Stem angle/length vs. steerer length
 

My road bike has a more upright handlebar position, with a 25deg stem (110). When I bought the bike used, this was the best solution to fitting since the steerer was already cut. I really can't handle the extreme drop position that a 0 or 6 degree stem would offer on that fork. Anyway, I just bought a new fork, and I'm trying to decide how best to configure the stem & steerer length. I want the handlebars in the same exact location relative to the frame, but I could add spacers and go with a shorter low angle stem to achieve this setup. Is there any mechanical advantage/disadvantage (i.e. perhaps less/more stress?) to go with a shallower angle stem? Obviously, a shallower stem will preserve more steerer length, so that's a bonus. Of course, I would need to replace my current stem. Just wanted to see if I'm missing something ... thanks!

BTW, it's a carbon steerer.

I prefer to keep the spacer stack under the stem less than 1" (25mm), though many go taller. If you do cut the fork, leave some room above the stem to make adjustments. You can always make another cut later on if you're 100% settled in to your riding position.

If you can do it with less stack height, I prefer small angle stems, ie. 6° because they're more versatile. Angled stems (not 90°) can be inverted to give you different HB heights. With high angle the difference is too much and only one is usable, but small angle stems give you 2 heights not that far apart, and combined with changing spacers lets you really dial in the position.

Anyway, here's a link to a calculator that will show you graphic comparisons of 2 stems of varying length angle and spaced height.

Happy hunting

If I use my 25deg stem, I would still have 1.25" of spacers under the stem - that's my current setup. This may seem high, but I need this fit because of back issues. It may not be optimal for aerodynamics, but it's optimal for minimizing pain. So, it sounds like you would recommend sticking with the 25deg stem to avoid too high of stack height.

For 1" carbon steerers, the 1" (25 mm) maximum spacer stack under the stem FB mentioned is pretty much what fork manufacturers recommend. For a 1-1/8" steerer the manufacturer's recommended maximum spacer stack varies from 40 mm (most) to 50 mm (Easton).

The carbon steerer is 1-1/8".

Given your height needs,I don't think you can go with a shallower stem, even if you go to 40mm of spacers below. (use the calculator to check), so yes, keep the high angle stem.

Yeah, 40mm of spacers would only save 1/4" of steerer tube - probably with a 17deg stem or similar. So, it sounds like I'm not saving much, or altering the stresses much, by changing the configuration. Not to mention, it would cost $$ for another stem.

carbon stuff steerer is required to be short, so up angled stem is all you have.

if the steerer were steel you'd have more options..