Artemis BJJ (MYGYM Bristol), Can Sönmez, Bristol, UK - 09/09/2015
There are two main methods I use for transitioning from side control to mount. The first method involves reverse scarfhold, where you switch your hips into a scarf hold position to pry their elbow up (you have the option to switch back to a more orthodox side control to trap their arm too). As experienced grapplers will tend to keep their elbows tight, dragging your hip along the floor and into their elbow should enable you to scoop up their arm. However you manage it, getting the near elbow out of the way is key to this particular technique for transitioning to mount.
Having killed the near arm, switch one arm to grip their far arm, putting your other hand by their near hip. Shift your hips right back towards their head, as far as you can. Your elbow will either be in their far armpit or wrapped underneath their far arm for control. This position means you're also blocking their view with your entire body. Lean into them, using your body weight to help maintain control.
That therefore stops them from seeing exactly what you're doing (note that when Saulo shows it on his DVD, he suggests you mess with them by slapping their legs, until you can pick your moment). When you've got up really high and are ready to go (at this point, they should almost be bridging to relieve the pressure), grab their knee to stop them snatching mount, then bring your leg across. Ideally, you'll pin their knee to the mat, squashing both their knees together.
If you're able to clamp their knees onto the near side, there is the possibility of inserting your foot behind their knees and switching through to mount. However, it generally isn't going to be easy to get them into that position, so I wouldn't rely on this, but still, if you can get it that's an easy route to mount. Second, you can grab your own foot and pull it across, or just squeeze it past your own arm, depending on your flexibility. This is useful when you have limited space, but personally I find it feels a little awkward, in that you might tangle yourself up in your own limbs.
Beginners will often try to simply swing their leg over, which is instinctive. However, while that can sometimes work, especially if you time it well, there are two main dangers. The first is that they will snatch half guard as your leg swings over, as it will normally be within range of their own legs. The second is even more dangerous. If they bridge into you midway through your swing, they can roll you onto your back and end up in your guard.
The safest option is to slide your knee across their belt line, then 'fishtail' (slapping the mat with the side of your lower leg) when your knee touches the mat. You can also grab their belt or cup their far hip to stop them shrimping midway through. I feel this is the best method, using steady pressure to get into place, rather than relying on explosive power, flexibility or luck.
A less complicated version is the diagonal slide, which has a lot less steps to it. Start in side control, with a heavy cross face and your other arm under their far arm. Walk your other arm up the mat, until you can get their far arm tight to their head. At this point, you can grab just below their elbow with your cross facing hand, locking their arm to their skull (if you want extra control, you can use your head).
Drive your knee as high as you can on their body, sliding it diagonally over their chest. Aim to put your knee by their elbow. If you go too low, they may be able to snatch half guard. To prevent that, you can also use your free arm to block their legs, either simply shielding the area, or grabbing their near leg and pushing it away. The near leg is the one that will be on top if they try to drag your leg into half guard. If you have control of that top leg, it's impossible for them to get half guard: with just their bottom leg, they can't do much.
Teaching Notes: Last time I taught this lesson, I decided that the reverse scarfhold option was unnecessarily complicated for beginners. The diagonal slide is much simpler, but it does have the downside that people often don't put their knee high enough and therefore get stuck in quarter guard. Still, quarter guard (where they've only managed to trap your foot, not your whole leg) isn't as onerous to pass.
You just bring your trapped knee over to their other side of their body, then complete a knee cut as normal. If you aren't able to bring that knee over, you might be able to do an opposite side half guard pass. If they are turned a lot towards your trapped foot, another possible option is to slide your free knee up high and take their back, rolling over your free knee as normal. Or finally, there is the rolling back take I taught a while ago, though I find that isn't as high percentage.