Campagnolo recommends a completely different method. Just sayin'...

link to method please, and different to which method?

Go to 7:58 in the video below (and it's also in their printed manuals). They base it off of the gap between the chain and the jockey cage when in small-small.

https://www.campagnolo.com/US/en/Sup...ical_groupsets

I see. Thanks for the link.
I still feel its a really bad method to tell people about.
I guess because I'm a long time tourer, and in the touring world, it is rather common to change your granny chainring to a smaller one, an easy inexpensive way to lower gearing--so if someone uses the small small method, they risk getting into some serious doo doo with a big big situation.

and in touring, nearly always with triples, the small ring is used for climbing med to steep hills with a very heavy bike with a load, so riding in the small small is just not done that much, as we get out of the small ring fairly quickly usually--and even then, a slight bit of rub is all that happens, unlike with a big big snafu that can completely frack a wheel, spokes, derailleur, hanger etc.....

Big-big, small-small and Campy's neither one chain sizing methods all work as long as you stay within the rear derailleurs wrap capacity. That point is often overlooked when recommending alternates to big-big.

I do admit that the wrap capacity is something I often dont think of, only on the rare times that I change stuff on a bike, and then read up on to refresh my memory and get the specifics of the rd, model number , so be sure of the wrap. (this is pretty rare to be honest, so I really do need to refresh my memory on the whole thing).

When I change a chain on an existing system on a bike that is known to be setup right, I just do the big big not through the pulleys+2 technique to know where to take off links (and even then, I check up on the technique again to be sure I don't make a mistake)

That makes sense. I certainly wasn't trying to imply that their method was somehow superior, just pointing out that that's what they recommend for their products. And I don't think Campangolo have any modern day components specifically intended for touring use.

Anyway, I believe the reasoning for their method is something along the lines of Campagnolo believing that a slightly slacker/longer chain makes for smoother shifting. And they still set the bar...

I guess the main thing is that no matter the method, you just dont want to have a chain thats too short for that unlikely, but possible, big big shift.

Weird to quote myself, but I wanted to update this. I just used the Park calculator again on a 1x11 with 32x11/42 gearing and it was off by an appreciable amount. I added back in two lengths and it would probably be better off with 2 more yet.

Anyone who doesn't understand wrap capacity can get into some kind of trouble. The little/little method that Campy recommends also assumes that you're smart enough to read Campy's stated limits on chainring and cog sizes and the total wrap capacity. If you had a stock 30T small ring and changed to a 28T, there would be no need to change the chain length, since the change is less than 4T. If the chain hangs loose in the small/small, you have exceeded the RD's wrap capacity. That's OK because you should never use it. If you change to a 26T, then the chain will hang loose in several of the smallest cogs, but you would still not need to shorten the chain. If you did, then most likely you would have to avoid the big/big.

When Campy made triple drivetrains, they had both medium and long cage RD's that would work with a triple, but only the long cage would work with a 29T large cog. When the chain length was set using the proper 30T chainring, it would work perfectly. You would still NOT shorten the chain with 26T chainring, unless you're willing to avoid the big/big combo. Some people deliberately use a chain length that won't wrap the big/big, knowing that they will never use that combo. Most often you'll just get a lot of noise and the shift won't happen, if you accidentally try it.

Exceeding the chain wrap capacity is not that big of a red line, as long as it's a tooth or two and you accept that "it might not work". When it does work, you're good to go with no ill effects.

I'm told it's because the manufacturer specs tend to fudge it by a slight margin to provide an extra margin of safety. Maybe, though to me a capacity limit should be the limit period and they should call it a recommendation instead, but it is what it is.

Im betting the extra leeway is there to make installation and adjusting less finicky. It should just work, and it does if you adhere to spec.

There must be 1/2 inch or 2T of excess wrap to accommodate chainstay lengths that fall in between perfect chain lengths that are not exact increments of 1 inch.