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Contaminated disc brake?

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  • 06-09-2019 8:55am
    #1
    Canis Lupus
    Registered Users Posts: 9,893 ✭✭✭


    Was overseas for 2 weeks and say hadn't cycled in a week before, just took the bike to the shops and the back brake feels... spongy? pulls all the way to the handlebar with no stopping power and there's a reasonable squeal at low speed from it.

    It's a giant contact hybrid brake. Literally no issues when I last used it and it's been so long I can't remember if I oiled it after that trip but otherwise I can't think of how the brake....broke....

    Anyway this being my first disc brake does it sound contaminated? Is it easy to clean the rotor and swap brake pads or is it simpler to just drop into store I bought it from.


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    #2
    magicbastarder
    Moderators, Category Moderators, Arts Moderators, Sports Moderators Posts: 48,575 CMod ✭✭✭✭magicbastarder


    the contamination - or possible lack thereof - would not affect lever travel. there could be an issue with the hydraulic fluid or cable slipping, depending on what system it is.
    squealing can also be caused by misaligned pads, which again could be a possibility as something has changed on it.


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    #3
    Canis Lupus
    Registered Users Posts: 9,893 ✭✭✭Canis Lupus


    Strange that it happened whilst I was away, nothing could have been done to it. Will take a proper looksie and see what I can see. Cheers anyway.


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    #4
    magicbastarder
    Moderators, Category Moderators, Arts Moderators, Sports Moderators Posts: 48,575 CMod ✭✭✭✭magicbastarder


    is it cable actuated or hydraulic?


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    #5
    Canis Lupus
    Registered Users Posts: 9,893 ✭✭✭Canis Lupus


    Both I believe. Giant contact use a hybrid system but a cable is directly connected to the lever.

    It's no real big deal, I'll call the shop and ask them to look at it. Once they tell me what went wrong I'll know what to do next time.


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    #6
    smacl
    Moderators, Society & Culture Moderators Posts: 15,725 Mod ✭✭✭✭smacl


    Have you checked the pads? Squealing sounds and spongy feel sounds like the pad is worn out and needs replacement, happened to me a couple of weeks back.


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    #7
    Canis Lupus
    Registered Users Posts: 9,893 ✭✭✭Canis Lupus


    smacl wrote: »
    Have you checked the pads? Squealing sounds and spongy feel sounds like the pad is worn out and needs replacement, happened to me a couple of weeks back.

    Bike is virtually brand new with very few km on it.


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    #8
    mad turnip
    Registered Users Posts: 710 ✭✭✭mad turnip


    Sounds like air has gotten into the hydraulic brake line, maybe due to the cargo hold on the plane depressuring if you were on a plane. The brakes probably just need to be bled. Bike shop will do that for you. If you had the wheels off and the brakes were pulled the pistons may be in a different position than previously try squeezing both brakes on and off about 10 times and see does this resolve it.


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    #9
    Canis Lupus
    Registered Users Posts: 9,893 ✭✭✭Canis Lupus


    I know you all can't wait to hear the answer but was just air in the line. Fixed it free of charge, squealing was just at low speed and it not being able to apply proper grip to the rotor. All is well now.


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