Most dedicated cyclists are aware that there are two standards for mounting cleats to the soles of cycling shoes – face facts: if you don’t know what “cleats” are, you probably aren’t a dedicated cyclist. All snarkiness aside, the Look® standard attaches with three bolts in an equilateral triangle and the Shimano SPD® (SPD stands for Shimano Pedaling Dynamics) standard attaches with two bolts in a line. Some shoes accept both styles, some accept only one (usually Look). Cleats from other manufacturers, like Crank Brothers and Time, are compatible with one standard or the other – as a general rule (but not hard and fast), SPD cleats are used with MTB shoe/pedal combinations and Look cleats are found on road bikes.