i am building a 7 foot spinning rod at the moment using NGC

if the spool diam is 45mm could i get away with a size 20 stripper?

You'd just have to try it and see - the fact is, you can get away with just about anything depending on how well you want things to work. If you're using very light line then possibly it would be fine, but it would have to be a pretty high guide to work well without being set a very long distance from the reel.

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My test casting using the NGC has shown that the best-sized stripper is slightly more than 50% of the lip size. I built a surf plugging rod recently, and the spool lip was something like 55 mm. Since half that is 27.5, I thought that I would be fine with a 25 stripper, but I was surprised to find that a 30 worked noticeably better during test casting than the 25 did. In a few instances since then, I've found this to be true: where 50% of the spool is between two guide sizes, the larger one tends to cast better.

These have been my results, but as Tom says, let your own actual testing determine the size. Nothing you read in a book or that someone tells you will be as accurate as your own tests.

Tom - you could try a #20 match guide. I have done that on a few rods with a 20, 10 and then #6 flys. This is for light line (6 or 8# mono) or Fireline. Another consideration is lure weight and casting distance required. If you want to pitch a 1/8 oz jig thirty yards on 8# mono, then that is one thing, but if your going to lob a 1/2 oz lure on braid or superline its another.

Line diameter plays a huge role here, lighter line can utilize a smaller ring without penalty, heavier line needs a larger ring.

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i have used a size 16 stripper on a 50mm spool no problems.
the key to the whole thing is the palcement of your stripper.

well it will be used with PE 0.6 line predominantly and even smaller than that. equivalent to approx 3lb fireline. ill test and see i spose.

if it ends up that a 20 works fine is it alright if its like 27 or something inchs from face of the reel?

I usually go a little larger, having come to the same conclusion as Chris did. That said, adjusting the position of the butt guide can play a huge role in location, size and number of control guides before you get to your running guides. You have between 18 and 23 inches to work with according to the NGC, and with fine diameter braided line, it may even be possible to utilize spacing a little outside of that range. What rod is it going on Tom?

my new bream/bass spinning rod :)

GUSA Pioneer PUR70UL 2kg 7 foot
matched to shimano stradic FI 2500

might have to go get a 25 size and compare

I wouldn't want the stripper way out at 27 inches. You're likely to get a lot of line slap at that distance, both on the cast and on the retrieve.

If you are dead set on using a size 20 ring, then make it a very, very high frame so you can get it back towards 20 to 23 inches from the reel spool.

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Tom, I've just strapped my biomaster 2500 to my All Star, which is set up to take my 1000. Butt guide is a size 20, and falls 21 inches from the spool lip. You should be fine with a size 20 high frame anywhere between that and 23 inches, in my opinion. The only thing that would push me to use a 25 is if the line flow coming off the spool was severely choked. Strap them up and test cast to see which serves you best.

Often the larger ring diameter is simply used to get the line path higher and straighter between the reel spool and choker guide. The line will only use a small portion of it anyway.

If higher frames were available, I have no doubt you could get by with a size 20, or even smaller.

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awesoem thanks a heap ted.

i just used 27 as a random figure.

ill try both and see :)

Thanks guys