I've had some nodder nagging me years ago on "Why I was not wearing a helmet".
Instead I explained helmets to f-all when a car hits you, that didn't seem to go in. Trying to be nice. It's bad for you. Sarcasm be ready.
Next time I may ask why she's wearing a bit of useless polystyrene that makes cycling look dangerous and gives drivers a stick to beat people who ride bikes with, and distracts from real safety messages and that she should be ashamed...
.