I need to replace the fork on a friend’s 2022 Cervelo Soloist with integrated brake hoses.
It’s a SRAM build, so has their Thingamajig fittings on the end of the hose where they go into the shifters. I will need to pull the front brake hose back through the bars and stem in order to drop the fork. Since the fitting is too large to pull through the holes in the bar, it’s typical to cut the fittings off and put new fittings on when you reinstall but I’m worried the cables will be too short to reinstall.
Can I “unscrew” the existing Thingamajig so I can pull the hose through the bars, then reinstall a new Thingamajig back into the end of the hose when I put on the new fork? If I have to cut the hose to provide a “clean end”, is there a minimum amount I need to cut?
I haven’t heard this discussed before, but since the Thingamajigs basically screw in, it makes sense that they can be unscrewed without cutting the hose. It seems like as long as I put in a new Thingamajig it should seal okay. Or am I missing something?
I don’t know about SRAM fittings. Certainly with the Shimano ones you have to cut them off the hose, and if the hose is too short after that, you have to fit new hose.
Reusing hydraulic fittings is not recommended. It can be done, I’ve done it myself when I was in emergency but you are introducing a non zero probability of brake failure into the system. Brakes are supposed to be 100 % reliable.
The olive is not reusable, it is meant to be crushed and capture the hose in the process. You could maybe get the insert pin out but they’re not expensive to buy, they might even come as a kit with the olive. Keep in mind that the thread on the insert-pin is reversed, from memory you’ll need a T10 spanner
The Stealthamajig uses a threaded barb, I have sometimes been able to unthread the barb with the olive attached but when I’ve done this I’ve still trimmed the clamped part of the hose off and used a fresh barb and olive to put the line back together. If you unthread them like this you can mitigate by a few mm how much hose you’re cutting so if there’s a little wiggle room I’d say that’s your best bet.
Thanks for the responses. As Aidan pointed out, SRAM uses a barb that threads in, while Shimano’s is pressed in. This is why there’s no option except cutting the end of the hose for Shimano. And I’m not planning on reusing anything but the end of the hose. @Aidan_Phipps I’ll probably take your advice and trim off at least a few mm off the end to get a fresh edge to screw in the new barb.
Bike mechanic here. The barb supports the inside of the hose so it doesn’t collapse and pinch closed when compressed by the olive. SRAM chooses to thread their barb so it can be installed by threading it in with a Torx T8 instead of pressing it in with a more expensive barb driver tool like Shimano and others. When the barb, olive, and hose are installed, the compression fitting threads into the lever or caliper and crimps down on the outside of the relatively soft olive and mushes the inside diameter against the hose and the outside diameter against the inside of the lever or caliper body. Basically, it squeezes the olive and displaces the aluminum (permanent deformation) in all directions to seal any gaps. It’s not intended to be removed and reused. If the olive has already been smushed down to a smaller size and you remove and reinstall it, it’s no longer large enough to seal any gaps. This is a common sealing method in lots of other industries. Automotive, heavy equipment, etc. A soft metal like copper, brass or aluminum is used as a single use gasket, and it must be replaced with a new one during disassembly/assembly. You have to cut off the old olive and barb, which shortens the hose by about 16mm (5/8”). Usually, the rear brake has an extra inch or two of hose inside the downtube because the builder purposely shoved some extra in there. Front brake hoses, unfortunately are a pretty straight shot from the caliper to the lever. The only way to get extra hose in there is to shove extra in the handlebar and it needs to be an aero bar with some room inside it. Unfortunately, fully internal cable routing often results in having to replace the hose(s) when replacing a frame, fork, headset, stem, handlebar, lever, or caliper. SRAM makes five different hose assemblies. The hose itself is all the same. The fittings are the difference. Silver banjo, black banjo, angled banjo, double compression fittings and I forget the last one. We stock a pair of each (10 hoses total, just for SRAM). This is why a lot of mechanics are against fully internal routing on low and mid level bikes. It adds cost, time and complexity. Sure, go full internal on S-Works level bikes. That customer paid $15k for the bike, he can afford the extra cost to service it, but it’s not great for the guy who buys a $3k bike and is surprised at the cost for parts and labor to rip half his bike apart to replace a common wear item like a headset bearing.
Thanks for your detailed response Greg. I don’t intend to reuse any hardware, and understand that there is no way to remove a Shimano barb without cutting the end of the hose. But since the Thingamajigs “unscrew”, can I screw in a NEW barb and olive into the uncut end of the hose? Or does the Thingamajig need “virgin hose” to screw into?
I’ve never tried to unscrew a SRAM barb. The olive is tightly crimped onto the hose. It should be, it’s part of the seal. You can’t back the barb out without bringing the olive with it because the olive threads onto the barb (reverse/left hand thread) and the barb has a shoulder that won’t pass through the olive’s threads. You have a barb inside the hose, an olive outside the hose, the female part of the lever, the hose itself and the compression fitting which is concave on the end that makes contact with the olive. When you thread the compression fitting into the lever, it compresses all of the parts together and mushes the soft olive into every nook and cranny to create a seal. The olive deforms outwards to seal against the lever and the compression fitting and it also mushes down against the hose and traps the hose between the olive and barb. The torque spec is 6Nm and I actually use a torque wrench every time. When you remove the hose from the lever, you’ll see that the the olive is deformed and crimped down onto the hose.
The hose is a few layers, kinda’ like a coax cable. SRAM specifies that DOT grease (orange colored) must be used on the barb when threading it into the hose or you risk cutting the inner liner of the hose. According to them, this is the reason that all the old Avid Elixer’s pulled in moisture and stopped working. I always thread the barb into a fresh cut end to avoid the potential of a cut/torn liner from the old barb. This is only in instances where a barb was installed in the hose and capped with a bullet. Santa Cruz bikes ship that way.
Like anything, the manufacturer provides specific instructions but a lot of shortcuts still actually work and folks have to decide what level of risk they’re okay with. I have a reputation for being a good mechanic and I prefer to follow the manufacturers’ guidelines. Some engineer decided that it needs to be a certain way and I’m just the downstream mechanic following instructions. If something goes wrong, I need to be able to say “It wasn’t me”.
Thanks again for the thoughtful response Greg. I didn’t realize that the olive would not be able to be unscrewed from the barb. To be honest, I’ve only ever installed them, but thought it was worth a shot to prevent possibly having to replace the brake hoses. I’ll probably try anyway, but at least now have a better idea what the odds are.