Originally Posted by Kontact

It should be said that the numbers used to describe bars and stems are pretty variable, and you can really get into trouble with a $400 barstem purchase if you miss how they measured them.

Factors are:
1. Sloped drops vs straight, which gives narrower hoods than drops.
2. Which is a real issue if you go by the drop number but only ride the hoods on your current bar.
3. CTC vs OTO. Outside measured bars are 1-1.5cm narrower than center measure. Companies vary this somewhat unpredicatably.
4. Reach. Stem length is already a little inconsistent between makers, but barstems measure the stem length to a somewhat arbitrary point on the tops. And then bar reach it self is considerably variable. So even if your barstem seems to match your current stem length, how long is the reach on the bar section compared to your current bar? Maybe you actually need a different stem length to end up with the right hood reach. (Assuming the same hood, those vary, too.)
5. Hood angle. Since you can't change bar angle, the only way to have a different hood angle is to rotate the hoods higher on the bar. While many barstems keep an even curve to allow for this, raising or lowering the hoods will dramatically change both lever reach from the drops and reach.


So I would not buy a barstem sight-unseen unless you can return it after mounting.