Stem degree help
Moderator: robbosmans
Guys,
I'm buying a new stem (zipp) and the one it's replacing is a deda, on the deda it says 82 degree, I want the same or slight lower profile for the new one but the ones iv seen online say 17 degree's or 6 degrees, I don't understand why the degrees are so different?
Can anyone help on what I should be buying in the zipp stems?
I'm buying a new stem (zipp) and the one it's replacing is a deda, on the deda it says 82 degree, I want the same or slight lower profile for the new one but the ones iv seen online say 17 degree's or 6 degrees, I don't understand why the degrees are so different?
Can anyone help on what I should be buying in the zipp stems?
Last edited by Wonderman on Mon Aug 31, 2015 4:39 pm, edited 1 time in total.
82 degrees means -8 degrees. Deda counts from 90 degrees. Other brands call 90 degrees 0 degree.
That means -6 degrees is a more upright position compared to 82 degrees.
That means -6 degrees is a more upright position compared to 82 degrees.
Last edited by fEichert on Mon Aug 31, 2015 2:23 pm, edited 1 time in total.
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i think you subtract 90 degree from the 82 and you get 8 degrees. 6 degrees is typical, like an Enve stem. 17 degree is extreme (up or down depending on how you orient the stem).
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It depends on how the angle is measured. 82 degrees is "equivalent" to 8 degrees, 17 to 73 and 6 to 84 (they always sum up to 90).
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Your Deda is an 82 degree (or 8 degree depending how you look at it), therefore neither of those Zipp stems will be the same angle.
you could get the 6 degree and drop it a few millimeters
find a different 8 degree stem
or just deal with a slightly different position
using basic geometric principals (triangles and sine, cosine, tangent) you can calculate the difference in position between differing stem angles
For Example: assuming a 100mm stem the effective position for each angle is as follows
Reach: (stem length)*cos(angle)
Drop: (stem length)*sin(angle)
6 degree:
Reach: 99.45 mm
Drop: 10.45 mm
8 degree
Reach: 99.03 mm
Drop: 13.92 mm
17 Degree:
Reach: 95.63
Drop: 29.24 mm
This is all relative with assumptions taken into account so don't quote me on these numbers, but its a simple enough method to figure out which stem to get.
you could get the 6 degree and drop it a few millimeters
find a different 8 degree stem
or just deal with a slightly different position
using basic geometric principals (triangles and sine, cosine, tangent) you can calculate the difference in position between differing stem angles
For Example: assuming a 100mm stem the effective position for each angle is as follows
Reach: (stem length)*cos(angle)
Drop: (stem length)*sin(angle)
6 degree:
Reach: 99.45 mm
Drop: 10.45 mm
8 degree
Reach: 99.03 mm
Drop: 13.92 mm
17 Degree:
Reach: 95.63
Drop: 29.24 mm
This is all relative with assumptions taken into account so don't quote me on these numbers, but its a simple enough method to figure out which stem to get.
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This might help visualizing the different height/reach of the two stems http://yojimg.net/bike/web_tools/stem.php
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kode54 wrote:i think you subtract 90 degree from the 82 and you get 8 degrees. 6 degrees is typical, like an Enve stem. 17 degree is extreme (up or down depending on how you orient the stem).
I would hardly call 17 degrees extreme. It results in a stem parallel to the ground, which is how nearly all quill stems were made. It's also arguably the most aesthetic.
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jpanspac wrote:kode54 wrote:i think you subtract 90 degree from the 82 and you get 8 degrees. 6 degrees is typical, like an Enve stem. 17 degree is extreme (up or down depending on how you orient the stem).
I would hardly call 17 degrees extreme. It results in a stem parallel to the ground, which is how nearly all quill stems were made. It's also arguably the most aesthetic.
Only if the head angle is 73 deg......
Multebear wrote:^But isn't the head angle always between 72 and 74 deg on road bikes?
Just being a pedant..... If you have ahead angle of 72 and use a -17 deg stem you will have a stem angle of 1 deg, thus it will not be parallel with a level top tube.....probably nobody will notice 1 deg....
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