Quote Originally Posted by CLT Bluesman View Post
What do you mean when you say "Binary cam system" do you mean a bow with two cams? I think I learned something here, I just can't figure out what it was. I think I learned that I want a larger ATA bow, with a smaller cam. I also have noticed the diameter of idler wheels is gigantic. Does this make a difference in lean on that limb?
Now you're getting the idea of how I think. Think of it this way. I cam or idler wheel is nothing more than a round lever exerting pressure on the limb tip. As with any lever the longer it is the less effort is needed to make it do it's work. In this case the work is twisting the limb tips. The more pressure put on the lever (wheel or cam) the more the limb tip gets twisted. This is what we observe and call cam lean. Assume that the cam is straight with the bow at rest. As the bow is drawn more stress is transferred to the cables and as the bow drops into full draw the maximum force is applied to the cables (minimum force on the string). It is at this point cam lean will be greatest as the limbs are twisted to the max. The problem is limbs are not designed to be twisted, but bent toward each other. Another problem is that the string/cable grooves should be tracking in a straight line toward each other and parallel to the riser. Such is not the case with the cams "leaning". Depending on how the string grooves are machined this causes premature wear on the string servings at best and string derailment at worst. Well, almost. The worst case is limb failure (longitudinal splitting) due to constant twisting.

So what is too much cam lean (limb twisting)? In my opinion there should be none whatsoever, but this won't happen so long as the cables are pulled to the side by a cable rod/slide or roller guard. This is the technology we have been stuck with for the last 35 years. It's always been in the design, but as bows become shorter the angle of side pull becomes more acute so more noticeable.

So why isn't something being done about it? IMO, simply because we, as consumers, don't demand it. Limb failure rates are acceptable enough that companies can just replace limbs. Limb failure borders on about 1% across the industry for all reasons. And as much as that may be acceptable to most it's not always so for the person that experiences it. So long as we keep buying bows with this old technology they have no reason to address the issue. We, as consumers, are more interested in how much shorter and faster bows can become; not how much more reliable easier to tune, and pleasant to shoot.