How Are They Safer And More Efficient Than Other Pedals?
These style pedals work in conjunction with cycling shoes. The combination of the pedals, and the shoes with cleats bolted on to their soles, allows you to "click" in and out without straps. Clipless pedals are safer because they lock your foot to the pedal with a spring retention system that you can disengage from by twisting your heel outward (and sometimes inward also). By locking your foot to the pedals, you have less chance of a foot slipping off of a pedal and onto the pavement while you are riding. Being able to release your foot without reaching down to undo a strap, you increase your chances of putting a foot down quickly when needed and you increase your chances of getting free and clear of you bike in an emergency situation.
Clipless pedals can add up to 20% more pedal efficiency by rounding out the pedal stroke. You are able to lift your leg at the bottom of the pedal stroke and increase the power to the pedals. Also, the lack of a tight strap across the ball of your foot that cuts off blood circulation (associated with clips and straps) adds to your riding comfort and thus adds to your efficiency.
Road Clipless Pedals In General
Road clipless pedals are made narrow to save weight and allow for greater cornering clearance. Most road pedals are made with a retention system on one side of the pedal to further the weight savings and cornering clearance. Here are some descriptions of some of the more popular road clipless pedal systems.
Here are some descriptions of some of the more popular road pedals.
Shimano SPD road These pedals use the same side by side bolted metal cleats that the mountain bike SPD pedals use. The system is popular with the cyclist who has both a road bike and a mountain bike because shoes and pedals are interchangeable when needed. The SPD cleat is very durable and compact but requires some practice to get used to engagement of the pedal since you need to know exactly where on the bottom of your shoe the small cleat is. This system allows some float (4 to 6 degrees) in you heels to aid against fatigue of your knees, but the amount is not adjustable.
Shimano SPD R
This now obsolete system (currently sought after by track cyclists) is a larger version of the SPD system but uses a fore and aft bolted cleat. Benefits of the SPD R system over the SPD system are that there is a larger contact area with the pedal (preventing hot foot and helping with engagement) and you are able to adjust the cleat on the shoe while it is attached to the pedal (for greater accuracy). These pedals are not interchangeable with regular SPD pedals. Heel float is adjustable from none up to 10 degrees in three increments by changing the cleats.
Shimano SPD SL
This system is another refinement by Shimano. It was rumored to have been designed to help aleviate hot foot on longer rides. It parallels the look style cleat and pedal, with a few refinements, such as better cleat wear and closer shoe to pedal distance. It uses three bolts for attachment to the shoe.
This system uses a three bolted plastic cleat that is large (preventing hot foot and helping with engagement). The cleat has remained unchanged since the late 1980's. The pedals have been refined for lighter weight and easier engagement and tension adjustment over the years. Despite the age of the design this system is still used by many cyclist. The cleats are plastic and need to be replaced more often if you walk frequently in them. You can get cleats for these pedals that have no float or that have 4 degree or 9 degree. Campagnolo and Wellgo make very similar versions of this pedal system.
A recent design that is smaller and lighter than the traditional Look system pedals. It still uses three botls to atach, but the cleat it is not cross compatible with non Keo pedals.
This system uses a two piece cleat that has a total of four bolts. These pedals have 10 degrees of heel rotation and use very little spring tension for engagement and release. Due to the design of the pedals no tension adjustment is necessary. These pedals are popular with people who need to have as little stress as possible on their knees.
These pedals use a four bolted large cleat that has the retention spring in the cleat. The pedal resembles a lollipop. Heel rotation is very generous and very unencumbered. Walking in shoes with these cleats is difficult due to their size.
If you do decide to try clipless pedals you can make for an easier and faster adjustment process by setting up your bike on a wind trainer. This will allow you to get used to the system and also it will let you stop and make small adjustments to the pedals or cleats quickly.