Quill measurements

[Boothy]

I'm sure this is page 1 for most of you boys, but I've never really meddled with Quill stems before.

I have an old GT which currently has a 25.4 quill stem, which I thought was a 1", but I just bought another stem from fleabay which says it is 1" but it only measures 22.2.

I know 1" = 25.4, but is it the actual quill or the steerer tube i should be measuring?

Might sound stupid, probably is... I just cant figure why the 22.2 is advertised as 1"?

Thanks you heros.

(And if anyone has a 25.4 quill they want rid of let me know!)

Boothy

 

[one-eyed_jim]

Quill diameters are normally 1/8" smaller than the external diameter of the steerer, so a 1" steerer takes a 7/8" (22.2mm) quill, a 1 1/8" steerer takes a 1" (25.4mm) quill, and a 1 1/4" steerer takes a 1 1/8" (28.6mm) quill.

The confusing part is that it's common to refer to stems and headsets according to the external diameter of the steerer they fit, so a quill stem that measures 22.2mm (7/8") is often referred to as a 1" stem, a quill stem that measures 25.4mm (1") is often referred to as a 1 1/8" stem, etc.

If in doubt, it's always best to double check.

 

[one-eyed_jim]

Here's BikePro on the subject:

As headsets come in three sizes, so must the stem's quill diameter to fit them. The size is actually the outer dimension of the fork steerer tube, but for both fork, headset, and stem, it is referred to as 1", 1 1/8" or 1 1/4". If you actually measure the quill that fits into the 1" fork, and headset, you will find that it's really 7/8" (22.2mm), not 1" (25.4mm). The 1 1/8" quill is really just 1" (25.4mm) in diameter. The 1 1/4" quill measures out to be 1 1/8" or 28.6mm. Again the stem, headset, and fork are all referenced using the matching forks steerer tube outer diameter.

http://www.bikepro.com/products/stems/stemover.html

and here's Sheldon:

If your bike has a traditional threaded fork/headset, your stem will be sized to fit inside of the steerer. This sometimes causes confusion because the nominal size is based on the outside diameter of the steerer, but the diameter of the stem is 1/8" smaller to fit _inside_ the steerer. Thus, a normal 1 inch fork requires a stem of 7/8" (22.2 mm) diameter, while a 1 1/8" fork requires a stem 1 inch in diameter. Thus, depending on how you look at it, either of these stem sizes might be referred to as "1 inch." If your bike uses a threadless headset, there's less confusion, because the stem fits the outside of the steerer, just like the headset.

http://www.sheldonbrown.com/handsup.htm ... patibility

 

[one-eyed_jim]

I'll add that it's more common to see the quill diameter given as a metric decimal, and the nominal size (external steerer diameter) as an inch fraction.

i.e. 22.2mm, 25.4mm and 28.6mm will nearly always refer to the measured diameter of the quill, while 1", 1 1/8", 1 1/4" refer to the external diameter of the corresponding compatible steerer.

Clear as mud?

 

[mikee]

so 3 sizes a small one 22 (.2)a middle one 25 (.4)and a big one 28 (.6)

easy

2/4/6

22.2 usually older bikes and steel frames ,early dales too

25.4 most stuff these days

28.6 oddities like alpinestars and other usually ali framed bikes

 

[Boothy]

you absolute gentlemen, that clears it up reet proper for me.

Thanks again,

Boothy.

 

[Boothy]

Incidentally, do you reckon this wee shim would convert a 22.2 quill to a 25.4 quill? Iknow it's not meant to but i can't work out if it would work any way.

Opinions?

Thanks.

http://cgi.ebay.co.uk/System-ex-Stem-Sh ... _542wt_907

 

[Xesh]

That's for the threadless (or aheadset) stems which clamp to the outside of the fork steerer. It'll never fit a quill stem. Besides I'd never use a shim on a quill stem (I just wouldn't trust it to tighten properly) when you can get a complete stem much more easily anyway.