Maybe I’m a decade behind the rest of the universe, but sunblock towelettes are awesome.
Because they’re moist towelettes in individual packs, they fit perfectly in a jersey pocket or in a waterpack for mid-ride sunblock refresh. You still need help to get the back of your shoulders, but that’s true with any sunblock in my experience.
Sunblock: Still needed in winter. That reflection off the snow will burn you every time.