I've used 2 sunblocks that only have zinc oxide as active ingredient: Dermatone and Neutrogena.

The Neutrogena pretty much sucked. I have 2 or 3 bottles of it. The zinc doesn't expire, so I keep it for emergencies. Hopefully the newer formulations work better.

The Dermatone (Z-cote) is pretty good. Not waterproof or sweatproof, but pretty good. I keep it in the car, and can put it over my usual sunscreen (because it's inert) if I'm worried my Banana Boat or Hawaiian Tropic is wearing off. (BB and HT kids stuff have titanium and zinc sunblocks. And the sunscreens that don't wash off because they bond chemically to your skin)

My skin doc said he didn't care what I used, as long as it was spf 30.

I tend more to big hats and long sleeves/long pants. Not so good on the bike, though.