I have a (93?) Giant ATX 770 that I'm attempting to convert to a drop bar do-it-all bike. I will need a taller/shorter stem. It came with a Kalloy Uno with 25.4 (1") stamped on it. So I search for a 25.4 quill stem and come up with this:

https://www.bikebling.com/Kalloy-Dirt...loy-al-222.htm

Confusion happens when I read "22.2mm quill O.D.". Is this for a 1" steerer tube? Do I need something for a 1 1/8 (28.6) steerer tube? I was also looking at this fairly ugly thing because I might need a removable face if I want to use the 26mm Cinelli bars I have:

https://www.amazon.com/Profile-Design.../dp/B00361BF40

Would I need the 120 x 40d x 1in or the 120 x 40d x 1 1/8in? Does the last measurement refer to the diameter of the actual quill/expander wedge thing or the steerer tube that it goes into? Am I really stupid?

Do you have a 1" steer tube or 1 1/8"? Is that model equipped with a threaded or threadless headset? If you have a 1" threaded steer tube, you (USUALLY) need a 22.2mm OD stem. Quill stems for 1 1/8" steerers are becoming exceedingly rare, and you might be better off converting to threadless at that point.

A picture of the bike would help immensely.

If the Kalloy Uno doesn't have lots of wiggle room with the expander bolt loose, you have a 1" steerer.

25.4 may very well be refering to the bar clamp diameter.

I like stems like that Dirt Drop but getting some road bars around them can be a PIA. If this is a 1" headset I would use a 1" to 1 1/8" quill adaptor before using that Profile stem.

BikePedia is no help. https://www.bikepedia.com/QuickBike/B...-770&Type=bike

Do you use a 32mm or a 36mm wrench to adjust the HS? 32 is 1" and 36 is 1 1/8"

It is a threaded headset that seems to measure 1" and some change (not quite 1 1/8 I don't think) at the lockring. I haven't taken the fork out to measure the steerer and I haven't had the headset off yet. I don't even have any wrenches that big! I'd say the Uno fits in there pretty snug. I stuck a quill stem (with 22.2 stamped on it) from an old road bike in there and it's loosey goosey. The diameter of the Uno wedge is pretty much right on 1".

I like the looks of the dirt drop too but I'm not sure if I can find one with enough rise though and I really don't think I'll be able to thread the modern 26mm ergo Cinelli drops through it. Perhaps I should either get different bars or go with quill to threadless adapter (if that's an option). Bikepedia needs to have a picture of this bad boy in there in all it's black and pink early 90's glory.

I should probably measure the headset nut/lockring tonight when I get home and that will give me my answer, yeah?

Ah, I was confused by your first link. It appears there is an identical one for 1-1/8" threaded steerers: https://www.niagaracycle.com/product_...ucts_id=421027

You don't need to take your headset completely apart, I think we can be confident your bike isn't a 1" (22.2mm quill) steerer.

That's what it sounds like to me as well. I was just confused by the similar numbers. Thanks for the help everyone. I was going to try to keep this a low budget build modeled after some of the beauties in the "Show Your Vintage MTB Drop Bar Conversions" thread, but I'm realizing that my parts bin is small and so is my toolbox. If I want to use the bars I have, I'll have to go with that Profile stem or something similar with a removable face. I could switch up the bars and have a more traditional looking stem, or I could just get a threadless adaptor if that's even possible. More research!

Ah well, it'll be worth it in the end...if I can make it fit.

BTW, can I even use a 26mm drop bar with a removable face stem even if it says it has a 25.4 clamp diameter?

No. even if it has a removable face the bars still need to be the same diameter as the clamp. You can use a smaller diameter bar but then you need a shim.

I am not sure, they don't show an option for picking either 1" or 1 1/8".

Hmm, perhaps they don't have all of them in stock. I was going by this:

Some MTBs and some older road bikes (notably Schwinns) with 1" headsets had thicker walled steerer tubes than normal and took 21.1mm (.833") diameter quill stem instead of 22.2mm.

Well dang it. I might just look for a 1 1/8 threaded to threadless adapter then. Nashbar has one for cheap.