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  1. #1
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    Mono Mini Lost Power after Big Ride

    I just put a 180 mm Mono Mini on the front of my Blur. I broke it in as recommended by Hope and it felt great for one 3-4 hour ride. Then I did an all-day epic ride with some long, heavy braking descents (over 8,000 feet of descending total). The next day I was tuning my bike up and noticed that the front brake has lost some power (will not lock up with a 2.24 mutano raptor on pavement or hard pack) and moans/squeals when I brake hard.

    Have the pads glazed over? I don't have any reason to think that I have contaminated the pad. Are the monos leaking like the old minis? If they are, is there a temporary fix for this set of pads I can use before I get the calipers straightened out?

    Thanks in advance for any input you might have.

  2. #2
    UKMac
    Guest

    Is the lever still firm?

    If you have a leak you will most likely be able to pull the lever all the way to the bar (of course air in the system would allow this too, but air in new brakes sounds unlikely). If it does appear you have a leak check the bleed nipple; I have a couple of friends whoís Monos were shipped with lose bleed nipples.

    Also, did you shim the brake carefully? When I installed my Minis I initially didn't face the mounts and didn't get the caliper quite square. As a result my braking performance deteriorated as the pads wore unevenly. If you didn't face your fork mounts and shim carefully, one long ride like you describe may be enough to cause problems.

    There are lots of other possible explanations, so it would be helpful if you could describe and changes in the lever action, feel or anything else that you might have noticed. Good luck.

  3. #3
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    Thanks for the input. Yes, the lever is still firm so it sounds like leakage is not the issue.

    I'll check the shimming and see if the caliper is square to the rotor, although it looked like it was before. I have not faced the fork, hopefully that is not necessary.

    Do the mono pads glaze up on long descents leading to this kind of deteriation of performance?

    Quote Originally Posted by UKMac
    If you have a leak you will most likely be able to pull the lever all the way to the bar (of course air in the system would allow this too, but air in new brakes sounds unlikely). If it does appear you have a leak check the bleed nipple; I have a couple of friends whoís Monos were shipped with lose bleed nipples.

    Also, did you shim the brake carefully? When I installed my Minis I initially didn't face the mounts and didn't get the caliper quite square. As a result my braking performance deteriorated as the pads wore unevenly. If you didn't face your fork mounts and shim carefully, one long ride like you describe may be enough to cause problems.

    There are lots of other possible explanations, so it would be helpful if you could describe and changes in the lever action, feel or anything else that you might have noticed. Good luck.

  4. #4
    UKMac
    Guest

    Have you pulled the pads to inspect them?

    If not, I'd do that next and look to be sure they are wearing evenly. Uneven wear is a sign of alignment problems, which would require re-shimming. Also you can look to see if the pad appears to be glazed. In fact you might just try sanding them down a bit to see if that helps.

    If all that proves negative, I'd try cleaning the rotor with isopropyl alcohol or meths just to be sure. Contamination can happen easily even when youíre careful.

    If you are new to disk brakes this must be a bit frustrating, but stick with it and youíll find it worth the effort. Monos are very good brakes so donít worry, youíll get to the bottom of it soon.

  5. #5
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    Quote Originally Posted by UKMac
    If not, I'd do that next and look to be sure they are wearing evenly. Uneven wear is a sign of alignment problems, which would require re-shimming. Also you can look to see if the pad appears to be glazed. In fact you might just try sanding them down a bit to see if that helps.

    If all that proves negative, I'd try cleaning the rotor with isopropyl alcohol or meths just to be sure. Contamination can happen easily even when youíre careful.

    If you are new to disk brakes this must be a bit frustrating, but stick with it and youíll find it worth the effort. Monos are very good brakes so donít worry, youíll get to the bottom of it soon.
    So I pulled the pads, they looked fine -- I'm not sure what a glazed pad looks like anyway, but they were not worn unevenly. I wiped down the rotors with the rubbing alcohol which didn't change much in the driveway. Anyway, on my ride last night the brake actually worked great.

    Thanks again for the help.

  6. #6
    UKMac
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    Good news!

    Hopefully that's the last of it.

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