Bow ATA length to draw length

[bigW]

https://www.archerytalk.com/threads...ng-angle-comparisons.5965300/#post-1113208603

size of the cam definitely matters (see string angle for smaller Bowtech cam vs. Mathews cam), but the difference comes not only from the size of the cam, but also from the different brace heights (which defines the actual length of the rest position. of the nock to full draw for the particular DL).

 

[Dylan Sluis]

that might be the case for some bows, especially for ones with a less sophisticated cam system that takes the additional inches for the longer DL just from the valley, however for most of the modern bows a potentially less "comfortable" draw cycle at longer DLs / higher poundage is just based on the fact that "a bigger bang" usually always comes with a trade off. Don't forget: a longer DL can also allow you to shoot less poundage for the same speed, plus allows yo to shoot e.g. a Bowtech in comfort mode instead of performance mode, thus making the draw cycle even easier.

This is very true. Longer draw lengths can help you achieve incredibly fast arrow speeds even if you back your poundage down a little.

 

[AaronMColeman]

O

If cams were that different in size, it would make a difference in string angle. Obviously cams are different sizes, but not anywhere near that different in size, so string angle from cam size is minimal. Another thing that will affect string angle is how much your limbs bend at full draw. Some bows limbs bend more then others. This will also be minimal but is another thing that contributes to string angle.

I have an older Ben Pearson bow with smaller cams 33" ATA, I have a new bowtech with larger cams 33" ATA. Limbs on the old bow bend a lot more and are much longer. I can 100% tell a difference in string angle between the two. Maybe the cams, seems like the limbs are a big influence to, but definitely sharper angle on the old bow with smaller cams (and more flex in limbs)...so a lot of factors.

 

[bigW]

O

If cams were that different in size, it would make a difference in string angle. Obviously cams are different sizes, but not anywhere near that different in size, so string angle from cam size is minimal. Another thing that will affect string angle is how much your limbs bend at full draw. Some bows limbs bend more then others. This will also be minimal but is another thing that contributes to string angle.

the movement of the limbs is a function of the geometry of the genuine ATA, cam size and the result of DL minus brace height - they just bend as much as this geometry requires, if they wouldn't bend they would obviously break, hence they are not responsible for the various string angles.

Eta: I have to correct myself - just made a sketch and yes, various bending (as the movement of the axels) itself does indicate a varying string angle. However, the magnitude the axels move out of their rest position (the bending) is defined by the geometry of the cam system (bigger cams usually "store" more string) and the targeted DL respectively the result of DL minus brace height.

 

[5MilesBack]

So when you go to build new arrows how much of a pain is that? Can you even cut them short enough to get ideal spinning arrows? Curious because I am going to be building some for a friend but I’ve never assembled arrows that are this long. It will be a new challenge to build an arrow that flies good, that is also super long and all the inherent issues that go along with it.

I shoot 30" carbon to carbon arrows. I roll and spin the uncut arrows with fixed blade BH's to see if there's one end that wobbles more than the other. Then I cut them from that information. I also always buy the best straightness and tolerances that I can find. Beyond that, most every arrow set I've ever put together has spun true initially. I won't tolerate wobble.

 

[5MilesBack]

What I meant is the feel of the bow changes when you max out a cam on draw length. The draw cycles don't feel quite as good when you max out the cam. The draw cycle will still feel ok, but not as good as for say a draw cycle that is under the max DL for the bow.

That depends on the bow. I would agree that it seems like some manufacturers just throw on a different cam and call it good to get to a 32"+ draw length. The valleys can be short to nonexistent, very little letoff, harsh draws, and horrible cam lean........just to name a few issues I've seen with that. However, take a bow like the PSE Freak SP that was designed for long draw lengths and I've heard from shorter draw folks that say the same kind of negative things about it with a short draw. I have four bows that are all set to 32"+ draw lengths, and they all draw, hold, and shoot really well.........maybe it's because they're LH models.

 

[Legend]

Not true. Short ATA bows have acute sting angles compared to longer bows, cam size doesn't change that.. Guy on AT measured and posted the string angles on about every bow made last year. The shorties from Mathews all had significantly smaller angles.

When comparing you just need to look at the distance between cams at full draw. Pretty simple stuff. Not sure what there is to disagree with?

 

[406unltd]

I shoot 30" carbon to carbon arrows. I roll and spin the uncut arrows with fixed blade BH's to see if there's one end that wobbles more than the other. Then I cut them from that information. I also always buy the best straightness and tolerances that I can find. Beyond that, most every arrow set I've ever put together has spun true initially. I won't tolerate wobble.

Ya only so much a guy can do at that length. I do the same with the bh to see what I need to cut off. Even then no matter what brand I buy I have quite a few that aren’t the best spinners and won’t see the quiver for season. I always buy the straightest and I cut them at 29.5 with my 30.5 DL.