Two-Handed Synchronous Siteswap
In two-handed synchronous siteswaps, both hands throw on the same beat.
If you juggle 4 balls asynchronously and synchrously and compare, you will notice, that the rate of throws has halved for the synchronous pattern. This has happened because throws are still at the same height, but throws of one hand were between the throws of the other hand and they now both happen at the same time, while nothing happens at the time where the other hand had thrown. We group the siteswap numbers that happen together with paranthesis like this:
To keep the siteswap numbers the same compared to vanilla siteswap, the custom has become to still count the unused beats (or to count both throws, even if they happen at the same time). As a consequence, every throw happens two beats at the earliest and there are only even numbers in synchronous 2-hand siteswaps. So
(4,4) is actually the synchronous 4-ball fountain.
Because now several hands act on the same beat, it has become necessary to mark where a hand is throwing. This is done by writing an "x" to throws that go to the other hand and nothing, if throws go to the same hand.
would be the pattern "wimpy", a synchronous 4-ball pattern in which all beats cross.
You can still apply all the rules and math as in vanilla siteswap, only you have to count both throws/beats that happen on every paranthesis and use x to mark crossing throws.