When buying a SRAM crankset, it’s important to know what interface it uses. The interface refers to how the drive-side (right) crank arm attaches to the spider or direct mount chainring. SRAM makes both 3-bolt and 8-bolt cranksets. Both of these interfaces use Torx 20 bolts, however the shape of the interface and the number of bolts varies.
SRAM 3-Bolt Interface
SRAM 3-Bolt Interface cranksets, pictured below, use 3 Torx 20 bolts to secure the spider or direct mount chainring to the crank arm. While SRAM still makes these cranksets, it’s an older style that has largely been replaced with the 8-bolt. Currently, only a few road and MTB cranks are being made with this interface.
SRAM 8-Bolt Interface
In a SRAM 8-Bolt Interface, pictured below, 8 Torx 20 bolts are used to secure the drive-side crank arm. This is the interface used on most SRAM road and MTB cranksets including all power meter spiders and cranks.
In the event you need to replace chainrings, crank arms or would like to upgrade to a SRAM or Quarq power meter, knowing what interface your crankset uses will help ensure you get the correct new part!