# Bow String Length- for vintage Bear Magnum Compound 4-wheel (with photos)



## FS560 (May 22, 2002)

This bow is apparently the hunting version of a Starfire that was produced for only one year or maybe part of a year about 1978 or 1979. The Starfire that I have is purported to be 50" but I may not have actually ever measured mine, because I did not like it. It was rough shooting, probably because of the longer butt wedge in the limb, which make the working section of the limb much shorter, even though the overall limb length was the same as the Tamerlane II/Alaskan.

You have already done the string length excercise with this bow that I suggested for your Alaskan.

One thing that confuses me is the wheels. I do not remember Bear ever using a wheel like that in those years, but then I may just be crazy. Even so, you should be able to get it to work with those wheels. Non step round wheels are really still non step round wheels.

Regarding letoff, 35% was normal, although I have no idea concerning your wheels.


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## Steelhat (Jan 24, 2006)

*Bow String Experiment #1- An Adjustable Bow String for Compound Bows*

Ok - - I admit it first thing: This is not fireable.

Now, having said that, I will say that was an interesting experiment that I always wanted to try at least once. This became a good candidate.

I used 452X strands away from both ends of a major turnbuckle to create an ATA evaluation bow string. It can adjust from 48" down to 44" in total length.

What good is a non-firing bow string? It believed it would be a great way to get draw-force curves on a bow drawing machine. 

I used 452X, with no twists in the string, so it would be non-stretching. The theory is that I could remove it in its final length and then measure it. THen, I would build a Dacron (or other product) bowstring of the finally-agreed to length, etc. The vintage bow would never be fired with this 452X. This is just a "lab" string.

1. By changing this bow string length, and then returning/re-tuning the bow to a specific draw length (in this case 29"), I could measure the resultant max draw weight and holding weight.

2. Let's go back to the main goal - - to find out why this bow is not drawing 50+lb at max draw. It seems the limb number stated would permit this normal draw weight. I was concluding that it must be the bowstring length that is wrong.

3. I am showing the bow in these photos with the final (best) max draw weight orientation, and trying different bowstring lengths, every 1/2". 

The highest draw weight measured at 29" DL was when the turnbuckle and 452X simulated a 45" bowstring length, providing 50" ATA. This only produced a maximum draw weight of 42-lbs. (Before this "adjustable" bowstring, I could not get over 33-lbs max. So, that is a slight improvement.)

4. But, look at the resulting Brace Height. It is between almost 11". 

At this point, it seems to me that the increase in draw weight is because I am really start to crank the limbs down at this BH. What do you think?

Does anyone have a similar original model Bear on which they could tell me their ATA or BH, as comparison? I feel like I am trying to reverse engineer values that someone might have hanging on display.

Anyone have any thoughts about the idea behind my use of the adjustable bow string?

Oh yes - - you may be asking -- how do I get three hands to hold both eyelets, and then also turn the turnbuckle? I should have taken a photo of that. Ifigured out that I can put two very long screwdrivers in one hand, and then turn the turnbuckle center piece in the other. Each screwdriver tip is through one of the two eyelets, so I can hold both of them still with one hand.


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## skip5515 (May 30, 2007)

*Bear Bow*

Jim is right the wheels on that bow are not the wheels that came on it they used a step wheel and it had marks for timing it and the wheels were larger as the wheels you have appear to be about 1 3/4" in Dia., I was with Astro Bows back in the 70's and remember seeing the bows from Bear as George Pappenfuss was a young amater at the time and he had a lot of Bear Bows so I did some playing with them and the wheel you have if you measure the axle holes I believe will have one side set out father than the other side giving you a different % of let off. I think that you will have to increase the wheel size and try to hit a brace heigth of about 9" with the wheel rapped with in a 1/8" of touching and I think that you will find the poundage you are looking for. Now thats my 2 cents worth after going back about 30 years of playing with Bows. I hope it helps you.


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## rock monkey (Dec 28, 2002)

i wouldnt recommend using anything but dacron/B-50 for the strings. the 'harder' materials like 452+ will make short work of the teardrops.


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## Steelhat (Jan 24, 2006)

thanks for your input on 452X. I agree completely. I was just using it for this bow string evaluation jig, so I could take not worry about stretch if I took the final turnbuckle-string-length off the bow to measure. The final bowstring will be B-50.

What's the current thought about Fast Flight and teardrops?

Thanks, for any and all ideas.

Anyone have an original of this bow that they can measure the bowstring on?

Steelhat


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## Steelhat (Jan 24, 2006)

*Thanks Skip5515!*

Thanks for that valuable input! I really needed it. Thanks.

Steelhat


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## jmoose77 (Apr 3, 2004)

1982 Bear Magnum is listed with a 50 1/2" ata and a amo string length of 46". Looks like the starfire and magnum shared the same wheel for that year.


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## jmoose77 (Apr 3, 2004)

The wheels look the same on the starfire and magnum and i just read that the starfire was 40% let-off and adjusted to 50%. The magnum was 50% and adjusted to 60% let-off. 
60% let-off? WOW! That's pretty good for the early eighties. 
I hope this info helps and good luck with your search.


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