Re: [CR] Measuring Stem Extension Illustration (Nitto & others)

(Example: Racing:Jean Robic)

In-Reply-To: <481770.40266.qm@web84002.mail.mud.yahoo.com>
References: <481770.40266.qm@web84002.mail.mud.yahoo.com>
Date: Sun, 2 Jan 2011 05:17:49 -0500
From: "Ken Freeman" <kenfreeman096@gmail.com>
To: Andrew Gillis <apgmaa@verizon.net>
Cc: classic rendezvous <classicrendezvous@bikelist.org>
Subject: Re: [CR] Measuring Stem Extension Illustration (Nitto & others)


Andy, I have the same Pearl box, and it agrees with how my Pearl 12 (what came in the box) measures - 120 mm.

I found a Cinelli 1A marked "130" measures the same as the Pearl 12, if measured the same way. The Cinelli, if measuered from the draw bolt center to the center of the bar clamp along the top of the extension, measures 130 mm. So at least for that one, the "test" seems to be to stand above the bike and measure as just stated.

But the previous thread seems to say that not all Nittos, Cinellis, or 3TTTs seem to measure "correctly" (does this mean "as marked?") using the same technique. In other words if the measurements of the previous thread were done correctly, there is not consistency of measurement technique within brands or perhaps even with models of stem.

This confused situation cries out for an independent standard of measuring, so that at least we hobbyists who are trying to self-adjust our bike fit can know when we're buying a new stem that will actually deliver the fit correction we are trying to achieve.

On Sun, Jan 2, 2011 at 4:17 AM, Andrew Gillis <apgmaa@verizon.net> wrote:
> CRs:
>
> Sorry for my previous message, which was incomplete. I hit the send button
> instead of the save button. To repeat:
>
> Bob Hanson's drawing of stem extension measurement
> (http://i32.photobucket.com/albums/d7/k4drd/Bicycles/QuillStem.jpg)
>
> shows a Nitto Technomics stem.
>
> To add further confusion to this stem measurement discussion, I've found a
> sizing difference between various models of Nitto stems:
>
> I've been using a Nitto Pearl13 stem for years. The Nitto Pearl is measured
> in the perpendicular dimension. This was shown in a small picture on the
> side of the blue box in which the stem was shipped. (I discarded the box
> long ago.) Hence, a Nitto Pearl 13, which is specified to measure 130mm at
> 90 degrees (perpendicular to the steering tube), therefore measures about
> 135 mm along the horizontal centerline. My actual, along the side
> centerline measurement was 137mm (another story, see below.)
>
> I needed to reduce my reach by about 5mm, so I purchased both a Nitto
> Technomics (tall quill, approx 190mm) and also a Nitto Technomics SQ (short
> quill, 155mm). Both of these stems measure 130 mm along the side centerline
> of the horizontal part of the stem. These stems were in sealed bags without
> any documentation. These two Technomic (standard) stems are obviously
> about 5mm shorter than the Pearl 13, despite being the "same" size.
>
> I've similarly found slight differences (about 3mm) in sizing for between
> the 3T Record 84 vs. 3T Status quill stems. I recall that the difference was
> about 3mm, with the Status being longer.
>
> A Special Note: The Nitto Pearl 13 stem extension angle is approximately 72
> degrees. Conesequently, the "horizontal" top part of the stem slopes down
> instead of being parallel to the top tube of my Richard Sachs bike, which
> has a 74 degree head angle. If I do some number crunching (high school
> trigonometry) I get 135mm along the free-space horizontal measurement, and
> about 137mm along the horizontal centerline of the stem.
>
> Measure consistently!
>
> Andrew Gillis
> Pending Rain in Long Beach, CA
>
> _______________________________________________
>

--
Ken Freeman
Ann Arbor, MI USA