Im-8 And Im-7 How Different?

[Loop_Dad]

How different is it between IM-8 and IM-7 blank? I'm used to IM-8 rods. Do I feel a big difference and will I hate IM-7? I'm considering a IM-7 rod because they have the length I want.

[aavery2]

That question is nearly impossible to answer IMHO, there are so many variables other than the type of CF used in the makeing of a rod that affect a rods ability to transmit vibration.

[Loop_Dad]

That question is nearly impossible to answer IMHO, there are so many variables other than the type of CF used in the makeing of a rod that affect a rods ability to transmit vibration.

aavery2, I see your point. I don't know if you have used both IM-7 rod and IM-8 rod yourself. If someone who got and/or used both rods said "it depends", then I'll read that as the difference in the blank is probably minimal.

I'm also hoping to get some comment from some of you who might own IM-7 rod and IM-8 rod from same company with similar components.

[BASSclary]

IM ratings are generally a marketing tool for people who are unaware that its basically just some letters and a number.

If your using the same series of rods , shimano for example, its just a number to basically say this blank is overall better. Seriously, take our word, IM and modulus mean close to nothing. Some extremely high end blanks are like 50 mil modulus, and scrappy ones boast an astounding 90 mil. Point being, doesn't matter.

[SirSnookalot]

I don't think it matters either. A few years ago I bought an im 10 rod, took it to a canal and returned it to the store within an hour and bought an im 6 which I'm still using today.

The first rod was marketed as an inshore redfish rod...........really, that was a joke, a fairly popular brand too.

The rod I'm still using is also an inshore rod, my preference for canals and and slop, this one I could use for redfish.

[Delaware Valley Tackle]

IM ratings are subjective as well. It not a scientific unit of measure like inches or pounds. The only real meaning it would have would be to distiguish between models in the same line up. Modulus is a better indicator of the carbon fiber used but does not tell the whole story either. Resins, scrim. mandrels, design, wall thickness and components all factor into a quality rod. The noticable difference between models within a lineup is an individual thing. In general the jump from entry level (in St Croix's case Mojo) and mid level (Avid) is substantial and from Mid to high end (Legend Tourn)is less dramatic but noticeable.

[.RM.]

This was posted on the rod builders website http://rodbuilding.org/list.php?2 a few years back, and posted here many times by me..

Here goes again...............

Good evenin' folks,

I may be about to open a SERIOUS can of worms with this thread, but what the heck.....here goes anyway. Being in the blank distribution business, I get asked A LOT about the construction and makeup of the various graphite rod blanks that I sell. And, I have to say that whenever somebody asks me about modulus I just cringe! Here is why; It seems that about 90% of the folks that email me want to know what the modulus is of the blank(s) they are considering buying. When I ask "Why do you want to know that" they can't really give me an answer....they're just convinced that higher the IM rating is better. Here is how the conversation usually evolves:

Mr. Customer: What modulus is that blank made from?

Andy: Well, if you must know, it's about 40million Msi

Mr. Customer: What does that mean?

Andy: Well, it means the blank is made from the material you have come to know and love as IM6

Mr. Customer: Oh, that's too antiquated...I only fish with IM7 and higher.

Andy: Really? Did you know that the difference between IM6 and IM7 is not the modulus it's the tensile strength?

Mr. Customer: Really?

Andy: Yeah REALLY!

Mr. Customer: Eh Hhhmmm....erreer, uh, oh....well uh....well Bass Pro Shops says...

Andy: Forget Bass Pro shops...let's look at the numbers (at this point Andy whips out his trusty data chart that illustrates the differences between the different fibers that actually have IM designations). Here take a look at this. This comes from a chart put together by the folks at Hexcel (http://www.advancedc.../technology.htm)

The number on the far right is the modulus of the fiber, and the number in the middle is the elongation to failure or stretch.

Hexcel IM4 600 40

Hexcel IM6 760 40

Hexcel IM7 780 40

Hexcel IM8 790 44

Hexcel IM9 920 42

Mr. Customer: You Mean all this time I thought I was getting a higher modulus fiber with the higher IM rating, when what I was really getting is a fiber that stretches more?

Andy: Well, in some cases you are, and in some cases you arent. The fact is though that the difference between IM6 and IM7 is nothing in terms of modulus, and compared to IM8 it's only slightly higher. Wow...look at that IM9 actually has a lower modulus than IM8...go figure Now, many companies are using fibers with a much higher modulus, like 57 and even higher, however these fibers don't necessarily use the IM ratings. So, whenever you see a fiber with an IM rating...BUYER BEWARE! THE HIGHER THE IM RATING, DOES NOT NECESSARILY MEAN THE HIGHER THE MODULUS!!!

The point is this folks...just because you have a blank made from a high modulus fiber, doesn't means it's a good rod! And vice versa, just because you have a blank with a low modulus...even the original fiber blanks were made with (33 million) doesn't mean it's a bad or outdated rod. It's all about what the designer does with it.

I know there are some of you that may already know this, but judging from the amount of calls I get on a daily basis from folks who ONLY want IM7 or IM8, but can't really tell you why, I have to believe they don't really know what they are talking about at all. They've just been sucked into the marketing machine that leads people to believe that the higher the IM rating, the lighter and more sensetive the material, which is not always the case.

Be forewarned that there is A LOT more to graphite blank construction, performance, quality, sensetivity, weight etc... than just what modulus the fiber is. There are lots of other variables like flag patterns, and wall thickness, and resin systems, and mandrel design....It's all about the talent of the designer, and what he is able to do in terms of the sum of those variables...not just the friggin modulus!

Whewww...ok I feel better now...

My aforementioned explanation of modulus and IM ratings is by no means meant to be anything more than a brief primer for the folks who didn't realize what the differences with the IM ratings were. I hope this clears things up a bit, and I hope that some of you will chime in on this as well. Oh, here is a link to the Hexcel page for those of you who want to investigate the matter further. Do a search for IM6 and you'll get some interesting info. (if you're into that kind of techie junk).

[www.hexcel.com]

[www.advancedcomposites.com]

Now, this gives you some ammunition...next time you stroll into BassPro, and some yahoo tries to sell you a rod based on it's IM rating, ask him to explain to you why the higher IM ratings are better. When he replies by sayin' that the higher the IM rating means more sensetivity, less weight etc....just tell him that you have a blank at home made from IM2000, and see what he says.

Regards,

Andy Dear

Lamar Manf.

Tight Lines!

[retiredbosn]

If from same manufacturer I'd go for it. I have clarus and convergence rods not much difference

[Capt.Bob]

I have owned both from same makers and it really isn't much of measure of sensitivity. Less expensive BPS IM-6 and IM-8 Bionic Blade rods, I use them for the grandkids have less than 60 bucks in them and don't worry about them, great on the river bank. But see no difference in feel. both 6'^' MH.

You would be much better off relying on a manufacturer with long term proven reliability of customer satisfaction to take guess work out of your purchase. St. Croix is one such company, as long as you go with one of there rods built in the USA, a rod such as the Premier is not that expensive and come in about any weight action and length you could want, most likely as sensitive as any IM-6,7,8 and probably lighter and as strong or stronger, plus a proven 5 year warranty. Sorry but we have seen a lot of problems with the models from this company being made out of the country, plus they use lower quality hardware, just an option.

[roadwarrior]

.RM.

Thank you.

Tthat link always come in handy!

[Loop_Dad]

Thanks, folks. Now I have better understanding about IM rating.

[OnthePotomac]

This may be of some help to you:

The “IM” rating may vary among rod manufacturers, but the following values are fairly standard in the industry:

IM6 = 30+ton material in the rod (this is considered a standard modulus)

IM7 = 35+ton material in the rod (this is considered intermediate modulus)

IM8 = 40+ton material in the rod (this is considered intermediate to high modulus)

IM10 = 54+ton material in the rod (this is considered high modulus)

Beyond this level manufacturers use various ways to describe their rod strengths.

You will find rods which do not use the “IM” ratings on their rods. Instead they will use strength designations such as HMG 60 (High Modulus Graphite) which is used on Bass Pro Shops Extreme rods, or HM 85 (High Modulus) which is used on the expensive Johnny Morris rods. BPS Carbonlites are 85 million modulus, but this is not printed on the rod. Loomis goes even further and uses designations such as “NRX”, “GLX”, “IMX” and “NX” and do tell you what the modulus rating is unless you ask them. They will use the term “very high modulus” in their description of their rods.

[Hooligan]

This may be of some help to you:

The “IM” rating may vary among rod manufacturers, but the following values are fairly standard in the industry:

IM6 = 30+ton material in the rod (this is considered a standard modulus)

IM7 = 35+ton material in the rod (this is considered intermediate modulus)

IM8 = 40+ton material in the rod (this is considered intermediate to high modulus)

IM10 = 54+ton material in the rod (this is considered high modulus)

Beyond this level manufacturers use various ways to describe their rod strengths.

You will find rods which do not use the “IM” ratings on their rods. Instead they will use strength designations such as HMG 60 (High Modulus Graphite) which is used on Bass Pro Shops Extreme rods, or HM 85 (High Modulus) which is used on the expensive Johnny Morris rods. BPS Carbonlites are 85 million modulus, but this is not printed on the rod. Loomis goes even further and uses designations such as “NRX”, “GLX”, “IMX” and “NX” and do tell you what the modulus rating is unless you ask them. They will use the term “very high modulus” in their description of their rods.

That is not actually accurate. modulus rating isn't standard, and there is no industry standard. Using tonnage material to describe the graphite in rods is yet another ploy that manufacturers use. You can't talk about modulus without talking about strain rate, or hoop strength. There's not a rod out there that is 40 ton hoop strength, it's bunk...

Here's Gary Loomis talking about rods:

http://www.kistlerrods.com/fishing-rod/Gary-Loomis-talks-about-rod-breakage/subpage230.html

Ever since the introduction of the first graphite rod by Fenwick in 1974, myths about this mysterious material have been growing and circulating the globe like wildfire. How many times have you been told that the difference between IM6, IM7 and IM8 is the difference in quality standard, or that the higher the modulus, the more graphite was used to produce the rod?

With there being so many misconceptions surrounding this material, Gary Loomis – one of the world’s foremost authorities on graphite rod design and founder of the G.Loomis Corp. – agreed to lend his expertise to eliminate these myths.

Loomis began by explaining that the identifiers IM6, IM7 and IM8 are the trade numbers used by the Hexcel Corp. to identify their product and is not an industry quality or material standard, although the Hercules Fibers produced by the Hexcel Corp. are the benchmark that most companies use to compare their materials. The confusion is compounded because a number of rod manufacturers use materials produced by companies other than Hexcel and yet identify their rods as being IM6, IM7 and IM8, which by itself means nothing.

What an angler needs to understand is how the word “modulus” pertains to graphite rods. Modulus is not a thread count, as many would have you believe. Modulus basically equates to stiffness. The higher the modulus, the stiffer the material is by weight, meaning less material is needed to achieve the same stiffness of lower-modulus materials. This results in a lighter product.

“You have to remember, weight is the deterrence to performance,” Loomis said.

Stiffness also equates to responsiveness – that is, the rod’s ability to store and release energy. The higher the modulus, the faster and more consistent a rod is able to store and release its energy, which enables an angler to cast farther and more accurately.

But you cannot talk about modulus without including strain rate, or the measured strength of the material. While modulus is reported in millions, strain rate is reported in thousands. An acceptable strain rate for a fishing rod is 680,000 or higher. A graphite rod made from IM6 Hercules Fibers will have a modulus of 36 million and a strain rate of 750,000.

With the original materials used for graphite rods, as the modulus rate increased, the strain rate would decrease, resulting in the rods being more acceptable to failures because of brittleness. However, through the advancements of materials, technology and engineering design, companies are able to produce high-modulus, high-strain-rate rods. These new high-tech fishing rods are super-light, responsive, and extremely sensitive and strong.

But the misconception of brittleness still plagues them, and the reason for this is because as the modulus gets higher, the less material is needed and therefore used. This means that the wall thickness in the blank, which is basically a hollow tube, is thinner. “Remember what I said before – weight is the deterrence to performance,” Loomis said, and went on to tell a story:

“I had a gentleman come in with a fly rod that broke near the handle, and he was asking for a new rod. I examined his broken rod and knew from the break – it was splintered – that his rod broke from abuse. So I asked him how it broke, and the man, being sincere, told me it broke while fighting a fish. I explained that it would be nearly impossible for the rod to break this way. But to be fair, (I told him) if he could break another rod the same way, I would give him three brand-new rods of his choice, but if he couldn’t, that he would pay for the repairs, and the man agreed.

“So I took him out in the back by the shipping docks and handed him an identical rod. With the rod in his hands, I grabbed the blank and asked him to apply the same pressure he was using when it broke. The man was applying a great deal of stress on the rod, and it wasn’t breaking. So I asked if he wanted to apply even more pressure, and the man responded that he didn’t think he could, but he insisted that is how his rod broke.

“So then I told him, ‘We are going to break this rod, so that it breaks just like yours did.’ I then laid the blank on a rubber mat and I kneeled on it by the handle, and we tried it again but it didn’t break. Then I laid it on the concrete and kneeled on it. Examining the rod, you couldn’t see it was damaged, but this time the rod broke just like his did, and the man simply asked where he needed to pay to get his rod repaired.”

The point of this story is that these high-modulus, high-strain-rate, thin-walled rods are extremely strong and are highly unlikely ever to break under normal use. Almost all rods are damaged by other means – an angler accidentally stepping on them, hitting them against a hard surface while casting, or storing them where a toolbox or some other heavy object can slide into them. Then, with the damage done, the rod collapses while under the stress of fighting a fish. So while high-modulus, high-strain-rate rods are not brittle, they do require more care in storage and transport.

There is a graphite rod made for every angler and their lifestyle. Composite blends (a mix of graphite and fiberglass) can take a lot of abuse. Intermediate modulus rods (33 million to 42 million) with high strain rates (700,000 or higher) still offer a lot of sensitivity and responsiveness and are quite durable. The high-modulus, high-strain-rate, extremely light rods are usually a rod manufacturer’s high-end product. These rods are the ultimate in responsiveness and sensitivity, and they cost a lot more than the average fishing rod. As with anything that costs this type of money, you would want to take a lot better care of it, including using protective cases to store and transport them around.

Hopefully, you now have a much better understanding of graphite as it pertains to fishing rods, and as a result, understand the care you need to employ with their use, storage and transport. Finally, armed with your newfound knowledge, you will be able to make a much more informed decision the next time you purchase your next graphite rod.

[Ima Bass Ninja]

That is not actually accurate. modulus rating isn't standard, and there is no industry standard. Using tonnage material to describe the graphite in rods is yet another ploy that manufacturers use. You can't talk about modulus without talking about strain rate, or hoop strength. There's not a rod out there that is 40 ton hoop strength, it's bunk...

Here's Gary Loomis talking about rods:

http://www.kistlerrods.com/fishing-rod/Gary-Loomis-talks-about-rod-breakage/subpage230.html

Ever since the introduction of the first graphite rod by Fenwick in 1974, myths about this mysterious material have been growing and circulating the globe like wildfire. How many times have you been told that the difference between IM6, IM7 and IM8 is the difference in quality standard, or that the higher the modulus, the more graphite was used to produce the rod?

With there being so many misconceptions surrounding this material, Gary Loomis – one of the world’s foremost authorities on graphite rod design and founder of the G.Loomis Corp. – agreed to lend his expertise to eliminate these myths.

Loomis began by explaining that the identifiers IM6, IM7 and IM8 are the trade numbers used by the Hexcel Corp. to identify their product and is not an industry quality or material standard, although the Hercules Fibers produced by the Hexcel Corp. are the benchmark that most companies use to compare their materials. The confusion is compounded because a number of rod manufacturers use materials produced by companies other than Hexcel and yet identify their rods as being IM6, IM7 and IM8, which by itself means nothing.

What an angler needs to understand is how the word “modulus” pertains to graphite rods. Modulus is not a thread count, as many would have you believe. Modulus basically equates to stiffness. The higher the modulus, the stiffer the material is by weight, meaning less material is needed to achieve the same stiffness of lower-modulus materials. This results in a lighter product.

“You have to remember, weight is the deterrence to performance,” Loomis said.

Stiffness also equates to responsiveness – that is, the rod’s ability to store and release energy. The higher the modulus, the faster and more consistent a rod is able to store and release its energy, which enables an angler to cast farther and more accurately.

But you cannot talk about modulus without including strain rate, or the measured strength of the material. While modulus is reported in millions, strain rate is reported in thousands. An acceptable strain rate for a fishing rod is 680,000 or higher. A graphite rod made from IM6 Hercules Fibers will have a modulus of 36 million and a strain rate of 750,000.

With the original materials used for graphite rods, as the modulus rate increased, the strain rate would decrease, resulting in the rods being more acceptable to failures because of brittleness. However, through the advancements of materials, technology and engineering design, companies are able to produce high-modulus, high-strain-rate rods. These new high-tech fishing rods are super-light, responsive, and extremely sensitive and strong.

But the misconception of brittleness still plagues them, and the reason for this is because as the modulus gets higher, the less material is needed and therefore used. This means that the wall thickness in the blank, which is basically a hollow tube, is thinner. “Remember what I said before – weight is the deterrence to performance,” Loomis said, and went on to tell a story:

“I had a gentleman come in with a fly rod that broke near the handle, and he was asking for a new rod. I examined his broken rod and knew from the break – it was splintered – that his rod broke from abuse. So I asked him how it broke, and the man, being sincere, told me it broke while fighting a fish. I explained that it would be nearly impossible for the rod to break this way. But to be fair, (I told him) if he could break another rod the same way, I would give him three brand-new rods of his choice, but if he couldn’t, that he would pay for the repairs, and the man agreed.

“So I took him out in the back by the shipping docks and handed him an identical rod. With the rod in his hands, I grabbed the blank and asked him to apply the same pressure he was using when it broke. The man was applying a great deal of stress on the rod, and it wasn’t breaking. So I asked if he wanted to apply even more pressure, and the man responded that he didn’t think he could, but he insisted that is how his rod broke.

“So then I told him, ‘We are going to break this rod, so that it breaks just like yours did.’ I then laid the blank on a rubber mat and I kneeled on it by the handle, and we tried it again but it didn’t break. Then I laid it on the concrete and kneeled on it. Examining the rod, you couldn’t see it was damaged, but this time the rod broke just like his did, and the man simply asked where he needed to pay to get his rod repaired.”

The point of this story is that these high-modulus, high-strain-rate, thin-walled rods are extremely strong and are highly unlikely ever to break under normal use. Almost all rods are damaged by other means – an angler accidentally stepping on them, hitting them against a hard surface while casting, or storing them where a toolbox or some other heavy object can slide into them. Then, with the damage done, the rod collapses while under the stress of fighting a fish. So while high-modulus, high-strain-rate rods are not brittle, they do require more care in storage and transport.

There is a graphite rod made for every angler and their lifestyle. Composite blends (a mix of graphite and fiberglass) can take a lot of abuse. Intermediate modulus rods (33 million to 42 million) with high strain rates (700,000 or higher) still offer a lot of sensitivity and responsiveness and are quite durable. The high-modulus, high-strain-rate, extremely light rods are usually a rod manufacturer’s high-end product. These rods are the ultimate in responsiveness and sensitivity, and they cost a lot more than the average fishing rod. As with anything that costs this type of money, you would want to take a lot better care of it, including using protective cases to store and transport them around.

Hopefully, you now have a much better understanding of graphite as it pertains to fishing rods, and as a result, understand the care you need to employ with their use, storage and transport. Finally, armed with your newfound knowledge, you will be able to make a much more informed decision the next time you purchase your next graphite rod.

This is by far the best information I have ever read on rod construction and ratings. Thanks for posting!