Is all hydro brake line for dot the same dimension?

[eddief]

Or better yet is there special tubing for dot and for mineral oil?

The reason I'm asking is I had my shop install a set of Zeno quick couplers on my new Force hydros that included the SRAM brake lines. The couplers are leaking a bit under applied brake pressure.

When I had a set of Zenos on the previous version of the bike with Shimano hydros I never had an issue.

Wondering if each brand of brake line has an identical outside diameter cuz it's my suspicion the answer may be no and the SRAM line might be smaller than the line on my Ultegra bike. And when the fitting are locked into place they are not snug enough.

[Dave]

The OD should always be 5mm. There are 3 layers - the inside tube, then some support fabric, then the outer layer. The inside has to be different for DOT fluid. Any seals elsewhere are usually EPDM rubber for DOT fluid. If coupling seals are made for mineral oil, they won't work with DOT fluid.