Two options that I have pulled off a bunch of times. Both moves are done with gi in mind by the way
-Lets say you are controlling HIS right arm with your left hand with a good grip. When your right leg is tossed over, Place you left foot on the mat and escape your hip hard to your left. When you do this your shin (around your ankle area) will fall into the crook of his right arm. Your right arm will be stiff arming his hip to prevent him from coming around and will also assist in your hard hip escape. Be sure to use a "false" grip..meaning thumb against your fingers because if he does a wrestling hip switch your thumb will snap. Figure four your legs and proceed with a bicep crush by reaching under his tricep with both hands and kicking your shin away
-If he really tosses you, go with the momentum and roll to your knees, while maintaing that grip, you will be both facing the same direction. I like to glue my left leg along his (right) hip and post with my right arm to moniter his movement. Proceed with a rolling omo plata or roll into triangle.
Renzo actually adresses this at some of his seminars. He will cross his ankles, and push his heel into the opponents spine, this actually will break posture. Then he puts his right hand on his right thigh(midway between knee and hip), left hand on left knee, and straightens his arms. When this is done, he can't be folded up and stacke, and the opponent cant lift the leg. From there he will start to work into finishing.
dude,
your friend's partner gave up the triangle and your friend never really
reacted.
as soon as the dude underhooked his leg giving up the triangle,
your friend should have crossed his legs OR grabbed his right leg with
his left hand.
when the guy posted his left foot near your friend, your friend
should have immediately underhooked it hard and tight.
If your friend had the 1/2 triangle (with legs crossed OR by grabbing
his own ankle) and the underhook on the leg, he would have given his
opponent a much harder time. Could have either swept and finished
the triangle on his side (a la Yves/Hominick) or switched to the armbar
when the guy came around.
however like i said in the video the guy starts his pass and your friend
doesn't really react, or maybe lazily starts to set up his triangle...then
the guy explodes and passes. sorry if i'm misinterpreting the video but
that's what it looks like to me.
also if he KNEW he couldn't get the triangle, he should have backrolled
immediately.
I'm going to have to agree with what the others said. Your friends biggest problem with the triangle is that his timing was very off.
One of the worst things someone can do is reach back to pass when they are on your knees (and that's what your friends partner did). However as soon has the person reaches back and puts his hand in between your legs that is when you need to slap on the triangle. You need to do it when he is still on his knees.
What your friend did was he went for the triangle once he realized that he was being passed. If you watch the video again. Your friends partner reaches back to pass while on his knees. Your friend doesn't react. His partner then gets up on his feet to continue passing and this is when your friend goes for the triangle, which is the wrong time and it is much harder to get it. When your opponent stands up it is much harder to get your hips up and get proper position because your opponent now has gravity on his side. By your friend not reacting fast enough and letting his partner stand up he made it much harder for himself. In your friends partners case it is much safer for him if he reached back initially while he was standing. If watch the video again you should see what I am talking about.
So a couple things your friend needs to work on is:
Clean up the triangle's timing and technique a bit.
Try his best to get on top and not work the bottome when he is outweighed by 100lbs. Trust me I'm 140 lbs. and when someone is 30 lbs. or more over me I work to always get on top. It makes your life much easier.
I don't necessarily expect to get a triangle on a bigger opponent. I might try it, maybe it actually works, maybe it sets up something else, but triangling a big guy is often not the best idea in the world.
Head control is primary for me. If his head and right arm are in your
triangle, he needs to be able to look to the right in order to shuck your
leg by and pass. Pull his head down and to YOUR right, glueing his left
ear to the inside of your right hamstring. If you do this early, it will be
almost impossible for him to shuck your leg by without cranking his own
neck.
This being said, sometimes your timing is off and you miss it. I would
work a lot on guard recovery and retention from this position, rolling to
quarters and then coming back to guard, etc. I use my shin in his armpit
a lot to recover guard or even sweep him when this happens. I'll try to
post details later.