To bleed or not to bleed.

ara1973
ara1973 Posts: 15
in Workshop
Hello.

I’ve just purchased a new carbon aero bar with internal routing.

My bike has shimano R785 hydraulic brake levers. Will I get away with detaching the hoses from the brake levers and re attaching without bleeding or installing new olive and barbs?

I guess I’ll find out when I try but wanted some forward advice.

Thanks.

Comments

  • MattFalle
    MattFalle Posts: 11,644
    You’ll have to remove everythingfrom the shifters to feed the lines through the bar, yah? Then obviously bleed as everything will have been disconnected.


    You could just put the lines under the bars but then what’s the point of internal cabling?
    .
    The camera down the willy isn't anything like as bad as it sounds.
  • pippi_langsamer-2
    pippi_langsamer-2 Posts: 1,470
    Yeah, I think what you're planning on doing it will be hard to avoid a bleed.

    I'm about to shorten my hoses on a new Synapse for which I'm hoping to avoid a bleed, but that's shortening the hoses from the caliper ends and not the hoods. Bleed kit on stand-by anyway...
  • david37
    david37 Posts: 1,313
    good luck! its either an easy process or a massive pain in the arse depending on how much room there is.

    You should replace the olive/barb. You will almost certainly have to bleed but unless it needed one anyway a mini bleed should suffice to ensure all air comes out. That is if you managed to get the hose through the bars without getting fluid everywhere (almost impossible).

    The easiest and cleanest option would be to drain, and then full bleed. I say this after some experience. it will make the whole job quicker and less messy.
  • ara1973
    ara1973 Posts: 15
    Thanks. I read this from another site.

    1: The trick is to take off the wheels
    2: then pump the levers until the pads touch
    3: unplug the hoses at the levers
    4: check if your olives are good and can be reused, if not, use new olives, this mean that to be safer you should have a pair of olives beforehand and a pair of insert barbs to be even safer.
    5: switch hoses, and reattach the hoses
    6: use a tire lever or a flat screwdriver to wide the space between the pads and push the oil up again to the reservoir and eliminate possible air bubbles.

    This procedure don't have a 100% success rate so be careful or you will have to bleed your brakes. But I did this to shorten hoses before and it worked fine.

    good luck

    Worth a crack?
  • slowmart
    slowmart Posts: 4,480
    edited January 2021
    @OP. Take the opportunity to get the set up spot on as regards routing and length of cable.

    You want the cables to visually compliment the bike rather than detract.

    I’m doing the same project and I only considered draining the system with a full bleed (same brakes as the OP) and ebayed s works aerofly 1 and the holes for internal routing are er rather small which means it’s going to be a pain so making it as mess free as possible without mineral oil getting everywhere seems a sensible approach. The result will be worth it and beats having my trousers pulled down with the elevated prices for a new bike.

    I liked the result Manon @GCN had when she resprayed her bike using a chameleon spray can. Prep and patience is key and the latter is a commodity I don’t posses that much of .
    “Give a man a fish and feed him for a day. Teach a man to fish and feed him for a lifetime. Teach a man to cycle and he will realize fishing is stupid and boring”

    Desmond Tutu
  • ibr17xvii
    ibr17xvii Posts: 1,065
    ara1973 said:

    Thanks. I read this from another site.

    1: The trick is to take off the wheels
    2: then pump the levers until the pads touch
    3: unplug the hoses at the levers
    4: check if your olives are good and can be reused, if not, use new olives, this mean that to be safer you should have a pair of olives beforehand and a pair of insert barbs to be even safer.
    5: switch hoses, and reattach the hoses
    6: use a tire lever or a flat screwdriver to wide the space between the pads and push the oil up again to the reservoir and eliminate possible air bubbles.

    This procedure don't have a 100% success rate so be careful or you will have to bleed your brakes. But I did this to shorten hoses before and it worked fine.

    good luck

    Worth a crack?


    I've no experience with brake bleeds at all but #2 sounds like a massive risk of popping the pistons out?
  • ed1973
    ed1973 Posts: 284
    Just coming into the road bike world from an mtb background, I’ve done more brake bleeds than I dare to mention and can honestly state, don’t pull the levers with no disc attached, huge possibility of popping out a piston especially if one side is just a little sticky.
  • mini_basser
    mini_basser Posts: 12
    I'm in the exact same position with my build. Was really hoping I could avoid having to bleed mine, but this thread is hammering home the realisation that I'm going to have to 😭
  • david37
    david37 Posts: 1,313
    mini_basser said:

    I'm in the exact same position with my build. Was really hoping I could avoid having to bleed mine, but this thread is hammering home the realisation that I'm going to have to 😭

    Bleeding brakes is a skill everyone can learn and once done the fear is gone. over time it is even a mostly mess free activity. And it will save you a ton of money and time.

    First time might be a mess though :D

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