 99 people out of 100 think Iām wrong, then Iām probably just wrong. Honestly, Iād love to intuitively understand where my error is, because I still donāt see it, but at this point Iām just gonna throw up the L and assume Iām wrong somewhere and just move on from it. Appreciate the discussion, though.
I donāt think thatās the case at all. I think a large number just donāt know, and just as large a number donāt care. Personally I do low cadence big gear tempo / SS work as part of my training. I feel it helps. Explanation as to why Iāll leave to others to try to work out.
Youāll have seen that exercise physiologists often have strong opinions about things. These strong opinions can be contradictory. This suggests that the science of physiology, isnāt as settled in some areas, as some of the strong opinions suggest.
Iāll go back to what I do. If I feel something is helping me Iāll keep doing it. What I wonāt do is argue till Iām blue in the face as to why.
This is why I think coaches give better training advice. Theyāve seen what works, for example most coaches agree strength training helps most people.
Can you elaborate on the relationship of low cadence - High Torque - Lower Heart Rate, for a given power target? Thanks.
Not that it matters in the least, but I would hypothesize that HR is sometimes lower at a lower cadence because of 1) lower O2 demand, and 2) less feed forward activation of the cardiovascular control center of the brain.
I encourage anyone wishing to better understand the issues being discussed here try to dig up a copy of Scott Gardnersā ACSM presentation back in 2006. Using his future-and-now ex-wifeās Victoria Pendletonās data, he showed how when she focused on resistance training, it lifted the far right end of the torque-cadence relationship, but had limited effect of maximal power, which occurs at much higher velocity. She/British Cyclingās other sprinters still spent plenty of time in the gym, since resistance training induces potentially beneficial adaptations other than increasing strength (e.g., increases in synchronicity and RTD). However, pursuit of greater strength wasnāt the goal, for the reason indicated above.
Finally, note that none of this has anything to do with the OPās question, which was about fatigability/fatigue resistance at much lower torque/power.
I agree on the sequence part. Those are my partially-quoted words, not yours, so I may be off in my reasoning or how I understood that commentāI draw pictures for a living.
I couldnāt find what RTD means in this context, what is that, @The_Cog ? Cheers
Most coaches are full of it as trainers, making things up, repeating falsehoods they have picked up from others, etc. Thatās why you get people saying that they, e.g., do āover undersā to increase ālactate shuttlingā.
Even Hunter Allen once told me that he had no real clue how to help a particular client, so just threw different things at him and bluffed that they would work.
As I always pointed out during the USA Cycling Coaching Education clinics, you donāt really have to know much about ex fizz to be a good coach. Just stick with the tried-and-true, donāt go chasing fads or magic bullets, and focus on other parts of the job, e.g., motivation, organizational skills, teaching tactics, etc.
Rate of torque development. (All the rage among the sports and conditioning types.)
Quoting from
Under resting conditions, oxygen extraction ranges between 20% and 40%. During heavy exercise, approximately 70ā80% of the oxygen delivered to the active muscles may be extracted.
You could hypothesise that the more muscle is active (as in low cadence same power) the higher the efficiency and thus the heart doesnāt need to beat as fast as the oxygen for that extra active muscle is already available in the blood passing by in the capillaries.
You have more active muscle cells taking up oxygen at a slower (individual) rate vs less active muscle needing to extract oxygen at a faster (individual) rate. How fast can the oxygen diffuse across cell membranes in muscle?
Imagine 6 riders riding past 10 helpers trying to grab 10 water bottles. Then imagine 10 riders riding past 10 helpers and grabbing bottles. Which group of riders manages to grab the most bottles? Now imagine the bottles contain oxygen.
Layperson alert 
