Stem & bar compatibility?

[jpw]

are 25.4 mm and 26 mm incompatible?

[Cicli]

are 25.4 mm and 26 mm incompatible?

Providing you are putting a 25.4 bar in a 26.0 stem and use the proper shim, yes.
Prying open a 25.4 stem and putting in a 26.0 bar will end badly. So, no.

So to answer your question, yes and no.

[oldpotatoe]

are 25.4 mm and 26 mm incompatible?

Not without shims(25.4 handlebar and 26mm stem clamp). On drop handlebars, shims sometimes work, no bar slip, and sometimes they don't. Nitto makes shims specifically for this. The other way around...26mm handlebar and 25.4 stem, may overstress the clamp area or bend the bolt..really hurts to break a stem faceplate or break a bolt.

Not recommended.

[rilz]

I have done it plenty of times, though i probably wouldn't do it on particularly nice stems and bars. Part of me believes that cheap manufacturers might have standard deviations about the same as the difference in diameter.

[ultraman6970]

You can use a reamer to fix a 25.4 onto 26 tho. What will happen? no clue. But back in my country we fix 26 to 26.4 that way because the stems are beefier than 25.4 ones.