One big oddity with the above chart has to do with Stronglight tapers, which for our purposes means 1970's since those were the years of so many of them coming to the US.

I have many times measured such tapers alongside other tapers such as ISO, Campagnolo (both old and newer cartridge style), JIS and so on.

The Stronglight taper on a typical Competition bottom bracket is considerably smaller than Campagnolo's cup/cone spindle tapers, and smaller yet than any JIS taper.

Yet their chart shows it is larger, like JIS.

I've responded to other's posts about this over the years, as they had obviously sourced their info from Sutherlands.

I find it most easy to compare spindle lengths and tapers directly, whereby the accuracy of the measurement caliper matters not.

I encourage such comparison on the spot when choosing from possibly-compatible spindle choices, as all that is needed is a caliper, better yet with a locking feature which most digital and dial calipers have.

Setting the caliper at 13mm locked, two spindles can immediately be compared for how far that the taper passes through the jaws.

Alternately, perhaps for creating a database, I place the 3mm-wide jaws flat on a table top and then stand the spindle up on the table between the jaws.
Closing the jaws over the flats measures the taper width at the reference distance from the end of the spindle equal to the jaw thickness of approximately 3mm, so the same caliper can then be confidently used on other spindles being measured for the same database (or being compared directly for immediate use).

So there are two good ways of comparing the spindles before bolting them to a crankarm for final fit evaluation.

Lastly, I've measured several examples of Superbe/Mighty spindle tapers alongside the later cartridge-style, ISO-spec Campagnolo bottom brackets, and all of these tapers measure identical.
These are among the narrowest of tapers by the way, only Stronglight measures that small among non-Ofmega-made spindles.


Below, I was (over ten years ago) measuring a Dura-Ace 7400 spindle taper. Curiously, from memory, that number 12.9mm jibes with all of the JIS spindles that I have ever measured, and which tend to fall into a very narrow size range (despite many of them appearing to lack any final machining of the taper surfaces).
But as I mentioned above, for comparing measurement numbers, the spindles being compared really should be measured using the same caliper in the same time frame instead of looking at the numbers all of these years later!
And perhaps also, this might be a "pre-1985" Dura-Ace spindle because I can't quite make out the visible date code on it.
For comparison, numbers wise, the ISO and Stronglight spindles measure near 12.7mm, while the cone-bearing Campagnolo spindles measure just under 12.8mm
Tolerances on TA spindles can be so bad that I've seen different measurements between different pairs of opposing flats on the same end of a TA spindle!

Always check your caliper's accuracy before making measurements to be entered into a database (which is super easy to do using any decent grade of new bearing ball having a known size).