Andrew Smith is a 3rd-degree BJJ black belt based out of Richmond, VA (Revolution BJJ). He runs BJJ Path, a video tutorial website.
The Kimura Train
By now, you've hopefully gotten pretty good at catching the Kimura, whether from the half guard, knee cut, or standing position. The great thing about this grip, after all, is that so many people who understand jiu jitsu (at least on a solid fundamental level) will fall into the trap of leaving their elbow open, simply because they're responding in predictable ways to keep you from getting what they perceive is a better position. After all, if you get the underhook on top in half guard, you're probably going to pass their guard, and so on. Here, let's get a little more involved with one specific scenario: you're going for the knee cut pass and catching the trail arm, but they're entangling your leg with their legs. Time for "The Trade" to go into effect.
Putting Things Together With "The Trade"
Once you've gotten proficient with the basic floating pass stuff, then worked your way up to catching the trail arm, it's important that you are able to put all of the positions together seamlessly. If you're passing the guard in the gi with a knee cut pass, one great way to bait the person into coming up for you is to drive their collar toward the mat, keeping their weight on their elbow as they try to come up on top (a very, very common reaction). Think of this first phase as the initial set up. Next up, you're going to need to move to phase two of catching the trail arm. Let's call phase two "the drape." You'll want to make sure your stomach is draped over your partner's head, not your chest, or else you won't be able to get the initial Kimura grip. From here, you're just looking to punch their elbow forward and roll over your right shoulder, but what will often happen as you go to pull your leg free is that your partner will use their legs to keep your leg ensnared. After all, you started with your foot trapped in a knee cut pass position. The only thing you need to do in order to turn this position into "The Trade" is to pass your arms over to the other side of your partner's body. In the video shown here, I sit forward in order to create enough room to pass my upper body over.
Moving to The Trade
Here's another look at the initial trail arm catch. Once again, I end up with my leg stuck in a sort of inverted half guard (or "backstep" position). No problem—this is really just about 90% of the way to The Trade. All that's left to do, in fact, is to drive off of the ground in a sort of backwards "float" position. Now your right leg is trapped, and you're fully on top of your partner's upper body, with your neck and shoulder on the ground, looking back at your partner's hips. After using your right foot to step onto your partner's knee, use the moment when the left foot comes free to hook your partner's hip (lest they simply catch your other foot!). From here, you can often simply mule kick to side control to break your partner's grip (and if not, you'll have plenty of options ahead from previous experience).
Keep in mind that the goal should still be to free your leg during the transition, too. If you can avoid having your partner trap your leg at all, that's even better for you in terms of completing the pass with maximum efficiency (and although this sequence might not look like guard passing in the traditional sense, it certainly is). If your partner doesn't grab your leg immediately with their legs, simply curl your foot in toward your butt and don't allow them to have it! This will save you a lot of time and energy. In this video, I remind you that you can keep the person from coming up from an "El Gato" style pass by curling your hand upward, saving you a lot of energy during a crucial transition (where you don't necessarily have to be faster than your partner).
The ultimate goal is always a seamless transition from one position to another, and going from the trail arm catch right into The Trade, right into El Gato or the floating pass are all great examples of this process. That is, in a nutshell, jiu jitsu!