Probably a daft question, but I’ve never thought about it before. I’ve just shortened the brake hose on my front brake.

I understand that the olive is crushed as you tighten the bolt to create a seal and hold the hose in place but how does this actually work and what stops the hose just pulling through the centre of the bolt as you tighten it?

Looking at the olive on the piece of cut hose it almost looks as if the olive is pushing against the flange of the insert which would pull the hose into the lever as it was tightens but an uncrushed olive will pass freely over the barb (I’d actually forgotten to fit the olive before tapping in the barb and just slipped it on afterwards).

As I said, it’s probably a daft question, but I’m interested.

Just all held in by tightness I reckon.

The olive deforms slightly and compresses onto the outside of the hose when the collar nut is tightened onto it, the barb inside the hose stops that compression from collapsing the hose, and the compression holds the whole thing together inside the collar nut.

The olive deforms under the pressure of tightening the nut.

As it deforms it mounds to the brake body and inner nut shape by expanding in diameter , very slightly.

It also crimps down on the outer hose diameter creating the necessary seal.

That’s why the olive can only be used once.

The olive is crushed against the hose when you tighten the nut, thats why the edges of the olive are tapered, to match the inside of the lever and locking nut. True the hose could be pulled out if the force was high enough, but it would more likely tear the hose or at least strip off the outer layer (but both of those are very difficult to achieve!)

The bolt is tapered on the inside so clamps the olive and therefore the hose in place. Doesn’t take a huge amount of force to rip out a hose though, if your bars spin in a crash there’s always a chance it’ll happen

That’s why the olive can only be used once.

I’ve reused one before, but it was only to fit a new lever, so the hose wasn’t shortened and the olive left in place on the hose. I figured it was going back exactly as it was before so should be ok.

I’m not for one minute saying you’re wrong, because I know they’re not really supposed to be reused, more hoping that mine’s ok 😀

That’s why the olive can only be used once.

I’ve reused one before, but it was only to fit a new lever, so the hose wasn’t shortened and the olive left in place on the hose. I figured it was going back exactly as it was before so should be ok.

I’m not for one minute saying you’re wrong, because I know they’re not really supposed to be reused, more hoping that mine’s ok [/quote]

That’s not really ‘reusing’ it, because you’ve not taken it off the hose and then refitted it. So yeah, it’ll be fine.

Yep, if you only undo the hose and don’t cut the hose, then you can reuse the hose with the already crimped olive on it.

Usually though, the hose is shortened and the olive has already deformed to the hose.

Cheers.

So does the tightening process actually pull the hose into the lever as it’s tighten or could it pull through as the nut is tightened?

Its the gubbins. The gubbins get tightened against the doodah and that makes a perfect seal.

So does the tightening process actually pull the hose into the lever as it’s tighten or could it pull through as the nut is tightened?

As you said earlier the hose is loose in the olive until tightened, so yes the hose can pull out until you have tightened it up. It needs to be held in place as you tighten, no massive force required as long as its in the lever enough to for the olive to be past the end of the hose, not half hanging out.

As others have said, you can undo and pull the hose and crimped olive out to check its gone on correctly, then reassemble with no issue.

Yeah, what STATO said. The hose isn’t actually pulled in when you do things up, so I usually put a little bit of pressure on the hose at first, pushing in towards the lever, just to keep it all nicely snugged up whilst tightening.

Cheers. As I said, I wasn’t arguing on semantics, just checking I won’t die.

Cheers All.

I hadn’t realised that you could remove a hose an refit it to the same lever without using a new olive and barb; that’s handy to know.