Stem degree help

Discuss light weight issues concerning road bikes & parts.
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Wonderman
Posts: 121
Joined: Tue Sep 18, 2012 9:17 am

by Wonderman

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?
Last edited by Wonderman on Mon Aug 31, 2015 4:39 pm, edited 1 time in total.

fEichert
Posts: 16
Joined: Tue May 26, 2015 6:27 am

by fEichert

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.
Last edited by fEichert on Mon Aug 31, 2015 2:23 pm, edited 1 time in total.

kode54
Posts: 1184
Joined: Tue May 23, 2006 9:39 pm

by kode54

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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Lightweenie
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Joined: Sun Aug 03, 2014 1:00 pm

by Lightweenie

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).

wpccrunner
in the industry
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Location: North Carolina

by wpccrunner

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.

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Wonderman
Posts: 121
Joined: Tue Sep 18, 2012 9:17 am

by Wonderman

Guys thanks so much for the quick and detailed responses,

I'm taking as I want either a 8degree stem for the same position or maybe 9/10 degrees for a slightly lower one.

Cheers again

fogman
Posts: 779
Joined: Fri Oct 30, 2009 10:36 pm

by fogman

With a 110mm length stem, every degree of stem angle adds approximately 2mm of handlebar height.
It's all downhill from here, except for the uphills.

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ALAN Carbon+
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Joined: Mon Dec 26, 2005 9:21 am
Location: Canberra, Australia

by ALAN Carbon+

This might help visualizing the different height/reach of the two stems http://yojimg.net/bike/web_tools/stem.php

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jpanspac
Posts: 160
Joined: Thu Apr 11, 2013 8:21 pm

by jpanspac

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.
My favorite components are the ones I never have to think about.

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corky
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Location: The Surrey Hills

by corky

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
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Joined: Sat May 02, 2015 10:11 pm

by Multebear

^But isn't the head angle always between 72 and 74 deg on road bikes?

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corky
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Location: The Surrey Hills

by corky

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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