get your hips under their control points and keep the pressure with your hips forward.
The easieast way to explain it is image doing the pelvic thrust to his calves. If you put your head forward you give him easy control of your torso with his grips. Head up, Hips Forward - your all set.
There are a alot of variations when it comes to spider guard. You talking about two feet in the bicep, and double sleave control?
Or Single sleave control, 1 hand on the collar, 1 foot in the hip, 1 foot in the bicep.
I dont agree with these guys at all who are saying not to posture. I Stand & throw my hips in to stop their control points then control the legs and pass. If you try to pass while he has his grips and controls.. thats when your going to be swept. You need to break his grips one way or another or negate his control points.. and the easiest way to do that is get your hips under them.. and get his butt off the ground.
It will releave the pressure of feet in the bicep or hips and then you can put your hands under their legs/feet and dump then over or sprawl to begin a pass.
I dont care if the guy has my sleaves but throwing your hips in makes his feet go out of the bicep or hip control and then you can pass. So only once you take care of his grips/controls from the guard can you lower your head to pass.