So, if you've been following my recent posts, we've got a little themed section going on about bike commuting, and I thought I'd provide a series of tutorials on how to accessorize your bike on the cheap. Today, the ubiquitous bike basket.
First of all, determine where you want the basket: front, back, or both. If your decide to go with a front basket, make sure to leave enough room so that your brake cords aren't cramped--this can lead to trouble. It's also best to only carry light items in front baskets, as heavy things can make it difficult to steer.
Front baskets: The best baskets for your handlebars are lightweight ones: wire or the traditional woven sort. You don't need to buy an expensive one made especially for bikes; anything with at least one fairly flat side will do. I've even seen repurposed (wicker) bathroom trashcans. You can attach the basket easily by tying the handles or the top edge to your handlebars with a sturdy ribbon, but for more stability, I recommend zip ties. The more you add, the more sturdy your basket will be, and the less pressure each holding point will be supporting. Again, be sure to position your basket so that pressure is not exerted on the brake cables.
Rear baskets: For these, you'll first need to acquire a rear carrier. Check Craigslist for cheap used ones, but make sure they come with all the hardware you'll need to attach it. You have more choices here as far as what kind of baskets you can use. You can still go with woven or wire, but you can also use less traditional bike baskets. I use a plastic milk crate, but you can use pretty much any container that's not solid (so you have holes through which to thread your zip ties). Take a look around the house; you're bound to have some sort of plastic organizer or something that you could use.
Keep in mind that you don't want the basket to be terribly wide because then your mobility will be impaired (i.e. you won't be able to fit between parked cars or through other tight spaces. Also, if you mount and dismount your bike by swinging your leg over the seat (like most people do), you'll need to make sure your basket isn't going to be too high for you to be able to do that comfortably.
To attach the basket, zip ties are your best bet; they hold really well, they're weather proof, and they're lighter than metal hardware. Make sure you used enough ties in various places that your basket can't move at all. Even a little play can be dangerous as it causes repeated stress to the ties.
Holding it all in
If you have an overflowing basket and you're worried about your stuff falling out, bungee cords are a quick, easy way to secure your stuff. Just stretch a cord or two from your handlebars or rear carrier, up and over your basket. If you're carrying smaller items, use your jacket or an old piece of cloth/plastic, etc. to drape across the top and then pull the bungee cords over that.
The worst thing is to arrive home with a wet basket full of soaked stuff, so if it rains much in your area and you're concerned about getting caught in it, rain proof your basket. You could just drape an old poncho over everything and tuck it in, but for a more stable and permanent solution, you might consider an attached cover. You could fashion a hard lid with some small hinges, but for something lighter weight, I made a flexible cover with a couple old shoelaces and plastic grocery bags. Use some wax paper and an iron to fuse several layers of grocery bag plastic (tutorials here and here) into a sheet large enough to cover the top of your basket, fold the side edges over about an inch and fuse again (for durability), and cut small slits through which to string the shoelaces. Then tie one side of the cover to the side of your basket (tight knots--you won't be untying them), and you're set. Drape the plastic over the basket to find a good fit, and fold over and sew the hinge-side corners so they lay nicely. Secure closed by tying the other shoestrings (loose knots or a bow tie) to the handle area on the other side.
Alternatives to the shoestrings include snaps or buckles (recycled from an old woven belt or the straps of a backpack. These you'll have to sew on, so they'll require a bit more time, but they're more durable than the shoestrings and make for quicker attaching and detaching. For the side that remains attached to the basket, you could use keychain O rings in place of the shoestrings for more durability and ease of movement. Note that woven/wicker baskets themselves aren't very weather proof. They could even mold eventually.
Here's mine. It uses shoestring on the hinge side and a piece of an old belt on the closing side. If I had it to do over, I'd use O rings instead of shoestrings.