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  1. #1
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    how are mtb stem angles measured?

    For this stem:

    Race Face Evolve Am Stem at JensonUSA.com

    it says 82/98 degree. The midpoint of those angles is 90 degrees. For a road stem, 72 -73 degrees is considered level. So for a road bike a 6 degree rise stem would be 78-79 degrees. If an mtb stem's reference point is 90 degrees = 0, then a 90 degree stem already angles upward, correct? So a 6 degree stem really angles up? And a 10 degree stem points almost straight up?

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    Quote Originally Posted by happyriding View Post
    For this stem:

    Race Face Evolve Am Stem at JensonUSA.com

    it says 82/98 degree. The midpoint of those angles is 90 degrees. For a road stem, 72 -73 degrees is considered level. So for a road bike a 6 degree rise stem would be 78-79 degrees. If an mtb stem's reference point is 90 degrees = 0, then a 90 degree stem already angles upward, correct? So a 6 degree stem really angles up? And a 10 degree stem points almost straight up?
    No. Six and 10 degree stems are still angled up just slightly. Considered low rise stems.

    Some companies give the stem extension angle relative to the steerer, some as a rise angle: 90 degree angle = 0 degree rise.

    The Race Face is a +/-8 degree rise.

    Traditionally, road stems have a -17 degree rise.

    Final functional rise when installed depends on the frame's head tube angle, even on a road bike.
    Last edited by shiggy; 09-24-2011 at 11:44 AM.
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  3. #3
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    Hey shiggy, what would be a good way to find the measurements of my stem? It is made by norco and is unlisted

  4. #4
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    My observation is that 90 degree stems are normally perpendicular to the steer tube, so yes they angle up a bit. An 82/98 stem is more typically listed as a +/- 8 degree.

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    Quote Originally Posted by ehigh View Post
    Hey shiggy, what would be a good way to find the measurements of my stem? It is made by norco and is unlisted
    A ruler and a bit of trigonometry?

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    No. Six and 10 degree stems are still angled up just slightly.
    Thanks for the info...but I can't agree with your characterization. A 90 degree stem already angles up--and by more than what I would call 'slightly', because the head tube angles are slacker on mtbs. So 6 more degrees angles up a lot in my opinion, and a 10 degree stem is a smoke stack!

    My observation is that 90 degree stems are normally perpendicular to the steer tube,
    Yes, thanks.

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    Quote Originally Posted by happyriding View Post
    Thanks for the info...but I can't agree with your characterization. A 90 degree stem already angles up--and by more than what I would call 'slightly', because the head tube angles are slacker on mtbs. So 6 more degrees angles up a lot in my opinion, and a 10 degree stem is a smoke stack!


    Yes, thanks.
    Like it or not, 5-10 degree stems are low rise in the mtb world. 40 degree is a high rise stem. You can flip one of the later if you really are bothered by your stem angling upward.
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  8. #8
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    If the HA is 0 degrees, then a 0 degree stem would stick out exactly level. The math goes from there.

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    Quote Originally Posted by bing! View Post
    If the HA is 0 degrees, then a 0 degree stem would stick out exactly level. The math goes from there.
    If the HTA was 90 degrees that would be true. A zero degree HTA would be parallel to the ground.

    A stem with an extension perpendicular to the HTA can be called 90 or 0 degree.
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  10. #10
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    Quote Originally Posted by happyriding View Post
    Thanks for the info...but I can't agree with your characterization. A 90 degree stem already angles up--and by more than what I would call 'slightly', because the head tube angles are slacker on mtbs. So 6 more degrees angles up a lot in my opinion, and a 10 degree stem is a smoke stack!


    Yes, thanks.
    You might imagine 5 or 10 degrees is a steep rise, but it really isn't. On my bikes, you see the Truvative +/- 5 stem in the minus 5 position. The white stem on the blue Santa Cruz is a plus 5 degree stem. The Titec stem on the red Jamis I think is plus 10 degrees, and it probably looks like more rise than it is because it is a long 120mm stem.
    Attached Thumbnails Attached Thumbnails how are mtb stem angles measured?-stem-5.jpg  

    how are mtb stem angles measured?-stem-plus-5.jpg  

    how are mtb stem angles measured?-stem-plus-10.jpg  


  11. #11
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    Quote Originally Posted by shiggy View Post
    Like it or not, 5-10 degree stems are low rise in the mtb world.
    Fair enough.

    40 degree is a high rise stem.
    Wow! What is that used for?


    You can flip one of the later if you really are bothered by your stem angling upward.
    No, no. I'm tall and not very flexible. On my road bike, my bars are level with the saddle, so I'm trying to get my bars up. I bought a 6 degree stem, and I was wondering if I need a 10 degree stem, but now I think I might be all right. I'm trying to get my bars level with the seat, but with sag maybe a little lower?

    I have a 160mm Talas fork, and some 750mm ODI Flight Control bars, which I believe have a 25mm/1inch rise. The frame is a Santa Cruz Blur LT2. What do you think? Will that fork/stem/bar combo do the trick? Or, will I need a bunch of spacers under the stem? Is there a limit to how many spacers you can put under a stem?

  12. #12
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    Quote Originally Posted by happyriding View Post
    Fair enough.


    Wow! What is that used for?



    No, no. I'm tall and not very flexible. On my road bike, my bars are level with the saddle, so I'm trying to get my bars up. I bought a 6 degree stem, and I was wondering if I need a 10 degree stem, but now I think I might be all right. I'm trying to get my bars level with the seat, but with sag maybe a little lower?

    I have a 160mm Talas fork, and some 750mm ODI Flight Control bars, which I believe have a 25mm/1inch rise. The frame is a Santa Cruz Blur LT2. What do you think? Will that fork/stem/bar combo do the trick? Or, will I need a bunch of spacers under the stem? Is there a limit to how many spacers you can put under a stem?
    I run the tops of my off road dropbars about level with the saddle, which usually requires a 35-40 degree stem on a production mtb frame. And I prefer using riser stems the spacers under the stem.

    Stem rise (and length) is all about getting the bars where you need them.

    Stating stem size by the extension length andangle is not really very useful as it tells you little about where the bars end up. Take two 100mm stems, one zero degree and one 10 degree. The latter raises the bars, but it also has a shorter functional reach.
    Or compare two 10 degree stems, 80mm and 100mm extensions. The longer stem also places the bar higher.
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    Thanks for all the responses. I put the steerer of my Fox Talas 36 1 1/8" through the head tube of my XL Santa Cruz Blur LT2, then I added the headset pieces, and on top of that I added 30mm of spacers, which the Fox manual says is the maximum. Then I set the center-of-bottom-bracket to top-of-saddle height to the same height as my road bike, and I eyeballed where my 6 degree, 90mm stem and 25 mm riser bars would put the grips, and I think I'm still 3-6cm below my saddle height. I spent two hours looking at all the stems at JensonUSA and Universal, and the only stem I could find with more than 6-8 degree rise was a Ritchey stem with 30 degrees of rise.

    Where are all the 15-45 degree rise stems?

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    Quote Originally Posted by happyriding View Post
    Thanks for all the responses. I put the steerer of my Fox Talas 36 1 1/8" through the head tube of my XL Santa Cruz Blur LT2, then I added the headset pieces, and on top of that I added 30mm of spacers, which the Fox manual says is the maximum. Then I set the center-of-bottom-bracket to top-of-saddle height to the same height as my road bike, and I eyeballed where my 6 degree, 90mm stem and 25 mm riser bars would put the grips, and I think I'm still 3-6cm below my saddle height. I spent two hours looking at all the stems at JensonUSA and Universal, and the only stem I could find with more than 6-8 degree rise was a Ritchey stem with 30 degrees of rise.

    Where are all the 15-45 degree rise stems?
    Thomson does 15*

    Dimension has 105* (15*) and 125* (35*) Dimension 25.4 - AEBike.com

    Salsa 15 and 25 Salsa Stems - AEBike.com

    You could also get a bar with more rise.
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  15. #15
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    If all you need is another 6mm height and you have room under the stem, just add another spacer. 30mm max is not an absolute. I think 50 mm (2 inches) is fine, and think that is sometimes what is recommended.

    Here's a thread on it

    how many headset spacers is too many?

  16. #16
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    Quote Originally Posted by shiggy View Post
    If the HTA was 90 degrees that would be true. A zero degree HTA would be parallel to the ground.

    A stem with an extension perpendicular to the HTA can be called 90 or 0 degree.
    you are correct. my mistake.

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