April 24, 2013

Rod Flex Index

I recently posted a chart on how I felt the rods I have reviewed could be placed in relation to each other. After receiving some comments and suggestions from readers I have revised the table. The modification made is what I call the "Rod Flex Index". This is a way to try to keep rod actions independent of their respective lengths. For instance, a 450 cm rod that has a Common Cents Scale (CCS) of 15 pennies will feel and fish much differently than a 240 cm rod of 15 pennies. Yes, they are both 15 penny CCS rods but the length factors into their casting actions. The Rod Flex Index tries to neutralize these differences.

Basically, the Rod Flex Index (RFI) is the CCS penny rating for the rod divided by the length of the rod in meters. The lower the index number the slower the action, the more full-flex the rod -- the higher the number the more fast and tip-flex the rod. Using this index will let a fisher immediately have some idea of how the rod will feel when casting and what others rod he or she may have that might be similar. Slow or full-flex rods have an RFI of 2.5-4.5. Moderate or mid-flex rods have an RFI of 4.6-6.5. Fast or tip-flex rods 6.6-8.5, and very fast or minimal-flex 8.6+. Using the rods described above as an example: TUSA Ito 4.5m is a 15 penny rod. The Shimotsuke Kiyotaki 24 is 2.4m and also a 15 penny rod. Using the above formula, the Ito at 4.5m has an RFI of 3.3 (slower end of full-flex rods), while the Kiyotaki 24 has an RFI of 6.3 (faster end of mid-flex rods). The Kiyotaki 24 is a much faster, tip-flex rod while the Ito at 4.5m is a very slow, full-flex rod, yet they are both 15 penny on the CCS.

Some rods maybe categorized as a 5:5, 6:4 or 7:3 but by their RFI may fit better with rods of a different category. Take the Nissin ZeroSum 360 7:3 (one of my favorite rods) for example. It is categorized as a 7:3 rod but its RFI is only 5.2. That puts it in the range of some 6:4 rods! When you cast the ZeroSum 360 7:3 you can immediately tell that it is not a classical 7:3 rod! The RFI tells you this before you ever pick it up! Also, the TUSA Amago has an RFI of 7.6. That puts it in the 7:3 category, not the 6:4 category.  When you cast it you can tell it's not your typical 6:4 rod.

As you can tell from my last table, I have moved some of the rods. Why? It's hard to argue with data. The RFI caused some of the rods to move -- usually not too far -- a little to the right or to the left.

I think the RFI is a good way to compare rods to each other. One of the challenges of tenkara is that the rod ratings are subjective and therefore are not always as billed. The CCS is a good approximation of a rod's overall flex, but it must be corrected for the rod's length to be able to compare its "real" flex action to other rods. The RFI does this.

Here is the table modified for the RFI. Labeled is the manufacturer, rod, type of rod (T=tenkara, K=keiryu, S=seiryu, ( )= all purpose), CCS penny rating, then RFI score. The full-flex category has been divided into slow and very slow, but they are really in the same overall category. I might have to adjust some of these scores if I measured any of the CCS penny ratings incorrectly. There is at least one rod on here where my CCS rating is different from TenkaraBum. We are still trying to figure out why. Click on the table to make it larger.

Rod Flex Index
TUSA=Tenkara USA; AFB=AllFishingBuy; TW=Tenkara Worldwide




So, what do you think? Does it make sense? Is it useful to you? I'm sure that as I get more experience with even more rods I'll continue to modify the RFI, but I think this is a good start. As always with any rod, if you want to know how it casts, cast it!




11 comments:

  1. Tom,

    You have been putting a lot of thought into fine tuning your Rod Flex Index. Really breaking down the rod flexes to quantitative numbers for ease of comparison. I like it. I see you have the Suntech Suikei 39 listed. Looking forward to your full review.

    Charlie

    ReplyDelete
    Replies
    1. Thanks, Charlie. The review is coming up shortly.

      -Tom

      Delete
  2. I think it fits rather well. My experience is that the Diawa Kiyose 43 is stiffer at the longer length and the Suntech Trail Master does soften up at the longer lengths. And the RFI would support that.

    ReplyDelete
    Replies
    1. Yes, it seems to hold up well for these rods!

      -Tom

      Delete
  3. Great article and implementation of my method for the correction of length with the CCS system! Now I can see how my dainty collection of rods stacks up against the myriad you have tried. Thanks!

    - Jason Fitzgibbon

    ReplyDelete
    Replies
    1. It's a good system, I think. I would hope that you, or anyone else, who have other rods that are not on this chart would perform the CCS penny test on that rod and send me the data. That way we as a community can continue to compile data for these rods. I think it would be great to have these data for most all fixed-line rods used in tenkara. It would be a valuable assest for anyone wanting to or looking into buying a certain rod!

      -Tom

      Delete
  4. Some very interesting data you have compiled Tom. I can see the value in it and applaud all the hard work in putting the hard numbers on paper. I think it will be very useful as a point of reference for folks as the consider various rods and work to find what action they like in a rod.

    One thing for folks to keep in mind is that this is still only part of the picture of what a rod will "feel" like. The balance of the rod is still a variable that needs other measurements. I have owned and or fished with most of the rods in one of your columns. several of them were very well balanced and lend themselves to easy, relaxed casting for many hours. While others with near identical RFI numbers were not nearly as well balanced and or much heavier and would quickly fatigue the casting arm. This would soon turn into sloppy casting. It's been some time since I have seen you use your Cantilever test on a rod but that may be helpful numbers to some as well.

    Paul

    ReplyDelete
    Replies
    1. I agree, Paul. Although trying to come up with a easily measured, robust, reproducible standard for measuring a rods flex is great, it still behooves the tenkara fisher to cast a rod to really feel how it will flex and balance in their own hand.

      -Tom

      Delete
    2. I see your point and perhaps the cantilever would be a little to tricky to map. I wonder if just charting the balance point of the rod would help though. As you said each person will grip a rod different and at varied points along the grip. I actually grip some rods very different than others. But knowing the balance point of a rod could help to gage another aspect of the rods feel. I would imagine that would not be to hard to set up a simple way to measure the point at which the rod balances on and how far up from the rod butt that is.

      I totally agree that no amount of statistical data will compare to actually fishing the rod. But from a person that is selling the rods I can attest to the number of folks that want to know what a rod feels like before having to pay for it. Even in the regards of walking into a store and wiggling it...if you lucky getting to put a line on it and give it a few casts, that still can not come close to having fished it for hours on the stream and how your arm will feel afterwards.

      There are times when you may want or need to fish with a stiffer rod and times when you want a softer rod. Knowing the flex is a big part of that...more so than as you have said an arbitrary 5:5 or 7:3 will really tell you. But also knowing if one rod may be more fatiguing than another could be useful as well.

      My $0.02 for the day. ;)

      Paul

      Delete
  5. Very nice work Tom.
    I agree with Paul that the cantilever effect test would
    be a plus on this table.
    Congratulations.

    ReplyDelete
    Replies
    1. Thanks, Carlos. I'll try to revisit the cantilever issue in another post.

      -Tom

      Delete