Stems

It can be difficult to determine the true rise and reach of a stem just by looking at its description. This value depends on the difference between the stem angle and the head tube angle. This table shows the effective rise and reach for a few stems.

The distances that I use align with the center of the clamp, not the far extreme. As you can see in the diagram below, the A measurement is the distance from the minimum insertion mark to the point where the quill intersects with a line drawn from the center of the handlebar clamp along the stem’s extension. Similarly, the B measurement is of the extension from the center of the clamp to the intersection with the center of the quill.

Measurement	Min insertion-top center (A) [mm]	Reach (B) [mm]	Stem angle [deg]	Headtube angle [deg]	Effective Rise [mm]	Effective Reach [mm]	Weight [g]
Stock	72	95	73	72	70	72
Kalin	60	100	135	72	146	26	392
Nitto Technomic	160	100	73	72	153	50	364
Nitto Dirt Drop	155	100	125	72	227	12	375
Nitto Faceplater 110	160	110	100	72	203	47
Nitto Faceplater 135	160	135	100	72	215	69
Nitto 90-190 85	125	85	90	72	145	42	414
Nitto 90-190 110	125	110	90	72	145	42	414

Figure 1: This diagram shows the measurements and results of the table above.

Computing Effective Lengths

This equation represents the effective rise:

\begin{equation} Rise_{effective} = Asin(\theta_{headtube})+Bsin(\theta_{stem}-\theta_{headtube}) \end{equation}

This equation represents the effective reach:

\begin{equation} Reach_{effective} = Bcos(\theta_{stem}-\theta_{headtube})-Acos(\theta_{headtube}) \end{equation}