Just a quick question. I'm getting ready to order some spinning guides for a build i'm doing. My question is how do you measure a guide? Do you measure the frame or the ring ? And do you measure the ID or OD? I guess my one question has two parts. Hope someone can help. Thanks muck, Jack

You measure the OD of the ceramic ring or the ID of the metal ring that holds it ... whichever way you choose to look at it.

Hi Jack,

The guide size is actually the ID of the frame, not including the insert. So the insert will make the 25mm size guide slightly smaller than that. There is some variation in size depending on the type of insert. The Pac Bay minima guides are closest to size, as this insert is very thin. The inexpensive aluminum oxide inserts are thicker and will take up a little more of the ID.

A comparison of a generic size 20 spinning guide and Fuji Alconite guide yielded an actual ID of 17 1/2 mm for the generic guide and 19 mm for the Fuji guide. Cheap guides will generally (not always) have heavier, thicker inserts. Minima's are relatively inexpensive but are the thinnest insert.

Hope this helps.

Terry

Thanks both Terry and Jim, your answers are very helpful and cleared up the confusion. Thanks again. Jack

Jack,
There are some variations in the size of the guides by manufacturer. They are close to the same size, but not necessarily exactly the same size.
So, when you speak of a specific size on a guide, be sure to mention the manufacturer as well as the style guide.

Be safe
Roger

Jack,
When I am measuring guides and or need to verify a specific guide for setup, I use a tapered rod - that has a taper of enough difference to be able to cover the various size guides in question.

I have about three different tapered rods - of different sizes. This allows me to cover the full gamut, of spinning and casting guides - from the smallest to the largest.

Basically, the same principle as a ring sizer that is used by jewelers to determine the size of a specific ring.

Be safe
REW