However, I would think that if someone is going on a tiyul or bike riding or horseback riding, etc, and she is wearing pants under her skirt, it is okay if her skirts goes above her knees. But again, that is my own assumption, so I may be wrong.
I’m looking for a source one way or the other. Also, if it is OK for a Tiyul, it is probably acceptable for the street as well (as far as the Halacha is concerned).
Thanks