Loosened a knot on her panties.

Not a lot, but just that extra inch or two to make them slide down off her hip. Alex not being accustomed to thongs in the first place was very aware of this shift and wiggled her butt a bit while standing on the peddles to try and get it to work itself back into place.

With the only result being that the center line of the thong worked itself off her slit and out of her crack to lay uselessly to the side.

Resolving to fix them at school; She was just congratulating herself for thinking ahead and including her bloomers as part of her outfit (having yet to realize that she's forgotten them at home in her rush). When she felt the otherside slip as well. Her panties were now still tied around her legs but with each trust of her legs to peddle the bike they began to slip further down until they were eventually just resting on the seat of the bike. Several Cafe patrons enjoyed the view as Alex stood up on her bike and leaned low into the turn to cut through a college campus a few blocks from her school.

Alex took a moment to appreciate the large center fountain leaning over to smell the flower arrangement while still straddling her bike.

She realized she was getting a lot of funny looks from the flow of students making their way to their 8am classes. But wrote it off as being in a tartan skirt and pigtails in the middle of campus. She had a self satisfied smirk to herself as she rode off towards her school.