Originally Posted by
nhluhr
shallow:
flipped: 120*cos12.5 = 117.16 not flipped: 120*cos24.5 = 109.20mm (diff is 7.96mm)
steep:
flipped: 120*cos10.5 = 118.00 not flipped: 120*cos22.5 = 110.87mm (diff is 7.13mm)
So you might say for all typical bikes, flipping a 120mm 6 degree stem will give you a 7 to 8 mm reach difference. That's pretty damn significant.
Yup! I got about half a centimeter by flipping my 100mm stem down, which helps. The spacers I need under the stem to raise the bars enough to not hurt my back reduced my reach, and the extra 5mm or so increased it back again. Math is cool!