Why exact draw length decides accuracy on compound, what cam timing means, and why both belong in a shop's bow press, not at home.
"Why doesn't my bow just group cleanly, even though my technique is right?" With compound, the answer is more often the hardware than with recurve — specifically the draw length. Unlike recurve, where you draw flexibly within your own arm length, draw length on a compound is a fixed mechanical value: the cams stop exactly at one point, the hard "wall".
If that wall doesn't land precisely at your natural anchor point, you're fighting your own equipment — too short and you overextend; too long and you never reach the anchor cleanly. That's not a form flaw, that's a setup flaw. That's why every serious compound journey starts with a correctly measured draw length, not hours of form training on a badly set-up bow. A proper base setup therefore takes more like half an hour at the shop than five minutes at the register — time that pays off over hundreds of training shots.
Closely related: cam timing. If both cams aren't synchronized, the string twists minutely on release and torques the arrow — invisible to you, but measurable on the target.
The common formula estimates draw length from your arm span, but the reliable method is a measurement on the bow itself, with a coach checking your anchor point. Estimate formulas are a starting value, not the truth.
At the end of the draw, the cams stop abruptly — that fixed stop is your wall. It has to sit exactly where your anchor point rests relaxed. If the wall feels "cramped" or "unreachable," your draw length is wrong, not your technique.
Cam timing describes whether both cams finish their rotation at the same time. If they're out of sync, the wall goes "mushy," and the string gets a minute twist on release that torques the arrow. That's pure mechanics, not a form question.
Draw length and cam timing live in modules or rotation stops directly on the cams — under full cable tension. That belongs in a bow press, where tension is released in a controlled way. Experimenting yourself can snap a cable.
Change the draw length, and cam timing almost always shifts with it — often the peep position too. Plan these three as one package, not as separate fixes.
Alongside draw length, draw weight and timing, peep height belongs in the same package: if the peep sits too high or too low in the string, you have to crane your head at anchor to see through it — a mistake many wrongly blame on technique. The shop positions the peep to match your head posture once draw length and wall are locked in.
Never work on cables or modules while the bow is under draw tension without a bow press — the released energy can snap a cable and injure fingers. Have every draw length change done exclusively by the shop.
If you're torn between two draw lengths, go a touch shorter rather than longer. A slightly too-short draw feels uncomfortable but is safer for shoulder and elbow than a too-long one where you overextend while anchoring. For a sanity check, also measure your fingertip-to-fingertip wingspan and divide by 2.5 — that rough formula shouldn't land more than a centimeter or two off your measured draw length, otherwise it's worth a second look at the shop.
Because on compound it's a fixed mechanical value where the cams stop hard — on recurve you draw more flexibly within your own form. A wrong draw length on compound fights you on every single shot.
Technically yes on some modern bolt-system bows, but the first setup and any major change belong with a shop that has a bow press and measuring gear — safety and precision beat DIY enthusiasm.
The string twists minutely on release and torques the arrow, leading to unclean arrow flight and worse groups — regardless of how good your technique is.
After every season or whenever you notice a shift in your groups. Cables stretch minutely over time, which can slowly shift timing and peep position.
Compound: Safety — Dry Fire and the Law in Germany