From the 1986 Instructor's Seminar in Berkley, CA, T.K. Chiba shihan details the four stages of Iriminage:
1) Entering (Irimi)
2) Turning (Tenkan)
3) Spiraling
4) Entering across the line
Important points:
a) Jodan, Chudan Gedan variations (Chudan is basic)
b) Keep hold of uke's collar, use it to help break uke's balance backwards.
I believe this video contains the absolute essence of Chiba sensei's aikido. Watch his body positioning and how he moves to uke's blind spot. Watch how he bends his knees and gets under uke's center. He throws by taking uke's center with his (Chiba's) body. The movement of his arms, while powerful in and of itself, is secondary to his hip rotation. His timing is impeccable... he cuts uke down and adds his own force to that of uke as uke scrambles to regain his balance. There is so much to see in this video, if the viewer has the eyes to see it.
