Cheetah Speed

[Highlander]

I was kind of shocked at my arrow speed from my Cheetah. Shot 2 arrows through the chrono: First arrow was a Easton Epic ST 400 /w blazers in which I weighed just before I shot it, it weighed 370 grn. 242 fps. The second arrow was a carbon express 6075 with 4 in. vanes, it weighed 380 grn. and shot 246 fps. I do have the limbsaver string leeches installed on string and a D loop. I was expecting a little faster, something like 270-275 or so. Could my short draw of 27 in. be a major factor in the speed or lack there of ? I also had the draw weight verified to be at 70 lbs. What if anything can I do to get just a little more speed out of this bow ? Increase draw length ? Heavier Arrows ?

[Montalaar]

Just to your question:

Never increase the draw length if it is not necessary for your shooting form. A longer draw length will result in longer arrows and an inconsistent shooting form that will lead to nothing useful.

[Highlander]

Montalaar,
Thanks for the reply and I do agree not to change draw length, maybe I'll have to shoot heavier arrows

[dbd870]

As Simon said you need to shoot your proper draw length. Too many people shoot draw lengths too long chasing speed - your accuracy will suffer. A heavier arrow will reduce speed and you can only go down to 350 without voiding your warranty so you're about as light as you should go. What year is your Cheetah?

[dbd870]

Oh, an 08 I see it. I would expect about around 260. Do you have a tube peep by chance?

[Highlander]

No, tube peep, a Tru peep served in. I also have a Martin STS on the bow also.

[bfisher]

No, tube peep, a Tru peep served in. I also have a Martin STS on the bow also.

I wasn't going to get into this too deeply. I figure if a guy wants speed he should look at speed bows in the first place. However, being as I'm here......


And you don't have a speed cam I might as well see what I can do to help. A lot depends on how much you want to nitpick and adjust. Also the constant use of a chronograph is almost a must.

Some of my suggestions might not be worth a hoot to you, so use only the ones you want. You may not want or be able to afford some of them. And no one thing is going to make that much difference but a combination could gain some decent speed. Let's see. Where to start?

OK, the bow is maxed out at 70#. Have you actually weighed the bow and actually measured the draw length? Have you made sure the string is tracking correctly off the idler wheel? Is the cam timed properly? These are things that should be done as part of your initial setup.

The rest. You could go to a drop away and gain some. WB does cause more drag so robs the bow. I went from a prong rest to a dropper on my one bows and gained 4 fps.

Now the string. You could get a custom string made by guys like Bucknasty on Archery Talk. Have it made from BCY 8125 and have it served with only a 3" serving. You're using a loop so you don't need a lot of serving. You may have to measure just where you want it and tell Bucknasty. No need to replace the cables. This alone might gain you as much as 10-12 fps.
I did this on my ShadowCat a couple years ago and gained 11 fps. The folloing year I did it to my P3 and gained nothing. Hit or miss, but still a good string.

Now the string loop. How big is it? The loop should allow you to hook your release on the string and not hit the arrow nock. You don't need any longer than that. Any more is just extra baggage and if shorter may let you increase the draw length just a bit to maintain your anchor points.

Only thing you should need to do is reserve the area where the STS bangs the string. About 1 1/2" should do it.

Let's see. You could either remove the leeches altogether or move them closer to the cam/wheel and use them as speed balls. A check with the chrono would tell you where there may be a sweet spot.

I would mention changing the Fletcher to a Meta Peep, but this is getting too picky and not worth the price. I've got both and the Fletcher is as good as any.

You could do something like twist the cable up a little more to over rotate the cam. We call this overclocking. Depending on how much you twist it will increase the poundage and draw length a bit, but just don't get carried away and you might gain something there. Be aware that overclocking the cam may give you a little more vibration and noise so don't be annoyed at it. Either you like it or you don't.

Now we get down to a very contraversal subject---arrow weight. By factory warranty you are required to shoot at least 5gr/lb or 350 gr at your 70#. Problem I have with this is "at what draw length"? It's a well known fact that longer draw means more speed. That's because the longer draw stores more energy (stress?) in the bow. So naturally a shorter draw archer stores less energy in the bow. This means there is less energy to impart to the arrow and less speed. So taking this into account I ask, "Is the 5gr/lb rule an absolute?" Meant for everybody, regardless of draw length? And what about cam style? Speed cams mean more energy. Softer cams mean less energy. I'm usingthe term energy to mean "stress in the bow".

So , that being said, or asked, have you ever heard of the "AMO Minimum Arrow Weight Chart"? Log onto www.bowjackson.com and get a look at it. I already did and put in your specs, 27" draw and 70#, Energy wheel (cam), so I know the results.

While you're there also look at the Easton Tuning Guide and bookmark it. You won't find a much better guide detailing how to basically set up a bow and tune it.

These are just some of the things that you can do that can possibly gain you a significant amount of speed. Taking and educated guess I'd say maybe the 30 fps you think you should have.

Here again. Every time you make the slightest change you need to verify what the results are by shooting over the chrono. Do one thing at a time and record the results. Attention to detail is what's all about.

These are but a list of what I have in my little pea brain at the moment. There could be more, but that's enough for you to digest at the moment.

Have fun experimenting. It is fun learning what does what---at least to me.

Barry

[dbd870]

The WB may cost you a few fps, but that still seems a little slow to me. Figure -30 for draw length, -10 for the arrow, -15 for stuff on string and WB: that puts you at 315-55= 260fps.

Obviously that's not exact but with my MOAB 28" 60# 312gr arrow (no peep):
Figure -20 for draw length, -20 for draw weight, -10 for stuff on string, +10 for lighter than 350gr. arrow: that puts me 315 - 40 = 275. I in fact run 276-277 over my chrono so Martin's IBO rating appears to be reasonable.

I know it's not the same bow but it does have the same cams and it seems Martin got it right on the MOAB. Now I'm not the best at guessing speed deductions - I don't think I should be 15fps off. I wonder if you cam is timed correctly?

I see Barry beat me to a response, remember Martin doesn't warranty the bow if you go under 5gr/lb.

[Highlander]

Barry,
First let me thank you for your detailed and very helpful info. I hope I'm not being too nit-picky trying to get a little more speed. I just want my bow to function to it's potential. I also hope I'm not asking too much out of this bow. I took the string leeches off and will chrono tomorrow with the same arrows. I also have the cam looked as well. I do have a zebra hybrid string on it and served where the STS hits. The loop is just the right size. I am familiar with the 5grains per pound of draw weight rule. My lightest arrow is 370 gns and much louder than my 380 gr. I will check out those sites and do some studying. Thanks again Barry !!

Chip

[bfisher]

Barry,
First let me thank you for your detailed and very helpful info. I hope I'm not being too nit-picky trying to get a little more speed. I just want my bow to function to it's potential. I also hope I'm not asking too much out of this bow. I took the string leeches off and will chrono tomorrow with the same arrows. I also have the cam looked as well. I do have a zebra hybrid string on it and served where the STS hits. The loop is just the right size. I am familiar with the 5grains per pound of draw weight rule. My lightest arrow is 370 gns and much louder than my 380 gr. I will check out those sites and do some studying. Thanks again Barry !!

Chip

No apologies necessary around here Chip. Part of my enjoyment these days is passing on some of the knowledge I've acquired shooting these things for 35 years. Now just a bit more advice.

Keep an eye on the Zebra string. Once you get your cam located where you want it take a pencil and draw a line on the side of the cam where it passes through the limb fork. One on each side of the limb. That way you'll be able to tell if the string creeps or not. The pencil marks will move, usually with the draw length getting longer. Another indicator of string creep is when the peep starts rotating. With a good string the peep should not rotate more than about 5 degrees when the bow is drawn.

I'm not going to chastize you, but even most of the knowledgeable Mathews guys aschew Zebra strings. They have a bad reputation for creeping----a lot and forever. So keep an eye on them. Maybe you'll be like a few and have a good set.

As for the arrow weight and noise? Something else is going on. You should not be able to tell any noise difference with two arrows only 10 grains apart.

Hey, I applaud you for trying to get the best performance out of your bow. They are toys and that's what a lot of us men do. Play with our toys. There is nothing wrong with tinkering. That's basically how I've picked up what I know. There was no internet back when I was in y prime. Learned by doing. A good example is the FireCat I'm shooting now. I've had three different rests on it in the last four days and two different sights. I've got drawers fullof stuff to try.

Anyway, I'm sending you a PM. Wish you luck with the bow. Keep coming back and report your results. That's another way I learn---from others.

Barry