The only piece on a bike that is almost always touching the rider is the pedal. The pedal transfers the power from the rider’s muscles into the crank arms, drive train, and wheels, motivating the bicycle forward over the ground. Pedals often have a reflector on the front and back to increase the rider’s visibility, too.
So, pedals are pretty important, right?
Before buying a bike, or installing new pedals on your old bike, it’s important to understand the engineering differences between the various pedals that are out there.
Types of Bike Pedals
First, know that there are three basic types of pedals: platform pedals, cage pedals, and clip-in pedals. Each serves a specific purpose.
Let’s start with platform pedals. These are typically constructed of hard, molded plastic or die-cast metal (either steel or aluminum alloy). They’re called platform pedals because the foot rests on top of them–they provide a platform for resistance against downward pressure. They also provide a generous area upon which to place one’s foot. Platform pedals are the most common pedal, coming as standard equipment on most cruisers, mountain bikes, and many entry-level road bikes, too.
Cage pedals (or quill pedals) are constructed of fabricated, turned metal, most often steel, but sometimes aluminum alloy. Cage pedals transfer power in the same way as a platform pedal, but they are equipped to work with additional accessories such as slip-in toe clips or toe straps. These accessories are use to help keep the foot from moving around on the pedal, and to allow the rider to use some upward pressure to transfer power, rather than just downward pressure. Sometimes cage pedals are chosen over platforms because they may weigh less.
Clip-in pedals are pedals intended to be utilized with cleats attached to cycling shoes. The cleat latches into the pedal in a position that provides optimal power transfer around the entire circumference of the pedal-stroke. This is why they are popular with road riders and speed-oriented cyclists. While clip-in pedals can be operated without cycling shoes and cleats, the practice is discouraged due to this type of pedal’s inferiority as a platform, since the un-cleated foot cannot rest flat on it.
One advantage of clip-in pedals is that they hold the rider’s foot in place throughout the entire ride, benefiting the rider’s overall consistency and posture. This can be beneficial for reducing the physiological impact of pedaling on the rider’s knees, ankles, and hips, however getting an accurate clip-in fit is critical to making this benefit possible.
Removing and Installing Pedals
Pedals connect to the crank arms of a bike using a threaded spindle shaft, either 9/16″ or 1/2″ in diameter. Inside the pedal shaft contains the bearings that allow the pedal to turn relative to the crank and remain horizontally oriented as the crank rotates. At the end of each crank arm, a machined thread accepts the threaded shaft of each pedal.
Note that, in order for the pedals not to unscrew while pedaling, the left pedal and crank arm are threaded in reverse. This means turning the left pedal counterclockwise in order to tighten it to the crank arm. When installing or removing pedals, a pedal-wrench is recommended to torque the pedals into the crank arms.
Prior to installation of pedals, you should put a small amount of grease into the thread on the crank arm. This will allow the threads to screw together more smoothly and allow for easier remove of the pedal later on.
When installing pedals, hand-tighten the pedals at first, and be sure they are turning easily into the crank arms. If they are not turning easily, this is an indication that the pedals are cross-threading. Do not proceed further since cross-threading will ruin the crank-arms, pedals, or both. If you encounter this difficulty, carefully back the pedals out of the crank arms and try starting over.
Be sure you have the left pedal on the left crank arm, and the right pedal on the right crank arm, too. All pedals are marked “right” or “left”. Sometimes these designations are abbreviated with “L” and “R” printed or embossed somewhere on the pedal itself–usually on the shaft.