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  1. #1
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    Avid juicy ultimate / bad brake smell??

    i just bought a new mtb with Avid juicy ultimate 185mm brakes.
    went out in the mountains for the first time and whilst riding down very fast on the road i noticed some vibration on the rear tire when braking. about midway down i made a stop and got a very strong smell of burning brakes like that of a semi-truck thats been riding its brakes too hard on steeps.

    so i'm wondering if somthing is wrong with them, if this is normal or if i was just too hard on them, or???

    this is my first time using hydraulic brakes or disc brakes for the matter and
    i'm new to mtb if it isn't obvious.

    thanks in advance for any reply's

  2. #2
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    It's mostly normal as long as you don't have a pad dragging due to a sticking caliper or misaligned caliper body. If you were on the brakes very much then you're going to heat them up and yeah, you get that resin smell from hot pads.

    I hope you broke them in properly first before heading to the extended downhills...if not, it's possible to glaze the rotor and/or pads that way. It can be fixed with some fine sandpaper and breaking them in again, if that happened. Sometimes the pads will be shot and you'll need to replace them. Usually it's fine to scuff and re-bed.

    If your frame and fork will take it, you might consider going to a 203mm rotor if you do a lot of steeps. Or at least on the front. Best solution is to lay off the brakes, or to start-stop several times instead of just applying them the whole time.

  3. #3
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    how do you properly brake in the brakes? and being that i didn't, how can i tell if the pads and rotors are glazed?

  4. #4
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    I don't break in my pads. Just normal stopping will break them in soon enough, but if your riding a fast road or steep downhill it would be wise to break them in and test thoroughly before heading out.

    I like to wipe my rotors down with isopropyl alcohol once every few weeks depending on how many miles I've ridden. I'll also take my pads out if I hear any unusual noises and lightly buff them across a piece of medium sandpaper.

  5. #5
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    Well, I'd say ride the bike as is on the flats and some small hills....if the brakes work ok and if you can get them to bite hard at low speed then you're probably fine. A glazed rotor is often discolored a little from the heat but it's hard to tell. A bedded-in rotor is nice and shiny just like on your car, but so is a glazed one. The pads also get shiny unless you're in mud/grit that scuffs them. Glazed pads are super slick....slightly less slick for normal pads. I know, that doesn't help much. Ride it and if they seem to be working well (Juicy's should work very nicely) then ok.

    If they aren't stopping well, then get some 91% isopropyl alcohol from walmart and wipe down both sides of the rotor surface and each pad. This should remove most contaminants (car exhaust, grime, some oils/lubes). See if that helps. If not, then remove then from the bike and use a stiff brush or 600g sandpaper with a paste of Ajax powder and scrub them well. Reinstall and they should work....keep in mind that after scrubbing they may need to bed-in again to work best.

    (btw, use 91% isopropyl, or denatured alcohol. Don't use rubbing alcohol (has oils in it) or the usual 70% ispropyl (not strong enough to do much). Auto brake cleaners are hit and miss...some leave a residue and some don't. Pure acetone is also ok, but don't use mineral spirits, paint thinner, turpentine, kerosene, gasoline, etc...all leave oily residues.)

    Bedding in a brake is just meshing the pads to the rotor, pretty much like a car except it takes a little longer. What happens is that the pad resins embed into the pores of the rotor metal and create a slick, mated surface. At that point, your brakes will work as well as they're able to provided they aren't contaminated and that everything is set up correctly. To bed them in, you can either ride normally on moderate trails or you can find a hill and go down it, braking one caliper at a time and coming almost to a stop....takes from 5-20 times each caliper depending on the speed and the brakes. Basically you just use them...but using a virgin disc brake on an extended downhill is a good way to muck it up sometimes. It's reversible, though...you didn't ruin anything.

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