Originally Posted by
rpenmanparker
They affect the angle or "rise" of the stem. They raise or lower the bars with a smaller movement to the front or back by about 1/3 the amount of the change in height. Removing the shins sets the stem angle to it's base value.
Thanks for your help. The stem I have now has a 12 degree rise(not sure what that means) but I want to get it as horizontal as possible to extend my reach a bit when I take off the spacers I have the "shim" on the inside, I have the shim inserted and one side of the circular shim says +4 and on the other side of the same shim it says -4. How do I insert this and whch way to achieve the most horizontal angle?
If I take out the shim completely the stem does not fit on the steerer tube.