What are they?
SPD refers to a type of clip-in pedal system. Clip-in pedals are traditionally known as clipless pedals. Clip-in pedals are used with cycling shoes that have cleats attached to their soles.
You clip the cleat into the pedal so that your shoe is connected to the pedal while you’re pedaling. The SPD cleat attaches to your shoe using two bolts. (Another type of pedal system called SPD-SL uses three bolts).
These pedals have to be used with SPD cleat compatible shoes installed with SPD cleats. Most mountain bike, urban, and indoor cycling pedals use SPD clip-in pedals.
What are their benefits?
The cleat used for SPD clip-in pedals is smaller than the cleats used with SPD-SL clip-in pedals. The cleat is also recessed, meaning it sits flush with the sole of your shoe. Both these features make walking easier. It also protects the cleat from wear and tear.
On the bike you’ll instantly notice the benefits of clipping into your pedals. You’ll likely be able to pedal with a higher cadence, improved power transfer, and better efficiency. It’ll also feel more stable - by securely connecting your foot in the correct position on the pedal, you will be able to pedal harder and faster without fear of your foot slipping off the pedal.
Clipping in can also change your pedal stroke and the muscles used. The secure connection allows you to push down through the first half of your stroke and pull up through the second, accessing both your quads and your hamstrings.
How do you use them?
If you are new to clipping into your pedals, you may want to practice on a stationary bike or in an open parking lot to get the hang of the motion before hitting the open road or trail. With some practice, clipping in and out of the pedals will become easier and easier until it becomes second nature.
Start by flipping the pedal over to the clip-in compatible side (if they have a flat pedal or cages on the other side). Position your foot so that the cleat lines up with the clip on the pedal and push down and slightly forward. You will hear a satisfying click as your foot secures into place. To release your foot from the pedal, turn your heel away from your bike to disengage.