Nun's habit doesn't seem like the best choice when riding a bike.

Looks like a step-through frame which should be a pretty weighty bike frame in itself, but can ease access to women that wear skirts (all honesty, I've yet to see a gal ride this bike frame wearing a dress or skirt) or in this case, the long habit.

I'm not entirely sure if the brakes on this thing are coasters aka "pedal backwards to brake" instead of the traditional hand brakes so she's kinda safe in that regard

This resonates with me. I didn't learn how to ride until I was well into my teens.