i went out for a 60k ride yesterday and forgot to wear sunscreen bad mistake.
So word to all riders pack sunscreen and apply b4 starting the ride. Im sure all of us will be wearing cycling jerseys so you want to protect your arms legs neck and face.
I carry a can of the Neutrogena spray-on stuff. Quick and easy. It has the added benefit of not getting my hands all slippery... which can be fun now and then but not while riding a bike.
Just watch for some types - some sunscreens can get into your eyes when you sweat. It's not too great at the best of times, but worse if you have contacts!
When cycling I don't apply sunscreen on my forehead or close to the eyes. I find the helmet and wrap-around sunglasses provide adequate coverage. If you're bald you may want to consider a bandana or other head cover. My brother had tan lines to match his helmet vents after last year's ride.