Originally Posted by
Moisture
i learned that you should have roughly a 90 degree bend in your elbows when riding your bike. As such, wouldn't this be a general guideline for choosing an ideal stem length? Example. I have never seen, myself included, anyone have a comfortable 90 degree bend at the elbow whilst using a 100mm stem. Unless you already have achieved this right angle in your elbow, wouldn't you want to use whatever length stem it takes to achieve this?
None of this makes any sense at all. Elbow bend, as long as there's some, is quite uninteresting. And that said, while you are completely wrong about all this, the one fact which stands out is that you haven't looked at cyclists to see what elbow bends are used. Try this:
There you have elbow bends of 90°, also greater than and less than. What's immediately obvious in any case, is that stem length has nothing to do with elbow bend, which has every thing to do with hip angle. Yeah, the more you bend over at the hips, the more you have to bend your elbows in order to keep your hands on the bars. Who knew?
Actually, I think you made an error in your OP and didn't mean to talk about elbow bend at all. I'll give you that, OK?