Originally Posted by
woodcraft
Assuming that shoulders were 400mm wide, moving each hand out 20mm
would increase the reach about .4mm- about the thickness of a business card.
Might have to go custom for that stem.
Again, I have a general idea of what I need because I actually got on the bike, made some adjustments, rode the bike, tweaked some adjustments, rode the bike, etc. I have no idea what the measurement difference is between the old and new set up because, like you, I assumed it wouldn't make much of a difference. I was wrong; it did make a difference. I did some general play with Pythagorean theorem, but in the end it's about getting on the bike and riding. But my measurements are probably no better or worse than your assumption that my shoulders were 400mm wide to begin with. I have no clue, so how would you?
No need whatsoever for a custom stem. Between length, angle and spacers you can get pretty much whatever you need (see my screen shot above from the stem calculator). I have never had a problem dialing in a good fit on my bikes - road, gravel, CX, mountain, owned/borrowed/rented. I've averaged 4000 miles a year since 2013, and was probably in the 2400-2600 mile range starting in 2007 (pre-Strava/RidewithGPS). I've never had issues on single day rides up to 200 miles, or multi-day rides in the 350 mile range. I have no doubt there are certain people and bikes that might require a custom stem (similar example: a friend had a custom bar made for his flat-bar gravel/monsterX bike because he couldn't find what he wanted; but even he will admit that had as much to do with "want" as it did "need"), but the rest of us can do just fine with off-the-shelf products.
The current stem is some generic thing (the bike is a house-brand from Performance Bike, the only visible printing on the stem is the torque spec). Using a tape measure with inches, I think the current stem is 85 mm which I know is an uncommon length. It's shorter than several 90mm stems I have lying around, but the tape measure has it longer than 80mm. But I could be wrong. It's a little tough to get a 100% accurate measurement while the stem is on the bike clamping a bar in place.
Anywhoo, you all can continue to armchair quarterback my measurements, wants, needs, and decisions. That's what we often do here. I do it too. In the mean time, I'm going to go play bikes.