I am (slowly) getting round to building up the Shimano R785 groupset on to my new road bike but life and missing parts keep getting in the way.

I am new to hydraulics so please humor me with simple questions.

The main one I have at the moment is that I’ve installed the barb, but the diameter isn’t big enough to hold the olive on. I am aware the olive is crushed on to the hose by the nut threading into the shifter, but should the barb at least be wide enough to prevent the olive from slipping off the end?

It’s a Shimano BH59 fitting.

Thanks!

No is the simple answer

No, the olive can slide on the hose, and over the barb.

You need to be careful to make sure the hose is fully seated, and kept pushed into the lever as you tighten the compression nut.