Just popped this on Insane Hills level "Born to fly". Number 6 in the first set of levels.
* You will get the Niinja Performer achievement with this method.
You can keep a combo going for the first 5 jumps. Making sure to nose or tail grab. (holding the grab as long as possible) whilst doing as many rotations(back/front flips) as you can. Land on the rail after the fourth jump and you should have enough score to pop achievement(s) after you trick the 5th jump.
You should have a score of 1000+ with a multiplier of 9+
Note: The distance between the first and second jump is the longest. Hold your grab until you nearly hit the ground to keep your combo going into jump two.
There is no need to flick jump any of the jumps.
I landed and banked the combo - Not sure if that is a requirement or not. Best to land it just in case.