Mountain biking has exploded into an array of genres and cultures. Frame geometry, wheels sizes, suspension, gear ratios – the list goes on, and pedals are no different. So, how do you know what's right for you?
For mountain biking there are three kinds of pedals you'll see on the trail: clipless, platform and a combination of the two.
Platform pedals: just what they sound like: big, flat platform, sometimes called flatbeds, which provide a stable plane for your foot placement. Many bikes come stock with platforms, they're great for commuting or errands and more often these days, you'll see them on the trail. This design is also popular with the downhilling and dirt jumping crowd because of their easy on and off nature.
Clipless pedals: coined SPDs after the company that invented them, the name clipless comes from pedals mounted with plastic cages – toe clips –to hold a rider's shoe. Clipless pedals have small, spring loaded vices – think tiny ski bindings – that clamp around special cleats mounted on the bottoms of SPD specific shoes. There are a few designs out there and they all perform the same job.
Clipless pedals offer a union between bike and rider. Instead of two points of connection – your two hands and the handle bars – now you have four, with your feet securely “clipped in” to your pedals. You can adjust tension and amount of play, called float.
While there is a learning curve, engaging the pedals becomes second nature. Riding clipped in inspires confidence and increases pedaling efficiency. Called “pedaling in circles,” it allows riders to pull their pedals up around the second half of the rotation instead of just pushing them down the first half. This increases the transfer of energy to the wheels – It's kind of like putting your bike in four-wheel drive.
SPD/platform combo: clipless on one side and a platform on the other. Riders can use the platform for pedaling troublesome terrain and then flip and clip in when things smooth out. They're also convenient for riders who mix up their riding styles.
So, there it is. Look around and see for yourself what riders are clipping, or not clipping into. There's something for everybody, so find what's right for you, and pedal away.