84 dgrees or 7?
Moderator: robbosmans
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+/- 8 aka 82 degrees
+/- 7 aka 83 degrees
For comparing stack and reach, use: http://yojimg.net/bike/web_tools/stem.php
+/- 7 aka 83 degrees
For comparing stack and reach, use: http://yojimg.net/bike/web_tools/stem.php
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It's actually a good question because it's one of few inconsistent ways people list that measurement. For starters, you have a 90 degree stem angle against the steerer tube as a starting point if the stem is dead straight. The 84 or -6, or -7 or -17, etc. is the angle of the stem. Some brands list the 84, others the -6 to indicate the angle, but those would be the same. The +/- indicates that you can flip the stem to have a positive or negative slope, plus is up, negative down.
- de zwarten
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jeza wrote:hi could someone tell me the difference between a stem of 84 degrees and on e of +/- 7 degrees ??? i know i'm being thick but....
good info here:
http://www.habcycles.com/fitting.html
jeza wrote:hi could someone tell me the difference between a stem of 84 degrees and on e of +/- 7 degrees ??? i know i'm being thick but....
Some manufacturers specify angle between fork tube and stem while some specify angle between imaginary line that is perpendicular to the fork tube and stem.
83 deg stem in first case would mean -7 deg stem in the second case. +|- means it can be installed so that the stem is both below or above imaginary perpendicular line.
Even if not noted every stem can be turned to positive or negative angle, worst that can happen is you will have letters upside-down.
So in short 84° is -6° and -7° is 83°. Thats only 1° of difference.
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I believe this is how 17d and 6/7d became significant.
When bike only came with level top tubes, stem makers made quill stems with 17d pitch so the stem appeared parallel to the ground and the top tube. 17d is the orthogonal complement to the 73d head tube angle.
With the advent of compact geometry, the top tube sloped by roughly 7d degrees. Stem makers started making stems that complemented the sloping top tube. Stems had 6, 7, 8d pitch. However, racers wanted more drop or others wanted to overcome the taller headtubes. So, the 10d (e.g., Thomson) 17d threadless stem appeared. In my opinion, a sloping top tube frameset with a 17d stem looks odd.
When bike only came with level top tubes, stem makers made quill stems with 17d pitch so the stem appeared parallel to the ground and the top tube. 17d is the orthogonal complement to the 73d head tube angle.
With the advent of compact geometry, the top tube sloped by roughly 7d degrees. Stem makers started making stems that complemented the sloping top tube. Stems had 6, 7, 8d pitch. However, racers wanted more drop or others wanted to overcome the taller headtubes. So, the 10d (e.g., Thomson) 17d threadless stem appeared. In my opinion, a sloping top tube frameset with a 17d stem looks odd.
jeza wrote:hi could someone tell me the difference between a stem of 84 degrees and on e of +/- 7 degrees ??? i know i'm being thick but....
It's 1 degree. To be honest though, variances in stack height and measured vs actual length between different brands and models are often more significant!
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smokva wrote:jeza wrote:Even if not noted every stem can be turned to positive or negative angle, worst that can happen is you will have letters upside-down..
Not always the case but most of the time. Some stems are not designed to be flipped. For example, PRO stems are only -10 due to the puzzle clamp.