gravel in the wet
Let’s be honest
Let's be honest, wet gravel roads can be a little messy. After all, gravel roads are made of gravel and - dirt! Water runs off a paved road pretty quickly but gravel roads can take a day or so to dry out, especially after a few days of rain. So the first rule of riding in the wet is: be ready to get a little dirty. But HOW dirty you get has to do with how how messy the road is, but also fast you're riding, how well you set up your line down a gravel road, and your bike handling skills.
First Things First
First things first, wet gravel roads are usually more slippery than wet paved roads. Those corners you can take no problem in dry weather become a skating rink in the wet. On gravel - and especially wet gravel - keeping your tires vertical underneath you is safest. Don't lean into corners unless you're really confident of handling your bike. No leaning and no hard turning, which also means seeing farther ahead than you might usually so you can choose your line around muddy holes and wet grass with a minimum of quick steering.
Rut to Rut
The one exception for quick steering is if you need to switch from one side of a gravel road to the other. Car tires usually build up a rut where they go. Usually this is the best place to ride, but if you need to switch from one rut to another, your bike tire will manage going over a rut best if you ride square to it. In this case, a quick twist of the handlebars in the direction of the rut you want to cross and then straightening out - while leaning slightly to the other side - should do the trick; a little practice should make this a simple task.
More Ideas
Adjust your speed accordingly. Steady progress gives you the best advantage, with your weight centered more over the rear wheel while you're seated in the saddle. This gives your drive wheel traction so you can keep moving through any muck. Trying to blast through a muddy section in hopes of getting through it fast is a recipe for landing on your bottom.
There is no shame in deciding that the gravel road you picked is too wet and muddy to ride - after all, there's probably another one nearby! - and no shame at all in deciding to wait for a drier day. The point of gravel riding is to have fun and make it your own. But if you're curious, or want to improve your skills, gravel roads are usually quieter and freer of car traffic than paved roads, and mud and gravel usually have a lot more give than asphalt if you find yourself in over your head. No one starts out being good at it.
You can think of what it must have been like in Portland a hundred years ago, when almost all the roads were dirt and, if you were lucky, a little gravel. How did people get around then? You're about to find out....