Artemis BJJ (MYGYM Bristol), Can Sönmez, Bristol, UK - 10/07/2015
The tripod and sickle sweeps I taught earlier work well together. There is a third option too, if your partner steps back to avoid those sweeps, putting themself into a sideways-on stance. Although that means they can probably avoid your earlier sweeps, they are now vulnerable to a back take. You can of course also do this technique to start with, if they give you the position, but I normally find it becomes available as a follow up.
This starts off from a de la Riva hook, where you are threading your leg from the outside of theirs to the inside, so that you can wrap your instep by their inner thigh. Be sure to also grab their foot, on the leg you've wrapped. If they're standing sideways, then after securing your de la Riva hook, it should be possible to bring your other leg around behind the same leg you're hooking (kicking your de a Riva hook through to their far hip can help too). Use your second leg to pull yourself around to their back: this is a good application of the warm-up drill where you use your legs to circle around your partner, pushing and pulling yourself around their legs.
If you're holding their sleeve, switch your hand to their belt as you shift your position. This will give you control and it will also provide something you can pull to finish the technique. You could try grabbing their gi, especially if the belt is loose, but the belt is probably the strongest grip as long as they still have it tied. Put both your insteps or shins behind both their knees. From there, kick out your legs and pull on their belt. This should drop them directly into back mount, whereupon you immediately secure your preferred grip with the arms (I'd recommend the seat-belt, which I last taught here).
Teaching Notes: I should note that grabbing the foot is important with the de la Riva hook, as otherwise they can kick their foot free. I doubt this will ever be a lesson I teach all that regularly, but it's good to throw in occasionally, especially as I think it's a handy way to address the problem of them going sideways to avoid the tripod and sickle. Perhaps a good entry lesson to talk about the de la Riva too. That isn't a guard I like as I'm wary of the strain it can put on your knee, but it's an effective guard (and reverse de la Riva seems to be all the rage at the moment).