Measuring a Quill Stem
06-13-09 | 11:14 AM
#1
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From: Columbus, OH
Bikes: A beautiful columbus steel frame, 1986 Schwinn Voyageur touring bike, Currently Undergoing Overhaul
Measuring a Quill Stem
I'm looking at getting a new Nitto Technomic stem. I'm looking to get an extra 1-2 inch (25-50mm) rise. I'll probably be getting new bars also.
Question, how do I measure my current one, is it from the min insertion line to the top?
Question, how do I measure my current one, is it from the min insertion line to the top?
06-13-09 | 03:14 PM
#2
Senior Member
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From: Québec, Québec, Canada
Bikes: Fuji Touring 64cm, Peugeot Canada PB-18 61cm and winter beaters
Hi,
there are five measurements to fit a quill stem...
1. Stem diameter - that's 22.2mm to fit the inside diameter of 1" (25.4mm) threaded forks. Technomics are only made in that diameter, so are the vast majority of quill stems. There is such a thing as a 25.4mm quill stem made to fit the inside of 1 1/8" threaded forks, but those are rare.
2. Clamp diameter - that's either 25.4mm, 26.0mm, 26.4mm or 31.8mm (rare for quill stems). That's the diameter of the handlebar clamp area. Most MTB handlebars have a 25.4mm clamp area, most road handlebars have a 26.0mm clamp area. 26.4mm is for older Cinelli handlebars, 31.8mm is for "oversized" road and MTB handlebars, but 31.8mm quill stems are quite rare. Technomics come in 25.4mm and 26.0mm clamp size. Some older or cheaper road handlebars have a 25.4mm clamp area.
3. Stem height - that's the height of the stem column. That's from the bottom of the stem, the part that fits inside the stem, all the way down to the expander - all the way to the top of the stem, where the expander bolt head is. The Technomic has a 225mm overall height, and the minimum insert line is a couple cm above that - you can have up to 160mm of stem showing above the minimum insertion line.
4. Stem length (extension) - that's the length of the part of the stem that goes towards the handlebars. It's measured center-to-center, between the middle of the expander bolt head to the middle of the handlebar clamp.
5. Stem angle. That's 72 degrees for a Technomic, which is close to the angle of most road bike headtubes - thus, a 72 degree stem goes forwards towards the handlebars pretty much horizontal. There are different systems of measurement for the angle. Some would call the Technomic a -18 degree stem, as it's 18 degrees of negative rise compared to a square angle of 90 degrees from the column of the stem. A positive rise stem (angle greater than 90 degrees from the stem column) will give you more rise with a shorter stem column.
In order to know the handlebar position a new stem will give you, you need the stem height, length (extension) and angle, and some trigonometry.
there are five measurements to fit a quill stem...
1. Stem diameter - that's 22.2mm to fit the inside diameter of 1" (25.4mm) threaded forks. Technomics are only made in that diameter, so are the vast majority of quill stems. There is such a thing as a 25.4mm quill stem made to fit the inside of 1 1/8" threaded forks, but those are rare.
2. Clamp diameter - that's either 25.4mm, 26.0mm, 26.4mm or 31.8mm (rare for quill stems). That's the diameter of the handlebar clamp area. Most MTB handlebars have a 25.4mm clamp area, most road handlebars have a 26.0mm clamp area. 26.4mm is for older Cinelli handlebars, 31.8mm is for "oversized" road and MTB handlebars, but 31.8mm quill stems are quite rare. Technomics come in 25.4mm and 26.0mm clamp size. Some older or cheaper road handlebars have a 25.4mm clamp area.
3. Stem height - that's the height of the stem column. That's from the bottom of the stem, the part that fits inside the stem, all the way down to the expander - all the way to the top of the stem, where the expander bolt head is. The Technomic has a 225mm overall height, and the minimum insert line is a couple cm above that - you can have up to 160mm of stem showing above the minimum insertion line.
4. Stem length (extension) - that's the length of the part of the stem that goes towards the handlebars. It's measured center-to-center, between the middle of the expander bolt head to the middle of the handlebar clamp.
5. Stem angle. That's 72 degrees for a Technomic, which is close to the angle of most road bike headtubes - thus, a 72 degree stem goes forwards towards the handlebars pretty much horizontal. There are different systems of measurement for the angle. Some would call the Technomic a -18 degree stem, as it's 18 degrees of negative rise compared to a square angle of 90 degrees from the column of the stem. A positive rise stem (angle greater than 90 degrees from the stem column) will give you more rise with a shorter stem column.
In order to know the handlebar position a new stem will give you, you need the stem height, length (extension) and angle, and some trigonometry.
