Determining the line weight of a bamboo fly rod.

A good friend and fellow bamboo rod builder (Skip Hosfield) sent this to me.  I’m not sure who developed this procedure so I can’t give him/her the credit they deserve…it works quite well.

1)  Accurately measure the distance from the rod tip to the front of the cork grip (not the entire rod length).  Divide that number by 10.  Example:  96″/10=9.6

2) Clamp the rod grip to a table so that the rod is horizontal next to a wall.  Mark the position of the tip of the rod on the wall.  Put a paper clip through the top of a small plastic bag and hang the paper clip and bag to the tip of the rod.  Slowly add small weights (coins, washers, nuts, etc.) to the bag until the tip flexes down exactly 1/10 of the measured rod length: Above example 9.6″.

3) Remove the plastic bag, paper clip, and the weights you’ve added and weight everything on a gram scale.  Example:  Paper clip, bag, and coins collectively weighed 20 grams.

4) Divide the measured weight by adjusted rod length to get a grams/length ratio.  Match the ratio to the recommended line weight in the table below:  Example 20 grams/9.6″=2.1.  This rod is about a 5 wt. rod.

Ratio            Recommended Line Weight

1.4 – 1.6                              3

1.6 – 1.9                              4

1.9 – 2.2                             5

2.2 – 2.6                            6

2.6 – 3.0                            7

3.0 – 3.5                            8

3.5 – 4.2                            9

4.2 – 5.0                           10

 

 

22 thoughts on “Determining the line weight of a bamboo fly rod.

  1. Thanks for sharing Dave. I guess it is time to do some weighing and measuring. You sure have piqued my curiosity.
    I am going to send this along to some other Rod Makers I know and get their input.

    I’ll let you know how it all turns out.
    Again,
    Thank you

    • Hi Larry,

      I’ve seen a couple different versions of this method over the years but have never tried them until a couple weeks ago. One of the rods I build is a 7′ 9″ 3 wt medium-fast action rod. I’ve always felt it is somewhere between a 3 wt and a 4 wt rod as it handles 4 wt lines very well also. I ran it through this procedure and it came out a 1.6…so there you have it. Let me know how it works for you.

      Dave

  2. This is very similar to the Common Cents system (http://www.common-cents.info/). The “trick” is the empirical database that reflects the amount of deflection to rod weight. I’m curious if the above numbers reflect bamboo rods specifically. The Common Cents database is only graphite rods I believe.

    • Hi Paul,

      Thanks for sharing about the Common Cents system…I ran across it a few years also but never tried it. For fun, I just measured my old Sage 389 SLT (8′ 9″ 3 wt) graphite rod on the method I’ve posted. According to this method, this rod measured out between a 4 wt and a 5 wt rod. So, it might not work that well with Graphite. When it comes down to it, the important thing is matching the right line to our bamboo rods to get the feel and action we’re looking for. To complicate things, plastic line manufactures aren’t all consistent with how they rate the weight of their lines so we just need to try a few to get the right match…as you, Mary Ann, and I have discussed often with our bamboo switch rods.
      Thanks,

      Dave

  3. This makes no sense at all when I tried to use it. Even someone who left a reply that said he came out with a 3.6 so that confirmed his 4 weight line was confused. If he came out with a 3.6 he should have a 8 or 9 weight line. Am I missing something? The other part that is confusing is the distance measured with the weight on the tip. Is that the distance in vertical drop or is it along the curved line? Thanks.

    • Hi Jeff,

      I think you found a typo on a reply of mine….should have been 1.6 rather than 3.6….thanks for pointing that out.

      The distance measured is the vertical drop at the tip-top.

      Hope that helps,

      Dave

  4. I found a very, very old 2-piece Heddon’s bamboo rod that is only 5ft long (total). I ran the experiment above and the ratio is 14, which would be off the charts heavy. Any idea what such a short, stiff bamboo rod would be good for?

    • Hi Keith,

      Thanks for the comment. My best guess….is that you have an old “boat rod” rather than a fly rod since it is only 5 wt long. They have quite long grips and only a couple of guide on them. Most of the old bamboo boat rods I’ve seen have been one piece rods. I don’t believe that Heddon made any fly rods that short in length. Or, if it has a real fly rod grip and appears to be a real fly rod, then it could be that your rod has been altered at some time…like having one section break and turning a 3 piece rod into a 2 piece rod. In any event, I’ve never tried the formula on such a short rod like you’re describing so I’m not sure how well it would apply.

      Dave

  5. Pingback: Old split cane rod - modern fly lines - Fly Fishing Forums

  6. Fascinating bit of smart rule of thumb. IMHO the results read out about .5 wgt
    light on several rods I tried. Orvis 7′ Battenkill, Wright and McGill 3 pc 8′,
    and Gene Edwards impregnated 3 pc 8-1/2′. One of the Edwards tips indicates 4 wgt and the other 5. Still more reliable than shaking and guessing.

    • Hi Fred,

      Thanks for the reply. Yes, I’ve found that this technique isn’t always precise, but it usually get’s you to a good starting point.

      Best Regards,

      Dave

  7. Hi I’m Jake I’m sort of new to fly fishing I got into a couple years ago but anyway I’ve been trying to figure the line weight stuff and just can’t get the hang of it but anyway I was recently given a 9 ft 3 piece south bend bamboo fly rod I put som fly line I had and it just doesn’t cast well so can you tell me what weight line I should use its 9 ft 3 piece and the only markings on it are 9′ and and 57 I would greatly appreciate your help

    • Hi Jake,

      While I’m not a huge collector of old bamboo rods, I can offer up a little advice on your Southbend 57. My understanding is that the Southbend rods with a two digit number designation were in their “Bass Action” series of rods. So, they were faster action and generally heavier rods. I suspect that your rod is probably about a 7 wt rod…probably heavier than what you would be looking for from a standard trout rod. If you’ve been trying to cast the rod with a typical trout line of about a 5 wt and not having much success, I would try it with a heavier line.

      Best of Luck,

      Dave

      • Dave thank you so much I got the 7 wt and It works awsome it’s casts beautifully your responce was greatly appreciated

  8. Just rebuilt a bamboo Montigue/Foothills, for my grandson. 101 inches, came out 4.5 wht. Now i understand why the 4wt line i out on his reel didn’t cast well.. lol.. Thanks..

  9. I know you’ve posted these calculation steps to get the weight of a bamboo fly rod; but I am wondering if the same calculations can be used for other rod materials.

    • I’m guessing that the calculation doesn’t know the composition and should work for any rod whether it be bamboo, glass or graphite.

  10. Hello Dave et al,
    Maybe the most practical solution to this question would be to stringing up a rod in question with various line weights 3, 4, 5 and casting it. Whichever one does the best and feels right during casting would be demonstrate the correct line weight for the rod? It looks line science is getting in the way to practicality.
    Your response is welcome.

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