The pedals on your bike really serve only one purpose- as a means to transfer power from you to your bicycle. For riding around the block, they don't need to be very fancy...just plastic blocks with grooves or teeth to plant your feet onto. But if you want to go on longer rides (anything over 10 miles), you'll benefit greatly from something better, because:
Without something holding your foot securely to the pedal, it would be easy to slip off the pedal and send your foot into the wheel. Not so likely to happen on a trip around the block, but on a longer ride, when you're tired...
There is a correct placement for the position of your foot over the pedal axle
A good pedal/shoe system has to be able to transfer all of the power from your leg to the pedals without trying to bend your foot over the top of the pedal, which causes both fatigue and pain
You shouldn't have to think about how your feet connect to the bicycle while you're riding. You should be concentrating on having fun, not technique!
In the old days, bike pedals either were plain (with no straps to hold your foot in place) or they had toe clips & straps. The toe clip was usually steel (most are now plastic) and formed a space, or box, at the front side of the pedal that you slid your foot into. Keeping your foot there is the responsibility of either a leather or nylon mesh strap, which you can pull tight when you wanted to make sure your foot stays in place, or loosen so you can get your foot out when you stop.
Toe clips & straps are still the norm for nearly all bikes between $350 and $1000. They're very inexpensive and don't require the use of a special shoe. But when used with conventional shoes, they tend to focus pedal forces onto a small part of the bottom of your foot, creating fatigue & pain on longer rides as your foot tries to bend itself around the pedal. Also, if the straps are not loosened as you come to a stop... Of course, you can always leave the straps loose, but then your feet don't stay in place without conscious effort to keep them on the pedals. And if you've tightened them down, you need to reach down and loosen them prior to stopping (a somewhat risky operation).
It's time to enter the clipless pedal revolution!
With a clipless pedal system, you wear special cycling shoes (but don't let "special" put you off...many look similar to normal hiking or walking shoes!) that allow a "cleat" to be mounted to their sole. This cleat literally snaps into a receptacle on the pedal, allowing you to quickly (and without having to reach down!) connect your shoes to the pedals and take off.
But, of course, you weren't worried about taking off...you're more concerned about stopping without falling over! Well, that's far more easily accomplished with a properly-chosen and adjusted clipless pedal system than it would be with toe clips & straps. With nearly every clipless pedal on the market, all you need to do is pivot your heel outward and you snap right out of the pedals. It's that easy!
What about the shoes? What makes them so special?
A high-quality cycling shoe is designed to be lightweight, comfortable (some optimizing comfort for both riding and walking, while others are made for riding only), and efficient at transferring power from you to your bicycle without pain & fatigue. Popular brands include Nike, Shimano & Sidi (which, not coincidentally, are all lines Chain Reaction carries!), and prices range from $70-$350. Their durability is very good, and the workmanship is generally as good as, and sometimes better than, normal street shoes selling in the same price range.
And the different pedal systems?
There are two basic choices-
Cycling-only pedal/shoe systems, which will have a cleat that mounts below the shoe and is optimized for cycling (and will send you sliding across the freshly-waxed floors at Robert's supermarket in Woodside if you're not careful...just grab for something in the middle of one of those row-end displays on your way down!). These were designed originally for road bikes, and are inappropriate for mountain bikes, where getting off and walking occurs frequently.
The newer systems featuring a cleat that's recessed into the bottom of the shoe, allowing you to walk normally when required. These were initially designed for mountain bikes, but find their way onto more than half of the road bikes we sell as people like the convenience of being able to walk around without slipping or sounding like a tap dancer (which is what exposed cleats sound like on wood or concrete floors).
Why would you want a shoe that has an exposed cleat (making walking around impractical) when you can opt for one that's recessed? Mostly because the shoes will be a bit lighter weight (there's no extra rubber on the bottom of the sole, just a plastic bottom that the cleat mounts onto) and also because, with some systems (LOOK & Speedplay, for example), the interface between the shoe and pedal is larger and gives a more solid feeling while pedaling. However, great strides have been made with the recessed cleat designs, and they are now almost as light and efficient as the non-recessed designs.
What do the pedals cost?
For non-recessed (cycling-only) designs, very high quality pedals start around $80 for a basic LOOK pedal, to $125-$200 for the newer, lighter Shimano SL and Speedplays. All represent excellent choices and offer what's known as a "floating" cleat. This type of cleat is one of the most wonderful things to come along to cycling in years; it allows your foot and knee to determine their own alignment on the pedal, which is extraordinarily important in reducing knee stress and pain. Prior to these designs, an improperly-set cleat could actually cause serious knee injury!
For recessed-cleat designs, there are a number of designs out there, but it's tough to do much better than the basic Shimano SPD. Prices have come way down, with just $50 buying a great pedal (Shimano's M520). These are all dual-sided, meaning that you can step in from either the top or bottom, and, while originally designed for mountain bikes, are equally at home on road bikes. They also have rotational float, which makes them much easier on the knees than earlier designs.
Great deals that aren't. There are many other recessed-cleat pedals, but we generally don't recommend them because, in our experience, they are frequently far more difficult to get into and out of (Onza and Tioga are great examples from the past) and difficult to find cleats for due to continuous running changes in their designs. We've also seen some copycat Shimano-like pedals made for a major mailorder company. At first inspection they look pretty nice, but they interface very poorly with shoes. Check it out...a recessed-cleat pedal/shoe design requires that the shoe be supported at the outside edges of the pedal to keep from flopping around. But on these pedals and many shoes we've tried, the sole of the shoe sits well above the pedal, so the only thing supporting your foot is the tiny cleat itself. This is not enough for proper support; you get an uncomfortable, excessively-wobbly feel while pedaling. And they're not even that cheap, at $40/pair...sure, it's maybe $10 less than some others, but it's a bad place to save a small amount of money.
Proper cleat placement is important, even though the new floating-cleat designs have made it far less critical. There are basically two things to set up- approximate cleat angle and fore/aft positioning.
For the angle, we generally set up the cleats so that, when the shoe is moved inwards, your ankle won't quite hit the crank. With this position, all the pedal systems we offer allow a significant outward angle from neutral (in line with the bike), meaning that your foot can go just about anyplace it wants to. The only reason for changing the cleat position so it allows less outward movement is for those who have difficulty moving their heels out far enough to exit the pedals.
For fore/aft, we start by positioning the cleat so the ball of your foot is centered over the pedal. This position generally results in high energy transfer from foot-to-pedal without undue stress on the knee. However, for those who've experienced knee problems, the first thing that should be tried is to move the cleat towards the back of the shoe, dramatically reducing the amount of leverage that the pedal can exert against your foot and knee.
But will I fall over?
OK, we'll finally answer the BIG question. Once you get used to clipless pedals, the chances of coming to a stop before exiting your pedal (and thus falling over) are greatly reduced. BUT...chances are, in that first day or two, you'll forget that you need to twist your foot to the side (instead of pulling back) to get out. By the time you recognize your mistake, it's too late, as you've lost all forward speed. And, with no place to go but down...you get the picture. You will, in very slow motion, and nearly always with people around to see it happen, fall over. You're not likely to get hurt, but it's terribly embarrassing. And most likely there's nothing that makes you so special that you'll avoid the fate shared by just about everyone else. Just try and remember this...
It's almost impossible to come up with a truly original way to embarrass yourself on a bike. The rest of us have already, as they say, been there, done that.
(dikutip dari http://www.chainreaction.com/pedalfaq.htm)