Hey Roy,
I love the armbar triangle set up you demonstrated. Definitely adding it to my toolbox. My question is this- I havent had a chance to try it in a live roll, but I imagine it would difficult to grab under an opponents' calf since most of the time were taught to posture back. Any tips for getting our opponent to raise up a little?
If someone is posturing back forcefully, then the armbar is not the best attack at that moment (you might consider a hip bump sweep). A better strategy would be to break down their posture first using the power of your legs in order to expose their arm for the attack. Once you have the arm cinched up you can worry about getting under the leg to help pull you into good finishing position.
It's often useful to grab under their leg to help turn your body as they begin to stack you. This way, you can redirect their force into a sweep, and because they're stacking you, their legs are extended. If they are posturing up and leaning back, your efforts are better focused on either pulling on their head to break posture, or using your hands to push off the ground behind you and sweeping them to their left or right rear corner.