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I set up a shigura system with BL-M8000 levers, MT5 and MT4 Callipers and Magura hoses and shimano parts on the lever end. But I couldn't get even a decent bleed on them. I tried a couple of techniques like pulling the brake lever while pushing oil through the system, but no matter what I did there always came some new bubbles. After bleeding, the levers were super spongy and the bite point moved a lot.

From what I can tell the system has no leaks and the brake levers used to work fine with the original Shimano callipers. The Magura parts are all new, so they shouldn't malfunction either. What can I do to get a better bleed on them?

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    Did you use Shimano Mineral Oil or Magura's Royal Blood (which is very runny mineral oil) ?
    – Criggie
    Commented Jul 28, 2022 at 10:37
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    @Criggie I used Royal Blood (I heard that it makes more sense, because the callipers are already filled with it) Commented Jul 28, 2022 at 10:58
  • @Criggie which brand would you recommend? Commented Jul 28, 2022 at 12:54
  • I deal with magura and was chatting to the shimano rep a few weeks ago who asked about this setup. I was ignorant. What is the supposed benefit of using the Shimano levers in this system instead of, say, changing the Magura lever blade to a more adjustable type?
    – Noise
    Commented Jul 28, 2022 at 12:55
  • @Noise I did this, because my Shimano shifters are directly mounted to the Shimano brake levers. So I can't just install the regular MT5 lever, because the shifters would have no mount. I could get some shift-mix adapter but I don't like the idea of spending 40€ on two pieces of plastic. Also many people claim that Shigura is more powerful than a pure MT5 setup, which would be a nice benefit. Commented Jul 28, 2022 at 13:03

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My experience with Shimano hydraulic levers is that they can trap alot of air in the reservoir. This usually gives the symptom of long lever travel on the first pull and hardening with shorter travel on subsequent pulls. If you have bled the system by pushing fresh fluid up from the bottom and you are confident the caliper is bled well, put the funnel on top of the shimano lever (which you set level), half full of mineral oil (doesn't really matter what type, your 5 year leakproof warranty doesn't apply) and pump the lever; you'll see bubbles of air come up into the funnel. Do this in intervals until you can't get any more air out. Let me know if that helped.

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  • Sounds similar to what I have done, but I will try if that method works. Commented Jul 28, 2022 at 13:19
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    I haven't said, but the bottom end is closed off and finished when you're trying this.
    – Noise
    Commented Jul 28, 2022 at 13:21
  • So I tried doing this and it removed some air, though not much. But still the bite point moves quite a lot and when pulling the brake levers for a couple seconds the pressure falls off quite significantly. Commented Jul 28, 2022 at 15:15
  • @user11914177 I think if the pressure falls off, you have a leak. Regardless of how much air you have in the system, in a properly sealed system pressure should remain constant when you press and hold the lever.
    – MaplePanda
    Commented Jul 28, 2022 at 18:13
  • @MaplePanda so I checked again and I couldn't find any leaks, especially none that could explain such a quick and dramatic pressure fall off Commented Jul 29, 2022 at 9:57
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Infinite bubbles means that air is getting in during the bleed, either from unsound technique or equipment, a faulty hose connection, or a problem with the caliper or lever such as a faulty seal.

What I would do is bleed it exactly like a Shimano brake, except with the Magura fitting at the caliper end. Make the caliper the lowest point, level the bleed port, attach your funnel, fill it, plug it, fill a syringe and attach it, unplug the funnel, and push fluid through. If you get a bunch of bubbles, plug the funnel, remove the syringe fitting, suck the fluid up with it at the caliper end, and recirculate it back through until there are no bubbles coming up. If that point never comes (there are always bubbles), you have an air leak that has to be addressed. Once there are no bubbles coming up, plug the funnel, remove the syringe from the caliper bleed hose and attach a collection bag or bottle, and let it drain a little to see if any bubbles come through, making sure the funnel never runs dry. Then plug the funnel, close the caliper bleed port, unplug the funnel, and flick the lever around as you rotate the bike 45 degrees forwards and back in the stand several times, until no more bubbles come out. Then plug the funnel again and close the lever bleed port.

There's only one way of getting to a hose configuration on a mismatch system where all the hose fitting considerations are "right" or "as-designed" by at least some definition: use a third-party hose system such as Jagwire that enables you to have the caliper end use its Magura fitting and the lever end use the Shimano. Otherwise you're going to have at least an on-paper mismatch between either the barb/olive and the hose (where minor differences in the hose OD/ID can cause problems), or you're mismatching the barb/olive to the thing it's going into. I'm not saying this is definitely the problem, but it's one of the things it could be.

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    Regarding the bleeding part, did you actually try that out? I think it is almost impossible to properly close up a MT5 calliper while oil is pouring out. Magura recommends to put the calliper over the lever before closing the bleed port. And regarding the hoses, I don't really get why only a third party hose could work. If it is designated to work on both brands, it means that there are no (significant) differences in the original hoses anyway. Also I did use the matching olives on each side of the system Commented Jul 28, 2022 at 20:33
  • I ignore that instruction on the various long ebikes I deal with that have them, where there isn't necessarily a practical way of making the caliper the highest point. The way I do it on those bikes is use a Magura syringe with the plunger removed as a funnel, hold the caliper such that the bleed port is pointed up, and quickly remove the syringe and replace it with the bleed screw. In your case though, plugging the funnel at the other end should vacuumize the system such that oil doesn't flow out while you're doing it. Commented Jul 28, 2022 at 20:50
  • For the hose, if the ID and OD are really the same, then yes it would probably work. But generally speaking there's nothing that says that's going to just work. For example, Shimano's different size barbs for BH59 and BH90 due to their different wall thicknesses (same OD, different ID). Ultimately even if you think that part should be good, infinite air means it's coming in from somewhere, so you have to start eliminating possibilities. Commented Jul 28, 2022 at 20:55
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    And the concept with using Jagwire is that you can get fittings that adapt it properly on both ends, such that if the only OEM type fittings available couldn't both go on the same hose, you could still do with the Jagwire one. Commented Jul 28, 2022 at 20:59
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    Anecdotally (from me) the Magura hose using magura olive and barb will seal in a Shimano compression fitting. I have stacks of leftover Magura hose and hardware and have had to use it a few times for "emergency" hose replacements to Shimano brakes. I was very pleased with the results, it's a permanent repair. But for peace of mind always use the right hose/hardware where possible!
    – Noise
    Commented Jul 29, 2022 at 10:06

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