Stem angles

[jpw]

If a stem is descibed as being minus 4 degrees what does that actually mean?

[Dave]

That angle is relative to the centerline of the steering tube. In road bike terms it would be an 86 degree stem (90-4 = 86). To get the angle with the ground, subtract the head tube angle (like 73) from 86 degrees and you get an upward angle of 13 degrees. The old standard quill stems were mostly 73 degrees, so the stem was approximately horizontal.

[Tobias]

Also, if it only says “minus” 4 degrees, it may suggest that the stem is not made to be reversed, or flipped up side down. Most modern stems with that angle would be listed as +/- 4 degrees.

Most earlier threadless stems had the logo printed only in one direction, and in rare cases the face plate may be designed to work (i.e. -- be stronger) in one direction only. Most new ones can be flipped to be plus or minus, but it's worth confirming if you plan to go plus 4 at any time.

[soulspinner]

That angle is relative to the centerline of the steering tube. In road bike terms it would be an 86 degree stem (90-4 = 86). To get the angle with the ground, subtract the head tube angle (like 73) from 86 degrees and you get an upward angle of 13 degrees. The old standard quill stems were mostly 73 degrees, so the stem was approximately horizontal.


Daves explanation is shown on the Habanaro website for those of us who need the visual...