How Much Do Unlined Climbing Shoes Stretch?

How Much Do Unlined Climbing Shoes Stretch? Shoes have three different types of uppers, all of which stretch differently. Unlined (leather and suede) uppers can stretch up to a full size. Lined uppers only stretch about 1⁄2 a size. Synthetic uppers may become slightly softer over time and “break-in”; however, they will stretch very little,