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Buy some grease designed for cold and wet conditions.
Headset? Grease the inner races and under/around dust covers.
BB? Grease the inner races and under/around dust covers.
Pedals? Grease spindles.
Crankset? Grease splines and spindle.
Stem bolts? Guess what. Grease those.
Seatpost? Grease if you are poor. Fiber Grip if you have a job.
Chain? Cheap lube since you will be washing it after every ride.
Housing end caps? Guess what. Grease those.
Di2 junction box in your bar end? Just cover that in a thick layer of grease.
Hubs? Guess what.
Freehub body? Grease the seam at the base of the splines / threads (if you have a freewheel) Do not grease ratcheting mechanism.
Cleats? Grease those.
Once everything is greased you can wash the bike as needed by using a hose attachment to gently mist everything. Do not spray around the BB of hubs.
If you are poor and you bike(s) cost under 1,000 United States Dollars or ride just once a week, you can let it rust in your garage or outside. Just let that shit rust into the absolute trash that it is. You don't deserve nice things.