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Brakes spongey after having the bike upside-down ?

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  • 28-12-2023 1:00pm
    #1
    Usjes
    Registered Users Posts: 326 ✭✭


    Hi,

    My bike has hydraulic disc brakes. I have found that when I leave it upside-down for a while to work on it when I put it right side up again and pull the brake levers they don't engage. I can pull them until the lever touches the handle bar, I have to pump them a number of times and each time I pull them they 'engage' a bit earlier until finally they are engaging after being pulled only a bit (and are well away from touching the handle-bar). Is this normal ? I don't think they used to behave like this, ie previously if I pulled the brakes before inverting the bike then inverted it, when I righted it again they would engage at the same point first time I pulled them.

    Thanks,

    Usjes.



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    #2
    CramCycle
    Moderators, Sports Moderators Posts: 24,772 Mod ✭✭✭✭CramCycle


    Either need a bleed or a top up, simple enough to do.



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    #3
    Usjes
    Registered Users Posts: 326 ✭✭Usjes


    https://www.boards.ie/discussion/comment/121543526#Comment_121543526

    Well that's the funny thing, I had read previously that spongey brakes indicated that the fluid needed topping up, they have been like this for months and recently I needed new pedals. So I left it in to the bike shop to have the pedals replaced last week and figured I might as well get the brakes serviced while it was there. So they charged me €55 to service the brakes and the receipt reads 'Rear full bleed, Front top up', they did also note that the rear pads and rotor were quite worn and would need to be replaced soon. After this work it is still the case that when I invert the bike the rear brake only becomes spongy, to me it is like they fixed the front break (via top up according to the receipt) but the back break is still spongy. Is it normal for it still to be spongy due to the wear on the disc/pads or does the fact that it is still spongy suggest that it wasn't done properly and I should bring it back to them ?



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    #4
    cletus
    Registered Users Posts: 7,962 ✭✭✭cletus


    I'd bring it back. The brake pistons should be self adjusting as the pads wear, so that shouldn't cause excess travel.

    You could check at the joints to see if they're leaking/weeping, but I wouldn't actually do anything, as the shop can point to that and say it's an issue caused by the work you did, not them.



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    #5
    gn3dr
    Registered Users Posts: 867 ✭✭✭gn3dr


    Why would you turn your bike upside to service it? Keep it upright. Any air in the system will rise to the top which when upside down is your calipers.



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    #6
    cletus
    Registered Users Posts: 7,962 ✭✭✭cletus


    https://www.boards.ie/discussion/comment/121543950#Comment_121543950

    Shouldn't be any air in the system, though, especially after a bleed



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    #7
    gn3dr
    Registered Users Posts: 867 ✭✭✭gn3dr


    https://www.boards.ie/discussion/comment/121544058#Comment_121544058

    Shouldn't in theory but there must be.



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    #8
    cletus
    Registered Users Posts: 7,962 ✭✭✭cletus


    https://www.boards.ie/discussion/comment/121548662#Comment_121548662

    Yep, but the solution is not 'don't turn your bike upside down', it's get the brakes bled and set up properly



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    #9
    CramCycle
    Moderators, Sports Moderators Posts: 24,772 Mod ✭✭✭✭CramCycle


    Probably don't even need to bleed them if they were serviced recently, just open up the reservoir at the top, pour in a bit flick and bend the pipe a bit, close it back up. Yes the bike shop should do it but if you have the fluid in your house, it would certainly be easier.



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    #10
    Alanbt
    Registered Users Posts: 1,146 ✭✭✭Alanbt


    https://www.boards.ie/discussion/comment/121549012#Comment_121549012

    On a very practical level, if this occurs only after putting the bike upside down then very much part of the solution is not to put the bike upside down



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    #11
    cletus
    Registered Users Posts: 7,962 ✭✭✭cletus


    https://www.boards.ie/discussion/comment/121549852#Comment_121549852

    Only insofar as part of the solution if the engine in your car makes funny noise when you start it, is not to start your engine.

    Hydraulics are sealed systems, and there shouldn't be air in that system because air is compressible, and hydraulic systems rely on oil not being compressible.

    You should be able to turn your bike upside down without the brakes going spongy. If you can't, the system isn't sealed, and needs to be fixed, whether that's a joint that's weeping, air in the lines, or whatever.



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    #12
    pairofpears
    Registered Users Posts: 167 ✭✭pairofpears


    What calipers are they as I have the Shimano RS505 on one bike and they have always been known to be not the best as it was Shimanos first set of road calipers.



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    #13
    Whatwicklow
    Registered Users Posts: 676 ✭✭✭Whatwicklow


    Zip tie / tape the brakes on for a few days, Any air will find its way to the master cylinder and your brakes will be prefecly bled



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