Maintenance will differ depending on where you live and whether you use your bike on the street or in the garage.
Indoors or Outdoors
Waxing your bike (use bike-specific products, or Lemon Pledge, car wax, or Pam), including exposed cables, spokes, and nipples, and greasing the cables under the bottom bracket and inside the cable housings, will do a great job of protecting it. So will removing every bolt on the bike, greasing it and its nut, and retightening it to its specified torque.
Visually inspect tires frequently. Use a chain gauge to check chain wear every month or so. Replace as needed.
Just as you clean the road grime off your body and bundle up inside after a ride in cold slop, your bike’s health will be improved when kept clean and stored in a dry place. A good cleaning setup may require creativity if you have no yard or garage, or your exterior spigots are frozen; a bucket with warm, soapy water over a floor drain is ideal. Remove your seatpost and leave the bike upside down overnight after riding in rain without fenders.
Fenders save your back and feet as well as those riding behind you, but they also prevent water and contaminants from blasting into your seat tube, pedals, bottom bracket, and headset. Full-coverage fenders are great for rain, while clip-on fenders won’t ice up in sub-zero riding.
After every ride, wipe your chain down and lubricate it with heavier oil than you would use in summer.
Increase tire width and reduce air pressure. Rain tires have siping to guide water away; if conditions include snow, a cyclo-cross file tread with side knobs rolls fast yet holds corners in snow and mud. In ice, studded tires are the ticket. Carry an additional spare inner tube, and expect more chances for flats on messy roads.
Lights are a must; keep them dry overnight and charge them regularly.
Indoors: Wipe It
In addition to waxing and greasing your bike to protect it from sweat for indoor riding, wipe it down after every workout with a towel, especially underneath.
Indoors: Pump It
If your rear wheel stays on when using the trainer, run higher tire pressure than you would on the road. Don’t use your best tire—use something old that you don’t mind wearing down quickly.
Lennard Zinn is a longtime technical contributor for VeloNews, a frame builder, a former U.S. national cycling team rider, and the author of countless bike maintenance books including Zinn and the Art of Triathlon Bikes.