What to Wear?
Figure 1. This short League of American Bicyclists video provides some tips about what to wear when bike commuting.
People thinking about getting "serious" about biking sometimes start by buying a bunch of specialized bike clothes. Or, worse yet, are discouraged from riding because of all of the stuff they think they have to buy. Take a deep breath and put away that credit card.
Buy One Thing First
If you don't own a helmet that is less than two years old and has never been in an accident, buy one. They start at around $20.
That is the only "must have" cycling-specific equipment you need.
Ride and See What You Need/Want
Rather than considering the purchase of additional, bike-specific clothes as a riding prerequisite, ride! Just put on your helmet, get on your bike, and ride. Repeatedly. If you never encounter any problems or discomfort, you're good! You have everything you need. If you do encounter problems/discomfort, some additional items may be helpful:
1) Safety Vest: Consider a safety vest to increase your visibility. They cost less than $5, can be worn over the heaviest of jackets or the lightest clothes, and can help you be seen by drivers.
Other than that, start riding regularly and see what you need/want:
2) Layer: Especially in the winter, it is easy to be too cold at the beginning of a ride and too warm in the middle of a ride. If that is a problem for you, the solution may be to layer so that you can add and remove clothes to stay comfortable. You may already have all of the clothes you'll need to do this.
3) Change of Clothes: Are you riding to work? You might want to have deodorant and a change of clothes when you get there. Or the distance/speed you ride to work may make that unnecessary. Try it and see.
4) Right Leg: Are you wearing long pants (typically more of a bike commuter issue)? Are they getting caught in your chain and getting torn or greasy? You can roll up your pantleg, pull your sock over your pant leg, or invest in a leg strap. They cost around $5 and are often reflective, increasing your visibility to motorists.
5) Bike Shorts: Is your butt getting sore? Your body will adapt as you ride more; give it time. If you are still experiencing soreness after 10-20 rides, especially if you are riding longer distances (>25 miles or so), you might want to consider bike-specific shorts or pants. They are padded which can help with your discomfort. They start at about $20/pair.
6) Bike Jerseys: Are you bothered by torso sweat? Steer away from cotton and consider a technical material. A "running shirt" will help to wick away moisture and starts at around $15. You can also get a bike jersey which has the advantage of having pockets on the lower back. They start at around $30 but can be $80+.
7) Bike Gloves: Are your fingers getting numb or tingly? There are several potential solutions to this, one is to invest in some bike gloves. The padding in bike gloves is designed to distribute the pressure that is causing the numbness. They start at around $15.
The important take-away here is that you may not need all of this stuff, and you certainly don't need all of this stuff before you start your bicycling habit.