I notice that fly lines are all about the same diameter, within a few thousandths of an inch, yet fly guides are offered in many quite different sizes. And it seems that the lighter weight rods get the smaller guides, and the heavier weight rods get the bigger ones. I can see why one wouldn't want any extra weight on the rod, especially the lighter power rods, but why are so many sizes needed? It can't be because of the different diameters of the fly lines, can it? Is there a recommended size for each weight fly rod? I'm talking the running guides, not the stripper.

Michael
In fact - fly line diameters do vary drastically. A Skagit floater flyline, for instance, is rope-like.
Also - personal preference plays a part.
Some OEM's use different guides for saltwater vs fresh.
Sage used to make a rod for saltwater whose runners were oversized. A marketing issue.
Some builders like a knot in a flyline to be able to clear all guides and the tip-top. So they will install up-sized guides.
Some builders don't subscribe to RB.Org's opinion that only one size runner is needed. Some will use graduated guide sizes.
regards,
Herb

Many different sizes aren't needed for the most part. Although, depending on what connections you may need to pass you can't expect to use the same size guides on a rod running a loop to loop shooting head against the same weight rod running a standard WF or DT line.

The reason you don't need a lot of different sizes on a fly rod is because you simply don't. Trying to supposedly gradually reduce line angle by using several different sized guides become apparent if you actually take the time to measure the reduction height/angle. The difference in moving to say a #10 to a #3 snake, versus to a #1 snake, is less than 1/10th of a millimeter. It's almost silly how unnecessary using so many different sizes is against the distance between those guides.

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Multiple guide sizes are just one area of form versus function in rod building, along with large, decorative thread wraps, coats of epoxy and paint on rod blanks, and various other decorations. Some people are willing to sacrifice rod performance to rod appearance, some are not. These differences in opinion keep rod builders in business.

The large to small guide train, is a traditional way of doing the build. Basically a "cone" theory. In recent times it has been proven that it provides no real benefit. Do to the way a fly is cast, in most cases the line is not running out through the guides as it is already out the tip. The exception is when one is shooting line for extended casts.

Guides come into play when fighting and landing a fish, again the cone theory provides no benefit! Spacing is important here!

As mentioned above, the guides need to be of a sufficient size to allow passage of the knots being used, but no larger.

An adjunct to the size discussion, would be the subject of single foot vs double.

I believe originally they were using such large ring sizes that a graduated (cone) system cut down on the weight especially near the tip. Now we are using smaller guides and even "micro" guides and that is not an issue so much. On fly rods snake guides are so light that using the same size in the running train is not an issue. It appears we have made it less complicated and are getting better results with fewer guide sizes. My belief (casting / spinning) is to keep the line as straight as possible coming from the reel to the stripper to the tip or smallest guide on the running train and you can usually do that with 3 or 4 different sizes and sometimes 2 on a casting rod.

As to guide spacing determining the arc of a rod: 1) firmly attach a rod at a 45 degree angle parallel to and close to a wall 2) tie a weight heavy enough to bend the rod tip down two feet or so to the rod's tip top. 3) trace the curve of the rod blank lightly with a pencil on the wall. 4) attach a reel to the blank, run the line through the guide train and tip-top, tie the line to weight you used before, suspend it as you did before, and trace it as you did before. Compare the two tracings. Any conclusion you can draw?

Phil, I respectfully ask, what is your point relative to the original post? I so far have missed it.

Phil, I am missing your point completly!

Michael: The point is the guide train does not change the arc of the rod except for a tiny increase in stiffness due to the guide feet - and you can prove it to yourself with those four steps. Put your guides wherever you want. You won't change the arc of the rod enough to notice. One tip top guide or tip top plus three guides, or nine guides, the rods arc under the same load will not change appreciably. Guide placement does not determine the arc of the rod. Guides keep your line from flopping around the rod blank



Edited 1 time(s). Last edit at 05/20/2020 08:28AM by Phil Ewanicki.

Guides do not make a rod stiffer - they make it softer. Measure the ERN and/or CCF of the bare blank. Wrap a bunch of guides along its length and measure it again. The rod will be less powerful (softer) and exhibit much slower speed. In fact, you don't even need to measure it - guides soften a rod by enough that you can feel it in the hand.

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Phil Ewanicki Wrote:
-------------------------------------------------------
> Michael: The point is the guide train does not
> change the arc of the rod except for a tiny
> increase in stiffness due to the guide feet - and
> you can prove it to yourself with those four
> steps. Put your guides wherever you want. You
> won't change the arc of the rod enough to notice.
> One tip top guide or tip top plus three guides, or
> nine guides, the rods arc under the same load will
> not change appreciably. Guide placement does not
> determine the arc of the rod. Guides keep your
> line from flopping around the rod blank

I have to strongly disagree with this. Take two identical blanks and match the guides on one to the natural flex curve of the rod, which I what I think you mean by arc, and on the other just stick 3 or 4 guides somewhere along the blank. Now run a line through the guides and load it. The one with just a few guides will indeed flex differently than the one with more guides. It will have severe flex between each pair of guides and can even put the rod in danger of breaking between a pair of guides. This is why when you do a stress dist. test you load the rod tip, not the line running through the guides. This way the blank takes its natural bend and you then match the guides to that natural bend.

Michael: I have always built rods with widely spaced guides near the butt and more closely spaced guides at the tip, You predict this would result in a rod with "severe flex" at the butt and presumably less flex at the tip?! The presence or absence of guides will make just a tiny difference in the ARC of the blank, although the weight of the guide train WILL have a significant impact upon the recovery speed of the blank. It's good idea to have the line parallel the curve of the blank and proper guide placement is necessary to do this. However, when stressed at the tip the BLANK will always assume its natural curve, unless you smother it with loads of guides, wraps, and ferrules. The construction of the blank alone determines the "natural flex curve" of the blank; the leveraged weight of the guides, thread winding, paint, epoxy, hook keepers, etc. slow the action of the rod to a FAR greater extent than they change its natural bend.

Action is where the rod initially flexes. Speed is how fast it reacts and recovers.

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Thanks for reminding me (again) Tom. What I'm trying to say is guide placement does not change the action of a rod - how it flexes, but does change the speed of a rod due to leveraged weight.