Sandyford is a bit closer to 3-Rock than Stillorgan but there's not much in it! If you're planning on cycling from home somewhere around Stepaside would be ideal and there are plenty of nice new estates and apartment complexes in the area ....... and if you need any one to help you move!!!
to cycle out from D6 area it takes approx 25-30min to Lamb doyles and 50min to Leadmines. Anywhere south of Rathfarnham will be really close to most of the trails, 10-15min cycle.