It should be the first thing you think about before biking: the most important sports apparel you need for biking is a well-fitted helmet. Even for casual riding, your bike helmet protects you against the less-than-alert car drivers on the road, and for the other people and objects that may distract you and cause you to lose your balance. A bike helmet should sit low on your forehead and should not wobble. Ideally, purchase a helmet at a store that sells sports apparel and accessories and find a knowledgeable salesperson to help you try on a helmet or two to get the right fit. Although bike helmets are adjustable and essentially unisex, if you have a small head, seek out a helmet that is specifically labeled as a women's model and you are more likely to get the snug fit that you need.