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Height difference between 105 and a 90 degree stem(3 posts)

Height difference between 105 and a 90 degree stemt-moore
Jun 28, 2003 6:54 AM
Want to replace my 105 degree stem to a 90 degree one. Assuming everything else remains the same, how much will the change in stems lower my handlebars.....Thanks
Depends on the stem length…TFerguson
Jun 28, 2003 8:23 AM
An 80 mm stem would drop about 2 ½ cm.
A 130 mm would drop about 4 cm.

TF
figures are off a bit...C-40
Jun 28, 2003 12:28 PM
The proper way to calculate the difference in height from a change is stem angle uses the angle of the stem above the horizontal.

For example, a 130 by 90 degree stem will have a 17 degree rise with a 73 degree HTA. The vertical rise is 130 x sin17 = 38.0mm. A 105 stem will have 32 degrees of rise and a vertical rise of 130 x sin32 = 68.9. The difference is 30.9mm or 3.09cm.

A close approximation can be figured merely by taking the sine of the difference in angles and multiplying times the stem length. In this case, 130 x sin15 = 33.6mm.

If a stem is being flipped to create a greater rise, like from 80 to 100 degrees, there is a common error that is overlooked when making this calculation. The centerline of the stem extension does not generally intersect the center of the stem clamp. When the stem is flipped to the higher angle, a little of calculated rise will be lost due to the off-center configuration of most stems.