What is the difference between a cam and an idler wheel?

A cam is shaped off-centre, so it changes the leverage through the draw and sets the draw force curve and the let-off. An idler wheel is round and turns around its centre, so it only feeds and takes up string. A single-cam bow has one of each.

Do single-cam bows need cam timing?

Not in the same way as a dual-cam bow, because there is no second cam to keep in time. Single-cam bows still have timing-related adjustments, such as the draw stop, and their nock travel is tuned through the cable and yoke system. Follow the maker's tuning guide.

How do I know if my idler wheel is bad?

Watch for a wheel that wobbles, a grinding or squeaking sound when you draw, a string that rides out of its groove, or tears you cannot tune out. Any of these is worth a check at a pro shop, where a bow press is needed to take the load off the wheel.

Vodicí kladka

An idler wheel is the round wheel on one limb of a single-cam compound bow, paired with a shaped power cam on the other limb. The cam shapes the draw force curve and the let-off; the idler wheel simply turns, feeding string as the bow is drawn and taking it back up when it is released.

Detaily

Compound bows use several cam systems. A single-cam bow has one power cam, usually on the bottom limb, and a round idler wheel on the top limb. Dual-cam, hybrid and binary systems put a cam on both limbs instead. Because a single-cam bow has no second cam to match, it avoids keeping two cams in time with each other, though makers still provide timing-related adjustments, such as the draw stop, for tuning nock travel.

An idler wheel is usually concentric: its axle runs through its centre, so it turns at the same radius all the way through the draw. The string runs in its groove, and the wheel usually turns on bearings on its axle. A wheel that wobbles, a string that does not track in the groove, or a dry or worn bearing or bushing can show up as noise, an inconsistent draw or a tear that will not tune out.

Idler wheel lean, the wheel tilting left or right at full draw, affects how straight the string travels and can be adjusted on many bows through the cable or yoke system. Check that the wheel sits upright and tracks cleanly before chasing a tear with the rest.

Like any work on cams and strings, servicing an idler wheel or changing its string means relaxing the limbs in a bow press. Follow the maker's service instructions for your bow.

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What is the difference between a cam and an idler wheel?: A cam is shaped off-centre, so it changes the leverage through the draw and sets the draw force curve and the let-off. An idler wheel is round and turns around its centre, so it only feeds and takes up string. A single-cam bow has one of each.
Do single-cam bows need cam timing?: Not in the same way as a dual-cam bow, because there is no second cam to keep in time. Single-cam bows still have timing-related adjustments, such as the draw stop, and their nock travel is tuned through the cable and yoke system. Follow the maker's tuning guide.
How do I know if my idler wheel is bad?: Watch for a wheel that wobbles, a grinding or squeaking sound when you draw, a string that rides out of its groove, or tears you cannot tune out. Any of these is worth a check at a pro shop, where a bow press is needed to take the load off the wheel.