July 6th, 2011, 03:43 PM
Olympic recurve tuning
I am shooting a 34 pounds recurve, medium 990 TX limbs and 25 inch GMX riser, right hand. Draw length is around 27.5 inch, arrow length is 29.5 inch. Brace height of the bow is 9 inch.
I have ACE 670 arrows with 120 grain points and K-vanes, which i had a bareshaft impact at 30m 80cm target face on the stiff left side at around the red/blue 6-7 ring.
Recently i upgraded my stabiliser with some weights both on the side and long rods, 25 gramm on the sides and around 70 on the front, previously i had no any weights on them at all.
What i realised is that without any other change on the setup, the bareshaft started to impact the target face on the white 1-2 lines on the left, showing much more stiff reaction then without the weights on the stabiliser.
My questions would be:
1 - does this make sense at all? Can stabiliser weights have such effect?
2 - how bad it is to have bare shaft on the stiff left white at 30m....?
3 - any thoughts for possible ways to get back to fairly better tuning for the arrows?
4 - if no way with this arrows, what spine of arrows would make the bareshaft to the centre if 670 ACE is in the white on the stiff side?
p.s.: i really would like to keep the stabiliser weights, i love now how the bow reacts, it feels really balanced this way, and also sight picture i find is much more stable then before.
Thanks in advance:
July 6th, 2011, 04:10 PM
Stabiliser is Cartel Balkan multi rod type if that counts, similar to Beiter.
July 6th, 2011, 05:23 PM
Hi Neo, any changes on the bow will make the arrow shoot differently off the bow. That said, if your fletched were in the yellow at 30 meters and the bare shaft in the 6/7 ring, then those arrows are too stiff for you to shoot well especially as you shoot farther distances. You would change arrow spine, as i think thats too much to be able to adjust from the bow poundage or from changing the point weight..
July 6th, 2011, 09:49 PM
Neo888 -- I have a very similar set up - 25" Matrix riser, 34# med. G3 limbs, 27.5 DL. I was shooting 780 ACE's with 120 gr points and they were a little stiff but I lived with it. I got a 25" Formula RX 34# F3 limbs, etc. -- same arrows were weak to the point of having to cut a bit off of them to tune to that bow.
I think my Matrix set up is closer to your set up and I think your 670 ACE's may be too stiff for that poundage. Just my opinion. I'm no expert.
July 7th, 2011, 03:23 PM
Thanks for the responses. Looking to it from another point of view, what poundage would get my setup to have these bare shaft to the center? Maybe would be better way to go to go up in poundage with stronger limbs.
July 7th, 2011, 03:52 PM
670 should be spot on or slightly on the weaker side at 29.5 length (even if you include point in your measurement, which you shouldn't), according to charts and my experience, if cut from the front.
Adding weights might cause you to find that you have/had clearance issues, or you are/were torquing the bow and weights changed the situation.
Check for clearance first. Then go up and down the tuning range and check if it behaves irrationally. If it does, then we know that something needs doing. If it doesn't, tune to nearest acceptable point. If it stays in the stiff, you shouldn't worry too much about it, they will probably group just fine.
July 7th, 2011, 04:27 PM
him having way too stiff arrows will be more prone to clearance issues with a finger release. Arrows that stiff will not group well as he shoots further out from 30.
I know, i use to shoot a 450 Xten with 3 inches cut off the back at 54 lbs. My groups were great at 30 and 50, but 70 and 90 horrible.
Tuned bows and arrows are a must if you want to be competitive and shoot your best. I think its misleading to tell him its ok if he shoots that stiff an arrow and it will still group.
He should fix the problem with a new arrow spine.
Unless of course he doesnt want to be competitive and shoot the best he can. Then just fling any old arrow and have fun. Dont worry about tuning at all.
July 7th, 2011, 05:13 PM
Of course tuned arrow will be better, but it really depends what level you are shooting for.
I sense he's not trying for olympics, so shooting less than perfectly tuned arrows will make little difference. When the basic tune is ok, then he'll know better which spine move to. For instance, I can score about similar practice scores (~310 on 70m, ~320 on a good day) with same length, point etc aces in 370 and 430 spines, the bow being tuned to 430, without noticing more than 3-4 point differences in averages between the two sets of arrows. Sure, that makes a huge difference at 340+ level, but for me.. not really.
Weak tune, on the other hand, will be far more critical in various aspects.
Last edited by zal; July 7th, 2011 at 05:19 PM.
July 8th, 2011, 12:47 AM
perhaps true, but you are shooting a 430 that the bow is tuned to , and then shooting a weaker shaft at 370 that scores similar. You are not shooting the 370
and the bow tuned to it, and then shooting the stiffer 430 and getting the same scores.
the weaker arrow will bend around the bow riser easier, the stiffer arrow will have contact with the riser giving clearance issues. but its up to the OP to
change what he will.
July 8th, 2011, 01:04 AM
Thanks again for all the valuable inputs, i believe i dont have clearence problems, but of course i can always fail on that.
Could you give a range of suggestions that if with the given setup at 34 pounds the bareshaft is at the white at 30m what poundage would poosibly get the 670 ACE to the center for me?
Is it 38 range, or more close to 42...?
July 8th, 2011, 01:37 AM
based on what you describe, i would say you need to be in the 44lb range.
July 8th, 2011, 06:24 AM
Well, 370 is STIFFER than 430 it is tuned for... Check your facts first, man.
I've helped several people tune 29.5" arrows at 34-38# and they usually go for 670 or 620 at the higher range. 44# would be at 520-470 range, if your arrow length stays at 29.5" as you stated. Closest I can think of was 35.5lbs out of extreme bf's and 29.5" arrow length, 120 points, k-vanes, and 620 shaft. Perfect bareshaft tune up to 70m.
Eastons charts and selector suggests 620-670 for your specs.
Check for clearance (even if you don't notice any problems, there might be second shaft contact) and centershot first. Check that there is no additional contact to your finger tab, clothes etc. Then check with different type of vane (k-vanes are prone to strange clearance issues). Your spine 'should' be spot on.
July 8th, 2011, 12:33 PM
Zal, youre right. 370 is stiffer spine than 430. I stand corrected.
July 8th, 2011, 03:11 PM
Just a quick update, i tried and put on a 42 pounds G3 limbs, bareshaft landed now on the soft right side at black/white border....
Tried to harden up the 34 limb bolting all the way in (guess to around 36 pounds or so), bareshaft stiff again but only until black blue border, at least not white.... (all above tests were at 30m again)
Surely you guys are both right, and maybe 670 should be spot on but definetely it is not, and i got pretty much the same reading all the time on bareshaft with clear moving with the poundage to the logical direction, so if it is a clearence issue it must be also very consistent.
I guess the only real good solution for me is to go to a weaker shaft, even if it is purely because of my shooting, and 670 should be perfect.
So my last question (i promise ), and really thanks for all your time until now, with the above mentioned bareshaft impacting with different strength of limbs, you say that at 34 pounds the good spine for me would be 780? Or does the tests written above change this number advice?
July 8th, 2011, 09:52 PM
If adding stabilizer weights changed the dynamic spine of the arrow (i.e. reaction you get out of it), then it is fairly possible that it changed something in your form or release. Shoot a bit and see if the situation changes as you get used to the new weight.
That is what's been puzzling me, its perfectly normal to have to tune a size stiffer or weaker as standard charts say (personally I shoot one spine weaker than charts say, by at my draw length of ~33 I'd be more than surprised if they'd be accurate at all), but for something to alter dynamic spine that much, has to have more effects than just weight. Sure, you can change dynamic spine by weights in the bow, as that at least changes dynamic tiller, but to have such a big effect is unusual. Few years ago, when I tested that, I could see few cm at most variations in bareshaft at 30m, even with some dramatic weight changes.