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When sanding the stem for a bend, I thought about what happens to the stem material above and below the centerline of the bend radius. I realized that the material on the outer surface will be stretched / elongated and the material in the inside of the bend will be compressed. (just look at the inside radius of an exhaust pipe at a bend)

Okay, on this stem, the top of the stem is pretty much a straight line from the button to about half way up the shank.

The bottom of the stem has had MORE material removed. At the shank/stem joint, the profile of the stem pretty much follows the curve of the shank, then curves gently (concave) toward the button.

Is it a waste of time (am I over-thinking this) to prep a stem so when the bend is made, the compressed material on the bottom half is about equal to the stretched material on the top?

You can click the pic below for a larger image...

Kim,

I think you're "overthinking" it, but I think those are actually good thoughts. The difference between this and exhaust tubing--which I've bent my fair share of--is that exhaust tubing is thin walled and hollow, so the metal actually shrinks/stretches when bent. In this situation, the flexibility of the rubber just allows it to compress I think. Nonetheless, when you bend that stem, you're gonna have a very pretty pipe. Nice job.

TJ

Mmmm Navy Flake.

i´ve actully been thinking the same thing,
when i bent thick parts of the stem, it seemed that the effect you are
discriving happens, well got out of the "problem" by properly heating the stem.

i was thinking that if you don´t heat the stem over all, the "cold" part near the
bent portion, might create an tension, which could affect the bent stem to
straighten for example in hot sun light more easily. ive heard some pipes doing this.