Rod bend vs rod unload

[Walter]

This goes out on a tangent but it occurs to me that when people have a physical issue from casting such as tendinitis or rotator cuff injury and want to keep casting but reduce stress what sort of advice should we be giving on rod selection?

The “conventional wisdom” says shorter, lighter and softer. The first two reduce torque applied by the caster. That has to be good. But the third one???

Would it depend on nature of injury because the stop might be more stressful than the stroke in some cases and the other way around in others?

Not suggesting we should be providing medical advice but when helping with healing waters one of the rules we used was that we should first seek to do no harm.

[Paul Arden]

I would argue that action is more important than stiffness although there is certainly a connection. I think it is jarring when we use a rod with a very stiff lower half. This means that we need to initially stop more of the lever from the get-go. Tennis Elbow territory. I’ve certainly had it as a result.

Cheers, Paul

[Walter]

Paul,

Yeah, I think you’re right there. Shock is the issue and the shock comes from the stop. I’ve taught students that are having issues, including myself at times, to think of rod unloading with follow through rather than making a hard stop. Slow down the rod at the point where you want the rod to unload so the loop forms and then follow through allowing the rod and hand to coast to a stop rather than the hard stop. The loop is still kept tight by raising the hand to keep the tip path fairly straight.cuts down on counterflex and rebound too.

Not exactly the best distance method but they wanted to go fishing without the pain. I can say that from experience it is less painful.

[Paul Arden]

I honestly think this trend to stiff butt / very pronounced tip action rods, that you see from many manufacturers is a design flaw. Not only does it make long range Accuracy difficult (the feel doesn’t change after about 70’) but it gives tennis elbow. In this regards it’s a tackle problem not a technique problem. Just because a rod flexes into the handle doesn’t mean it has to be slow.

Apart from that I don’t know if rod action affects other parts of the body. Generally if I have a student who has an old injury we try to carefully find methods of moving that don’t cause pain. That really becomes a bit of an exploration. I’m not a fan in general of the Oval Cast/ Lefty’s Cast (principally because of tracking) but there sure are times when it’s better for the student.

Cheers, Paul

[Walter]

Definitely moved out of physics realm but thanks for responding. If I want to talk about it more I’ll move the question to another area.

[Lasse Karlsson]

I honestly think this trend to stiff butt / very pronounced tip action rods, that you see from many manufacturers is a design flaw. Not only does it make long range Accuracy difficult (the feel doesn’t change after about 70’) but it gives tennis elbow. In this regards it’s a tackle problem not a technique problem. Just because a rod flexes into the handle doesn’t mean it has to be slow.

Cheers, Paul

All rods flex into the handle?

And who is in on that particular trend? Have to ask, haven't bought a new rod i 10 years, so not up to date on those things, the students that comes with new rods all have quite flexible stuff.

Cheers
Lasse

[Paul Arden]

There are degrees of flexibility. I know that the TCR for example bends down to the cork but that’s the one that gave me TE. Or maybe it was TCX. What I suspect, is that being the market leader in the premium end, they have been closely copied. Even stuff coming out of the Far East can have this stiffer lower section. Contrasted to rods of 30 years ago this is quite different. IMX/Alpha/XP.

Torsten won’t like the fact that the topic has moved away from physics!

Cheers, Paul

[Walter]

Probably time to rename it anyway. Seems to have run its course.

[Torsten]

Hi,

The difference is one of definitions. Work and force are not the same thing. (@Torsten - there's something else for the glossary.)

Yup, added, like some other terms as well.

--

Walter:

People have asked how many casts are enough. I’ve always been partial to a chebyshev analysis for that. You could plug numbers in as you take them and keep going until you are satisfied with the confidence interval it generates but I expect 10 casts per rod would be enough. Perhaps only 6.

I think that depends on the question, and properties like standard deviation and the confidence interval - but I think I need to refresh my knowledge.

You can find some sample size calculators on the web, like this one:

Let's say we want to compare two rods / two (distance) means:
If we assume that there is only a small difference e.g. 1m and a standard deviation of 2m (compare the results of the 8x8 study), I'm getting this result:

https://statulator.com/SampleSize/ss2M.html

"Assuming a pooled standard deviation of 2 units, the study would require a sample size of:

63

for each group (i.e. a total sample size of 126, assuming equal group sizes), to achieve a power of 80% and a level of significance of 5% (two sided), for detecting a true difference in means between the test and the reference group of 1 units.

In other words, if you select a random sample of 63 from each population, and determine that the difference in the two means is 1 units, and the pooled standard deviation is 2 units, you would have 80% power to declare that the two groups have significantly different means, i.e. a two sided p-value of less than 0.05."

(we can play with the values there)

Greetings,
Torsten

[Paul Arden]

While I agree that that would be an interesting experiment there is a factor to be taken into account which is Lasse’s argument that you are “best with what you practise”. Now this was definitely not the case for me in our little experiment in Scotland, but it should be taken into account because I think there is a ring of truth to it. Which makes life more difficult.

An example of this I can draw from bike fit. If I move the saddle up or down it feels strange. I only really know if it’s been successful or not a few weeks later.

Similarly back to fly casting, when I make an adjustment to my stroke it again feels strange. Only 3-4 weeks later will know if it’s a good change or a poor change.

Factor that into rod selection and it’s a long term game. If I for example pick up a 12WT rod and start practising with that, perhaps my distance will initially fall. But three weeks later it may pass the 10WT that I currently use. (I hope not!).

Anyway it’s all interesting and gives us something to play with. When we used to do the Sexyloops shootouts we used to cast all sorts of “mismatched” tackle. Some of it was absolutely dreadful. But what I did take away from that is that it is the flyline and not the rod that is more important. And of course it is the driver that is most important of all.

Cheers, Paul