Bike maintenance is especially important if you ride in the winter. While the colder temperatures themselves aren't really much of an issue for our equipment the salt and sand that gets dumped all over our streets certainly is. All of that crud finds its way onto our drivetrains and braking surfaces and, if not monitored diligently, can lead to very premature wear.
That's the bad news. The good news is that with a little on-going maintenance your bike should remain almost trouble free throughout the winter and also avoid most premature aging. The first step is to regularly clean your bike after messy rides, especially focusing on the drive train and breaking surfaces, but along with that you'll want to make minor breaking and shifting adjustments. It doesn't take much grime to detrimentally affect your shifting and breaking, and once that happens your components are much more likely to wear quickly, so after every cleaning it's good to do a quick check and make a few minor adjustments as necessary.
The Big Blue Book of Bicycle Repair has been a sort of bike repair bible for years, and it's finally received its first update. We now have in stock the 2nd edition for just $26, and trust us, it will pay for itself quickly. If you're inclined to do minor adjustments and repair yourself but don't have all the know-how this book is invaluable.