What came first: The chicken or the ashkenaz tefillin knot?

You men in the audience know what I am talking about. The halacha says that the knot on the arm tefillin needs to touch the box, but ashkenaz tefillin are designed so that the knot doesn't stay put. In normal use, the knot is forever sliding away from the box. Most of us use a piece of sinew or a special knot to keep it in place; the rest of us spend davening readjusting.

So what came first? Ashkenaz tefillin or the rule about the knot? My own, ignorant and speculative hunch is that the knot rule is another one of the Ari's late additions*. Does anyone know for certain?

* In honor of yesterday's public fast, let's discuss two other Hasidic reforms:

(1) Hasidic women don't observe the minor fasts. If you ask, they'll modestly look away and send their husband or older son to say: "It isn't our minhag (custom) to fast, accept on Tisha B'av and Yom Kippur." Can anyone on the inside comment? Is this a real minhag, a minhag shtus, or a concession to the fact that an overwhelming number of Hasidic women are usually pregnant or nursing?

(2) Hasidim don't say "Avinu Malkaynu" on public fast days, reserving it for the 10 days of repentance alone. That's really pretty cool. They finish davening a few minutes earlier, yet in every other way their prayer service looks just like Judaism.