When you're out biking on the open road, it's important that you're wearing the right clothing. There are several reasons for this. If you crash, you want to be properly protected so you don't get a horrible road rash (aka have the skin on your arms or legs shredded on the pavement). While most people have an awesome biker jacket covered in patches that looks incredible and fits very well, some bikers don't pay as much attention to their pants. They figure since they can't really decorate them so that they look different, it doesn't matter what they wear. However, that's definitely not true.
One thing you don't want to wear while biking is shorts. Sure, it's very tempting during the hot summer months. It's so warm out, and you're just going to ride down to the store to grab something to drink, so what's the harm in wearing shorts? However, all it takes is one crash to shred your legs and leave you in pain. Even if you just lay your bike over and don't skid across the road, you're still going to get hurt.
Jeans or other regular pants are okay in a pinch, but even they won't hold up very well in the case of a crash. Slacks, in fact, may be shredded upon impact. Jeans will hold up a little bit better, and you can usually wear them, especially ones that are fairly thick, for riding.
If you're going long distance or want to really look the biker part, you should get a good, sturdy pair of leather pants or leather chaps. Leather is very flexible and durable, and it will protect your legs in the event of a wreck. Leather pants, though, can be very expensive and somewhat uncomfortable, so you may want to wear durable jeans for quick trips.
