The first row of pictures do a good of illustrating how to elongate the spine, avoid letting the head fall into a forward position, and find a neutral position in the low back. The second row or pictures 3-6 remind that the lower ribs are connected to the upper pelvis and this can be tightened up helping to find a more neutral pelvic position. once this neutral position is found and engaged, now activate and tighten the core muscles while using arm movements. These are good core exercises to do prior to biking and to engage once you are on the bike. periodically remind yourself to keep the spine elongated, neutral head and low back positioning, tighten up!