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  1. #1
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    riser bar vs. higher rise stem

    I flunked geometry class and need a little help. On a 2006 Scalpel, what would be the difference on bar height (distance from ground) and stem length (distance from center of Lefty clamp parallel to the ground) between a 1.5" riser or 3/4" riser bar (EC90) and 5 degree or 20 degree stem rise. I am deciding on which XC3 stem/steerer to buy and new bars.

    Thanks

  2. #2
    Nightriding rules SuperModerator
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    you also need to factor the stem length

  3. #3
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    I went through the same thing recently. The rise is the SIN of the angle times the stem length i.e. Sin (5 deg) * 100mm. For 5 and 20 degrees, to get the rise, mutiply the stem length by 0.087 and 0.342 respectively. I have a 120mm 5 deg stem on my prophet. I kept the stem and bought a 2.25" rise DH bar.

  4. #4
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    Here's what I did. Its a lot easier to do than write.
    Take a sheet of lined A4 paper (check lines are 1cm apart). From the right hand side count down 18 lines. Then measure back 18cm to the left along that 18th line. Thats your reference point. A line back to your start point is 45degs and every 2 lines down reduces the rise by 5 degs. You've got a scale drawing and can draw any angle you want. You need to measure stem length along the hypotenuse (sloping line). You can easily compare the differences between combos of stem length, rise and bar rise. Good luck!

  5. #5
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    Quote Originally Posted by Baker921
    Here's what I did. Its a lot easier to do than write.
    Take a sheet of lined A4 paper (check lines are 1cm apart). From the right hand side count down 18 lines. Then measure back 18cm to the left along that 18th line. Thats your reference point. A line back to your start point is 45degs and every 2 lines down reduces the rise by 5 degs. You've got a scale drawing and can draw any angle you want. You need to measure stem length along the hypotenuse (sloping line). You can easily compare the differences between combos of stem length, rise and bar rise. Good luck!
    Cool, that sounded hard but worked great.

    So from my calculations going from a stem of (100mm / 5 degrees) to (90mm / 20 degrees) will give me about 1 inch of height and make the bar about 3/4 of an inch closer.

    Thanks for the help.

  6. #6
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    Don't forget fork angle!
    This will factor into it all as the calculations you have just spoken about are in context to the angle of the fork not vertical!
    This makes quite a bit of difference
    Your vertical change would be 1"xsin (HA)-0.75"xcos(HA)
    Horizontal "1xcos(HA)+0.75"sin(HA)

  7. #7
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    I can't check your maths but you make a good point. You can make the adjustment visually though by tilting your piece of paper to match your head angle. Probably easier than the maths for some of us.

  8. #8
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    Yep that works just as well

  9. #9
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    jekyllrider, this might help you, I just bought a (20 degree 90mm) stem to replace the stock (5 degree 100mm) stem. this is what they look like side by side. I'm probably going to get riser bars too cause I want the bars higher, however I'm still glad I got the stem.




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