Geometry on the bus

I gather "manspreading" is the offense of sitting wider than a woman would. I assume this is related to the widespread practice of "purse-flopping," in which a purse or backpack is used to reserve the adjacent seat.

I remember how weirded-out one youth got when I squeezed into the remainder of the seat beside him, and how flabbergasted the young lady and her friends were when I dropped her purse into her lap. (I had a sore knee and wasn't going to stand if I didn't have to, and she didn't take a hint.) Some folks just want extra space, and devil take the latecomers. The sideways sleepers are worse.

OTOH, there's a bit of geometry and physics involved. Seat heights suitable for the average leave those of us with longer tibia and fibula a choice between sitting straight with the femurs uncomfortably unsupported, crossing the ankles, or spreading the knees sideways. Or cross your legs--and that takes up even more space. It turns out men tend to be taller than women, and have to use a bit more sideways distance to get the hypotenuse to fit. Such is geometry.

When the seats face the aisle, there the stop/start of the bus brings some physics into play. Men usually have a higher center of mass than women, and without some extra torque will tend to flop sideways in a sudden stop. Crossed ankles reduce the lever arm against the seat, and thus the available torque. Unless your seatmates like having people fall on them, crossed ankles isn't the best choice.

Which leaves "spreading the knees out a bit" as the best option. At least until everyone is packed in like parka-ed sardines. Then you have to all sort-of rotate on the seat--everybody with the right shoulder forward and the left back, or stagger sitting at the forward edge and at the back of the seat.

No doubt this is all "so 2017," but the bus ride brought it to mind.