Bow Cam: Compound Bow Cam Types Explained

A bow cam — also called an eccentric — is a rotating, elliptically shaped pulley mounted at the tip of each limb on a compound bow. As you draw the bowstring, the cams rotate and shift the bow's mechanical advantage, reducing the force needed to hold at full draw by 60–80 percent of peak draw weight. That reduction is called let-off, and it is what separates compound bows from recurve bows, which require full holding force throughout the draw.

It is worth noting that the limbs store all the kinetic energy — no energy is stored in the cams or cables themselves. The cam's elliptical profile determines how that energy builds and releases across the draw cycle.

The Four Main Compound Bow Cam Types

Single Cam (Solo Cam)

A single-cam setup pairs a round idler wheel on the top limb with an elliptical power cam on the bottom. Because only one cam drives the system, timing is simpler to maintain. The trade-off is typically slower arrow speeds compared to twin-cam alternatives.

Twin / Dual Cam

The oldest compound bow cam system still in widespread use, twin cams place identical elliptical cams on both limbs, synchronized by a split-yoke cable and a string. When properly timed, dual cams deliver high arrow speeds and a firm back wall.

Hybrid Cam

A hybrid system replaces the idler wheel with a smaller control cam on the top limb. A yoke cable and a control cable link the two cams together. The goal is to combine the easier maintenance of a single cam with speeds closer to a twin-cam bow.

Binary Cam

Binary cams synchronize directly to each other rather than to the limbs, eliminating split yokes entirely. Because neither cam can work independently, this system consistently produces level nock travel throughout the shot cycle.

Why Cam Timing Matters

On any two-cam bow, cam timing — ensuring both cams reach their draw stops in sync — is a critical tuning step. A draw board is the most reliable tool for this check: it lets you slow the draw rate and inspect exactly when each stop hits home. Cams out of sync can produce paper-tuning tears that no rest or nocking-point adjustment will fix.

The right archery cam profile affects draw length, peak weight, let-off, and draw-cycle feel. Pair your cam choice with arrows matched to your draw weight and a bowstring suited to high-performance cam bows to get the most from your setup.