Very comfortable right from the start and no "breaking in" necessary. Once the SPDs are installed (check security regularly) you can walk on a flat surface without scratching them as the sole takes pride of place in the mount. These are quality shoes that are clearly built to last. I'm glad I made the purchase. NB If it helps I usually wear a size 9 (43€) and sometimes take a size 10 in sneakers. I bought size 9.5 (44 euros).