I was thinking about this again when I was out riding yesterday. Because I also tippy toe, I was seeing what worked for me- I found that if I felt in my mind that I was doing a really exagerrated heel down...I was just about right. If I looked at my feet, they were nowhere near as extreme as I imagined them to be. So even though I may sound like I am overcorrecting, because things are so tight in my lower legs and because I so very badly want to tippy toe, I am turning out about right. When I had this problem horseback riding, I did stretches because part of the problem was that various lower leg muscles were very tight, so that would prob help with biking. Too bad I hate stretching!