I used to use a right/rear bar-end shifter to my advantage, before there were any brake/shift levers. I could jump in, say, a 14, stay with even the best jumpers if they were in a 12 or 13, then shift up and jump again, and again, and use my slightly fresher legs to gain speed. I had a chance at beating this one guy who was waaaay better than me in the jump but equal in top speed.

When he got STI I couldn't beat him anymore. I'd always be going the same speed as he was, just 10 feet back.

Standing at high rpm is not that efficient (high to me is over 130-140 rpm). If you can sit at high rpm that's better. Standing is usually better at lower rpms, say under 120.