Modesty is not relative, but it is very situational.
A bikini in church is very immodest. A regular biking on a beach full of women in string bikinis could be quite modest.
(I have a similar problem to you as to going shirtless. I try to never go shirtless on the beach as people keep trying to roll me back into the ocean!)
“I try to never go shirtless on the beach as people keep trying to roll me back into the ocean”
Luxury. In my day, they used to harpoon us—if we were lucky.