BJJ Globetrotter Camp (Sportoase Leuven), Oliver Geddes , Leuven, Belgium, 22/06/2016
The double under pass has various names: I've tended to refer to it as the 'stack pass', or 'double underhook' pass, which relate to the 'single stack' and 'single underhook'. The principle is the same with all of them: elevate their hips, get a cross collar grip, crush through to side control. Looking back through my blog, I haven't been to a class on it in a long time: the most recent entry is a class from Jude back in 2007. More recently, I've taught this myself a few times, so I can cheat and use that as a skeleton to help write this class up. ;)
When I teach it, I go from closed guard. As soon as you can create enough space in their closed guard, slip your arms underneath both legs. Grasp around the outside and secure a gable grip (palm to palm), or an s-grip (four fingers clasped together). If you prefer, you can instead grip their trousers and lock your elbows, or indeed their belt: the problem with those grips is that the loose fabric may provide them with enough space that they can make room to escape.
The latter is the one Oli went with when he was teaching this, staying very tight. He also interestingly mentioned a funky elbow lock you can do to counter: writing this up some time after the actual camp, I've now been to a class at RGA Bucks which was all about countering the double unders with a whole bunch of submissions (I haven't written that up yet either, but it's on the list ;D).
Whichever grip you prefer, you now want to stack your opponent, driving forward off your toes. Before that point, Oli talked about sprawling back to recover your position if they started getting legs under, as well as doing a sort of 'hip switch' if they were able to hook your leg. To get them in position for stacking, the two basic methods are to either pull them up onto your hips using your thighs as a ramp, or move forwards so you're close behind them and they are rolled up onto their shoulders.
Oli had a third version. He steers them in a direction, pulling back and down on one side, in order to get his shoulder behind the knee. That's when he starts to stack them, getting the lower hand in the middle by their lower back. Once you've got them stacked and have reached for their opposite collar, the aim is again to push their knee right into their face. You can keep them stacked by putting your knee into their bum, while you continue to shift around.
If you can't grab the collar, your can grab the shoulder, or you could also reach behind their head. An even tighter option is to reach all the way behind their head and grab the shoulder. In that situation, be careful you don't start neck cranking with a 'can opener' (a crude technique from closed guard where you pull their head towards you), as that's illegal in most competitions for a reason.
I normally establish a wide base with my feet, Oli's version looks easier, as he stayed fairly low. Either way, it is important to keep maintaining heavy downwards pressure throughout this pass. Keep pushing until eventually you drive past their leg and transition to side control: don't raise your head, just keep pushing until you slide past, nudging with your shoulder if necessary.
Oli didn't spend much time on locking his hands together, as he pointed out that if somebody is good, they are not going to let you do that. He therefore sticks with grabbing the top of the trousers on either side, by the hips. A variation is to get both hands to the middle of their lower back, then do a powerful motion to flip them up. As Oli emphasised, this isn't going to work well on somebody bigger than you. He then used his head by the hip to move round and get the pass.
There was a weird leglock you can do too if they block with their leg, which looked a bit like the way you armbar from a crucifix when you're still attacking the turtle. You lock around their leg, then stretch your body, driving your hips down. Most of the time, this isn't to submit them, it's to get them to move their leg out of the way so you can complete the pass.
Bring your hips high, using your arm to punch that same leg your were controlling away, in order to pass. Be sure they can't shrimp away, as that will mess up the pass. That's where your other arm comes in handy, driving their hip to the mat. Your head is also by that far hip, adding more control.
Don't forget, you can also go to top half guard if you can't get past their leg. Finally, be wary of the reverse triangle as you pass. Keep solid control of that leg, so they can't push your head through. I like how he described "removing options": it's a slow, steady pass, taking away their options until you've got all their escape routes covered.