Between working on my and my girlfriend's bikes, I've come across different style compression ferrules (aka sleeves/olives) used in the hydraulic brake systems and would like to know:

  1. What is the purpose of the grove in the middle?
  2. Would it be safe to use a standard brass hydraulic ferrule (straight or curved body) as long as it's rated for similar or higher pressure? (I would continue to use a barbed insert rather than switch to smooth.)

(example 1; example 2; example 3; example 4 "standard")

To be clear, these ferrules and inserts go over/inside single or dual-layered PVC tubing.


1 Answer 1


I think the feature acts like a lock so it fits into the brake well like a seal. These hoses don't need crimping, according to this video. https://youtu.be/z5qIrpGR3yY?si=uP8OnMla9kn24HwP

As for your question on safety, I'm not sure if will fit in the first place.

  • $\begingroup$ Deleting and then re-posting answers is not good - an edit button is available for a reason. $\endgroup$
    – Solar Mike
    Commented Oct 1, 2023 at 8:35
  • $\begingroup$ Okay, I'll try to avoid in the future. I usually edit after feedback. $\endgroup$ Commented Oct 1, 2023 at 8:38
  • $\begingroup$ Or to make them easier to grasp -- important for hand fitting. $\endgroup$
    – david
    Commented Oct 1, 2023 at 20:35
  • $\begingroup$ I think you're onto something, @SamiSafarini. Because the brakes use mineral oil, it would make sense if the grooves allow the surrounding brass to compress the softer, outer tubing while leaving a narrow area less compressed under the groove so there is additional force preventing the hose from sliding out under extreme circumstances or in case oil contaminated the contact surface during assembly. $\endgroup$
    – MJA
    Commented Oct 2, 2023 at 2:42

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