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Old 09-12-2017, 09:38 AM
Mark McM Mark McM is offline
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Join Date: Jun 2006
Posts: 3,902
Originally Posted by veggieburger View Post
Another "deep thought" while riding my bike.

As I lean down on my Zepp stem, I'm exerting a lot of pressure on the faceplate retaining screws. I assume the stem starts out as a solid piece of aluminum, then the excess gets machined away. Cut the faceplate, drill crew holes, you're more or less done. But way back in the day I had a Cinelli Alter that had a faceplate which came down on an angle - so the bars were cradled, and my weight came down more on the stem, less on the hardware. Doesn't that seem like a more sensible design?
The majority of (threadless) stems are intended to be reversible - the stem can be oriented to either give a positive or a negative angle. If the faceplate was at an angle, you'd need to make separate positive and negative angle models.

In addition, I'm not sure that the angled faceplate is actually that much stronger. Some of the largest handlebar forces can be upward (as when pulling on the bars), and more importantly, forces on the handlebar are often highly offset, resulting in a large bending moment on the bars (for example, when rocking the bike in a sprint, and alternating pulling on opposite sides of the bar). These rocking alternating forces pulling on the par would put the entire load on the bolts, magnified by the lever arm of the handlebar.

One design which addresses your concerns are the Ritchey C260 stems, which wraps the bars for a complete 260 degrees:

This design minimizes the loading on the bolts, and if the bolts (or faceplate) do actually break, it the handlebar will remain attached to the stem (although the handlebar will be free to rotate in the stem clamp).
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