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rstydog
01-21-2013, 11:52 PM
I bought an Onza 3 Pro online, new (xmas gift to self). Took some arrows and chrony'd them.

Bow is 70lb DW/29"DL and arrows were Easton carboneros 30" @420gr registering 276 fps avg. Tried two different chronys.

ATA of the bow is 33 5/8" and brace is 7 1/2". Factory spec's say these should be 33.25 and 7.25 respectively.

Any ideas why speed is down and what can I do to increase it?

Have an older Martin Phantom with magnum limbs and that is throwing the same arrows at 248fps so I was expecting the ONZA to be alot quicker.

Read all the reviews I could find and watched Ike's Outdoors great youtube clip before commiting to the ONZA.

Help welcome, returning the bow is not practible as I'm down in NZ

bfisher
01-22-2013, 08:49 AM
Well, for one thing I usually find the IBO speeds to be inflated by about 20 fps. Remember, anything added to the string reduces precious speed. String loop, nocking points, peep all slow things down a bit. The arrow is 50 grains over IBO so there's about 25 fps down the tubes right there. These cams perform better when they are wrapped up and that means playing with string/cable lengths to optimize cam orientation. A lot of playing involved and a chrono on hand is necessary.

As for the A2A being long, it could be a slightly long string and/or short cables. Again, some twisting/untwisting involved to get it right. All in all you're looking at a 30fps gain from your previous bow so that isn't all that bad. There's a thread on Archery Talk (Optimizing Cat Cams) that explains in detail just how to go about timing the cams for optimum performance. It's several years old and is meant for the older Cat cams, but the Nitro isn't all that much different. Same principles are involved.

wscywabbit
01-22-2013, 02:38 PM
First off, welcome to the forum, and to the Martin family! :)

Fisher was right on, there's a lot of stuff that effects speed, including weight on the string from string silencers, peeps, peep tube, d-loop, nocks, arrow weight, etc.; so individual set up has a lot to do with your individual speed.

The ATA and Brace height are also going to have some play as well, typically a shorter brace height will gain you faster speeds: think of it like a free gimme to your draw length... I don't know how comfortable you are with working on your own bow, or if you're even set up for it, but if your ATA and Brace are way off, you'll have to make sure your cable and string lengths are correct... a good pro shop can help with this, or you can do it yourself.

The cams themselves are VERY adjustable, and the speed range varies a lot by how the cam is set up as well. Basically, if you set the draw modules shorter than your draw length, and then move the draw stop towards the + to fine tune your draw length, it will decrease your holding weight, and your power output. If you set your draw modules long, and move the draw stop towards the -, it will increase your holding weight, and the power ouput. In short, moving the draw stop towards the - will increase your speeds.

When setting your draw length, pay attention to the cam rotation at full draw; you don't want to over-rotate past the flat part of the module, it will cause pre-mature cable wear.

A lot of info, I know, but if you have any questions post them and someone here is always able to help; after all its what we're here for! :)

Ehunter
01-22-2013, 06:47 PM
Welcome to the forum. Here's a link to the AT thread bfisher mentioned. Very useful info. http://www.archerytalk.com/vb/showthread.php?t=626601

bfisher
01-22-2013, 07:03 PM
Welcome to the forum. Here's a link to the AT thread bfisher mentioned. Very useful info. http://www.archerytalk.com/vb/showthread.php?t=626601

I knew someone would come through and post the link. Thanks E.

rstydog
01-22-2013, 07:58 PM
Thanks for the welcome and for the advice.

I found this link the other day which is really useful, will work my way thru the nitty gritty of cable twisting etc

http://archeryhistory.com/archerytalk/The_Nuts&Bolts_of_Archery.pdf

I forgot to say that as the bow is new I am still waiting for peep, sights etc and have only tied a nocking point on the string and installed a whisper biscuit on the bow so shouldnt have affected speed much at all.

Love the bow but not the hassle.

Cheers

elkslayer4x5
01-23-2013, 10:32 AM
Welcome to the site, glad you joined us here. :)

Lab Rat
01-23-2013, 11:32 AM
Find a good arrow speed calculator online and plug in the actual draw weight, the actual draw length, the actual arrow mass, and the actual string weight adders and you may find that you are very close to where you should be. I put an IBO rating of 330 fps, 29 in, 420 gr, with 50 grain of added string weight and got a actual speed of 280 fps. Remember that when we start throwing leaches on the string at 26 gr each, and a d-loop at 5 gr, and a peep at 10 gr it can add up rapidly. I think I have read the for every 3 gr added slow you down 1 fps. The IBO is done with a single nock I think. As the others said these cams can be tweaked and they are easy to optimize. With your specs out a little you will probably find room to twist it back closer to specs. Bottom line you aren't that far off.

Mike G
01-23-2013, 02:50 PM
Thanks for the welcome and for the advice.

I found this link the other day which is really useful, will work my way thru the nitty gritty of cable twisting etc

http://archeryhistory.com/archerytalk/The_Nuts&Bolts_of_Archery.pdf

I forgot to say that as the bow is new I am still waiting for peep, sights etc and have only tied a nocking point on the string and installed a whisper biscuit on the bow so shouldnt have affected speed much at all.

Love the bow but not the hassle.

Cheers

First ... Welcome!

Recently I did some checking on the whisker bisquit. I was thinking of going with a full capture rest for hunting. I lost about 10fps with a whisker compared to a prong rest. Granted I didn't play around much with the bisquit with making sure the bow was tuned perfect to the rest, just centered it with square and level.

So this may be some of the loss. Otherwise as already stated with the bow spec of 330fps, 29" DL, 70#DW, 420grn arrow and going with 5grns for tied knock takes it to 295. Subtracting 10fps for bisquit = 285.

Lab Rat
01-23-2013, 04:15 PM
When I was tweaking my Alien Z by twisting the cables I went from 265 fps with a 420 gr arrow and 30 inch draw set below 60 lb. My specs were off initially because of some other tweaking and changing that I did to the cable guard. I was able to twist the cables into spec, made sure that the cams were close to being in time and then the bow shot 275 fps. My point is if you get your bow close to specs it should be close to calculated speed. I wouldn't get to hung up on 5-10 fps. What you will really love about that Onza is how accurate that bow is and how well it holds.

Ehunter
01-23-2013, 07:05 PM
Following the advise in the thread I posted earlier, I gained about 24 fps with my old Cat Cams, and about 18 fps with the Nitro cams. Was shooting a 386 gr. arrow, 28.25 draw @70# and getting 301-303 fps after tweaking everything. Probably could have gotten a few more fps, but I was more than happy with those speeds. Basically, I do a little adjustment, then shoot the bow. You will probably find a spot in your adjustments that just feels the best, it may not be at the fastest speed, but that's where I leave my bows. If you adjust past that spot, you'll know. I did it on all of mine, then backed it off to where it shot and felt best for me. ATA and BH were never spot on specs either. Always just a hair off with both. It's just a matter of what feels and shoots best for you.