Gracie Barra Bristol, (BJJ), Can Sönmez, Bristol, UK - 17/05/2012
The next step is to put your foot on their same side hip (or the floor, depending on your preference) and shrimp out slightly, to make space to insert your knee. Slide that knee over, once again to that same side, until your shin is across their stomach. Hook your instep around their other side. Another option is to angle your knee towards their shoulder, which can act as an entry into the triangle.
A key detail is to then raise your elbows towards your head, so that you're pulling them onto your shin. The aim is to load them onto your leg, which in turn means that their weight is no longer on their legs. Extending your torso back, rather than remaining curled up, may help that weight transfer.
This should make them lighter: drop your other leg to the mat, chopping underneath them as you bring your hooking leg over, rolling into mount. Ryron has two handy tips here. Firstly, use the heel of your hooking foot to swivel and clamp to their side, becoming a leverage point to assist your shift into mount. Secondly, bring the elbow of your sleeve gripping arm further backwards, to put your opponent even more off balance.
If for some reason you're having trouble chopping out their leg, you can switch to a push sweep, which is very similar to the scissor sweep. Everything is the same, except that you don't chop the leg. Instead, move your head back in line with theirs, so your torso is square on, then slide what would have been your chopping leg backwards. You now have room to use the foot of that leg to push into the side of their knee. Tracing a semi-circle, you're then going to shove their knee straight back, which will knock them off balance, whereupon you can roll through to mount as before.
A common mistake is to try and push the knee backwards right away. That is unlikely to work, as there will probably be too much friction. You need to push the knee slightly sideways first, then trace that arc to get the leg back. They should start to fall as soon as you do that, meaning that gravity will help you initiate the sweeping movement.