As a commuter I have no choice but ride in rain from time to time.
- I have fenders.
- I don’t ride in heavy downpours.
- I don’t leave the bike sitting out in the rain any more than absolutely necessary.
- When I get home I hang the bike upside down; sometimes I get some water out. I’ll sometimes remove the seatpost to help ventilate the moisture out of the frame.
- If I feel like it might be damp I later bake the bike, with seatpost out, in the sun.
I’m sure it would be better if they didn’t get wet, but I haven’t had any corrosion related failures on my steel bikes in 15 years in inland south Texas.
YMMV.