I'm completely scoobied by stem rise. I searched back through the archives and only got more confused.
So here's my dumb question: my current stem is a little below horizontal. Flipped, it's way over. I'd like to be at or a little above horizontal. There's a nice stem on ebay, a -10 rise. Where will that stem put me?

I'm completely scoobied by stem rise. I searched back through the archives and only got more confused.
So here's my dumb question: my current stem is a little below horizontal. Flipped, it's way over. I'd like to be at or a little above horizontal. There's a nice stem on ebay, a -10 rise. Where will that stem put me?

If currently your stem is below H, then you have a -17 or so. Generally, your HT will be 74. Definitely will rise alot if you flip it.

So, a -10 will be slightly above horizontal. I use a slight positive rise on a Thomson +5. So, a zero would be perpendicular to the steer tube, and would rise at the angle of the HT.

Here is the explanation I found in some thread somewhere. First the variables are explained, then the formulas, then examples... It helped me a lot to draw pictures to better understand what was happening. This is cut and pasted from an email to a friend... thats why the examples arent actually what you asked about...


SA = stem angle
--> e.g +/- 7deg = 83/97 degree
--> e.g. +/- 17deg = 73/107 degree
--> depends on whether the stem is "upside-down" or not.
--> can be measured if you have the right tools. or look it up online

HTA = head tube angle = determined by the frame of you bike, cannot be changed
--> a Trek 1500 in size 52 has a HTA of 71.5 degrees
--> a Lemond BA in size 55 has a HTA of 73.5 degrees

L = stem length = measured from center to center of clamps along the
side of the stem

Formulas:
(SA-HTA) = #
horizontal distance = COS(#)x(L)
verticle rise = SIN(#)x(L)


e.g.

(a)
--> 97deg - 71.5deg = 25.5deg
--> COS(25.5)(90mm) = 81.233mm
--> SIN(25.5)(90mm) = 38.746mm

(b)
--> 107deg - 71.5deg = 35.5deg
--> COS (35.5)x(110) = 89.553
--> SIN (35.5)x(110) = 63.877

(c)
--> 97deg - 71.5deg = 25.5deg
--> COS(25.5)(110mm) = 99.284mm
--> SIN(25.5)(110mm) = 47.356mm

I can tell by that picture you take your bar wrapping seriously :)

Very few threadless stems are offered in the old 73 degree angle, which makes the stem exactly horizontal with a common 73 degree head tube angle.

The next step up is an 80 degree which raises the bars a bit less than 1cm, depending on the exact length. Flipping this stem to raises the bars another 3.5cm, which is a lot.

The next step is an 84 degree, which will raise the bars another 1cm. Flip this stem and will only raise the bars another 2cm.

I'm completely scoobied by stem rise. I searched back through the archives and only got more confused.
So here's my dumb question: my current stem is a little below horizontal. Flipped, it's way over. I'd like to be at or a little above horizontal. There's a nice stem on ebay, a -10 rise. Where will that stem put me?
This spreadsheet was posted by Clary on MTBR a while back. You enter your head tube angle and the stack height, spacers, angle and length for two stems, and it tells you the reach & height difference and shows you a picture. Great for playing around with combinations before you lay out the money.

<a href="http://users.rcn.com/mjness/stem_and_handlebar_comparator.xls">stem_and_handlebar_comparator.xls</a>