Syncopations are in fact the siteswap tricks that you can do while passing.
Classic siteswap rules apply most of the time. If on a given rhythm J1's normal passes are straight singles, then doubles are crossed, triples straight, ... and conversely if J1's passes cross.
Some syncopations are trivial, these are the one that only happen on self throws.
On a 4-count for instance, there are
three consecutive selfs per cycle, and you can write these as 333. But you can
replace this sequence by any 3 object siteswap of length three such as 441 or
531. You can also use synchronous siteswap as long as you can do the asynch-synch
and synch-asynch corresponding transitions.
But syncopations that aply to passes are far more interesting.
Let's look an example first with J1 and J2 doing a 3-count. Now pause the passing when J1 is passing from his right hand to J2's left hand. This pass is a single noted 3p.
Now let's go back one beat: J1 is throwing a self from his left hand to his right. Let's replace this self by a double pass to J2's left hand, siteswap-wise it's a 4p and it's a crossing pass. One beat later, the double pass is still flying high between J1 and J2, J1's right hand has no club coming in and therefore has a hold (steswap 2). One beat later again, J2 is catching the double at the same time that the normal pass would have arrived, so for J2, it's as if nothing happened.
3-count with early double
Early passes do not affect the sequence of throws of the catcher, it's the thrower who has to anticipate so that the pass arrives at the same time as normal: 1 beat before for a double, 2 beats before for a triple, ...
Late passes are so-called because they're coming late on the receiver's side. The one throwing doesn't change anything but just replace his normal pass by a double or a triple. The receiver must wait for the pass, but must also make sure that his next pass is still on time.
Let's take teh 3-count again, with J2 now doing a late double instead of a normal right hand pass. The doubles crosses and arrives in J1's right hand one beat late. The double takes the place of J1's usual first self, which he didn't throw because no club was coming on the left. J1 now does a first right hand self (usually the second self) in order to catch the pass, then does the next pass. Had J2 done a triple, J1 would have done no self, he would have passed in order to catch the triple.
3-count with a late double
Forced passes are syncopations that compel the receiver to modify his side of the pattern. Late doubles are a very basic exemple of such passes. But it can get a lot more complicate when you try some sequence of throws that are usually forbiden, but become doable if the receiver knows how to react on time.
When you're doing (normal, early or late) passes in the middle of a siteswap sequence, you reaching the next level of complexity. Let's see an exemple with a 441 in a 3-count:
3-count with 44p1
Upon catching a pass, J1 does a straight self double (4), followed by a crossing double pass (4p, this is the early double we've seen before), and by a handacross (1). The pass is included in the siteswap sequence. You can do this continuously and create a new pattern that bears no resemblance at all with the 3-count, especially if your partner is doing it at the same time. Strong, no?
Syncopations can be done one after the other continuously, whatever the rhythm. You can also do them in patterns and feeds with more than 2 jugglers. Take care though with late and forced passes and make sure your partner knows how to handle them. If you have a doubt, just ask or only use early passes that will arrive on the same beat than the normal pass.