Water in Frame

There are a lot of areas where water can get into the frame and no frame is 100% waterproof. Around the seat post, down through the head set, etc. To get it out, just hand the bike upside down over night. If your head set and BB have sealed bearings in them, you have nothing to worry about. If they are cup & cone bearings, then you probably should overhaul them sooner than later. Grease is slightly hydroscopic, meaning that it will absorb small amounts of water which can lead to slight corrosion of the bearings and races over time. I believe that your bike has a CF frame. In this case there is nothing that you need to do for it. If it is steel or aluminum, you should spray a little WD-40 or any anti-corrosion spray into all of the tube drain holes after you have let the bike drain. The most likely reason that it did not drain is that your drain holes are clogged, so you will want to make sure that they are all open.

Actually the hanging upside down thing is good, but I would add removing the seat post and angle the bike so that the water will come out the seat tube, and let it hang for 72 hours.

I have steel bikes, my oldest one is 27 years old and has been ridden in many a rain storm and there's no rust in the inside of the bottom bracket which is where rust will start because that's where the water settles. All I do is grease the inside of the seat tube and outside of the seat post lightly with some automotive black grease, then reinsert and wipe off the excess. Then I put grease on the inside of the steerer tube and some to the inside of the wedge (I have quill stems) and coat the wedge, and coat the shaft the wedge is connected to the min. insertion line. This grease helps keep out a lot of water.

But there something else I do. My rear and front flasher come with a rubber gasket that goes on the inside of the bracket for the lights. I've mounted the rear light so that the gasket is tight against the seat tube (light mounted to seat post). Then the front flasher is mounted to the stem and it too has a rubber gasket and it too is tight against the headset. Both of these gaskets serves as an additional layer of prevention for water to get in.

Does all of that work? Something must be working because I don't have rust issues. And before you ask, I've never used a frame treatment on any of my bikes EXCEPT for one and the factory did it when they built it in 07 for me at my request because that was to be my touring bike.