"Since I'm riding my bike to work now does that mean I have to start wearing those shoes that clap really loud on the pavement, start wearing tight fitting clothing, cruising the internet for anything biking related and become a Lance Armstrong fan??"
Well, you may get some hard core racers who will tell you that but a simple bike commute to your place of business doesn't "require" all of that. The main thing you want to consider is comfort. Let's consider a few articles of clothing:
1 - Shoes - Bicycle specific shoes are desirable as they have harder soles that don't flex as much as your sneakers or shoes you walk in. They help transfer more of your energy into the pedal and minimize wasted energy. There are however a wide assortment of cycling pedals and shoes that are comfortable to walk in when not on the bike so all is not lost. But, a pair of your comfortable sneakers will work just fine as well.
2 - Pants - Cycling specific shorts are form fitting and come with padding called "chamois" that helps reduce the chaffing between your thighs. There are cycling commuter shorts or knickers you can buy that look just like regular shorts but come with chamois sewn on the inside. You will find these rather comfortable on the bike and off the bike. But, don't let that stop you from wearing a regular pair of comfortable shorts. If you do wear long pants don't forget to strap something around your right pant leg so it does not get stuck in your chain!
3 - Shirt - Cycling jerseys are form fitting, breathable and come with nifty pockets on the back to store things. Commuter jerseys are more of a relaxed fit but still breathable and may come with pockets in the back or side. You'll find that commuter jerseys look almost like any shirt you might wear to relax in. Again, this is based on preference but you could wear your favorite non-cycling related shirt as well. Just be aware that cycling specific shirts are longer in the back so when you are bent over on the bike you won't have a "bare" spot bearing for all to see.
4 - Gloves - What's the deal with gloves that don't have fingers? Well, cycling gloves have padding that help absorb the shock from bumps in the road or trail. Also, did your mother ever tell you not to wipe your nose on your sleeve? Well, she never mentioned anything about gloves! Let's face it sometimes when riding in the cold your nose well get a little runny. Better to wipe on your gloves then your bare hand.
5 - Sunglasses - Do you wear sunglasses while walking outside on a bright sunny day? Then you'll appreciate a good pair of cycling shades as well. Their purpose is to keep out ultraviolet rays so you can see better but also to protect your eyes from the wind and debris that flies around the air while riding. Make sure you get a pair that wraps around enough so the wind doesn't come in through the side. Are these necessary? No. . . but they do look cool! And uh. . . are functional as well!
6 - Helmet - "My hair will get flat if I where a helmet!" You'll likely hear different opinions on the use of helmets but one thing is for sure is that wearing a helmet will protect your head and could save your life in the event you ever crash. So, why take chances? Plus, they help make you more visible if you have a colorful one. Now, what to do about your hair. This is one area where you may want to consider a new look. Shorter hair styles don't need to be maintained as much and don't lend themselves to "helmet hair". However, there are many bicycle commuters who have long, flowing, curly hair and have learned a few tricks. You can tie your hair up into a pony tail and let it go out through one of the air vents of your helmet. Or you might consider pinning the top of your hair. With all the hair gels and styling cremes we have today you can certainly get your hair stylin again when you get to the office if you need it.
Do you remember having to wear all this stuff when you were a kid riding your bike? Probably not. So, don't let that stop you now (with the exception of a helmet). Just know that there are more comfortable and functional cycling clothing out there should you decide your current wardrobe isn't cutting it.