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  1. #1
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    My BB7's feel like cheese graters

    I've got some older BB7 calipers with a Shimano rotor on the front and an Avid G2CS rotor on the rear (both 160mm). I get a very rough feel when stopping hard, like the rotors are grating the pads on both ends, more so on the front. The rotors have very minimal run-out, probably <1mm.

  2. #2
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    Have you check the pads? I'd make sure there weren't any burrs or chunks taken out of them. Not typical, but it can happen. You can file them down with fine grit sandpaper to smooth them out if there are any burrs sticking out.
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  3. #3
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    I just installed new pads on the rear about 200 miles ago (some Avid aluminum backed pads), which might explain why the rear is less harsh. Maybe I'll try removing the pads and sandpapering the friction surface, and put a bit of a chamfer on the leading edges of the pads.

  4. #4
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    are you sure that the pads are properly located over the rotors, and not on the rotor arms? Aren't Shimano rotors a bit narrower than the usual BB7 rotors?

  5. #5
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    Quote Originally Posted by dumper View Post
    are you sure that the pads are properly located over the rotors, and not on the rotor arms? Aren't Shimano rotors a bit narrower than the usual BB7 rotors?
    The Shimano rotor is .2mm thinner (measured with a micrometer). The pads don't look to be sitting any lower on the rotor than they should, if that's what you mean.

  6. #6
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    Quote Originally Posted by DirtyR View Post
    The Shimano rotor is .2mm thinner (measured with a micrometer). The pads don't look to be sitting any lower on the rotor than they should, if that's what you mean.
    I think dumper was referring to the distance shown in the attached picture. Assuming this is not the problem and you feel you've set/aligned everything properly, I would recommend sanding and cleaning both rotors and pads. Get everything aligned properly again, go through a proper bed-in procedure and they should work as good as new.

  7. #7
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    Quote Originally Posted by Too_Fast_46 View Post
    I think dumper was referring to the distance shown in the attached picture. Assuming this is not the problem and you feel you've set/aligned everything properly, I would recommend sanding and cleaning both rotors and pads. Get everything aligned properly again, go through a proper bed-in procedure and they should work as good as new.
    For some reason I'm not seeing the image. The calipers looked to be lined up properly. I'll sandpaper everything up and take it for a ride and see how that does.

  8. #8
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    Quote Originally Posted by DirtyR View Post
    For some reason I'm not seeing the image. The calipers looked to be lined up properly. I'll sandpaper everything up and take it for a ride and see how that does.
    ya, not seeing an image either, but I know what he's saying and guessing he's probably right as it happened to me, though diff rotors.. the rear edge of the pad (actually the leading edge I guess as it's the back of the pad but it's the first part of the pad in contact with the rotor as in rotates into the caliper) anyway.. it was just clipping the area where the arm of the rotor comes up to the actual braking face. Didn't figure it out right away till the wear marks started showing on the rotor.. was nasty at first, then it chipped out a chunk of the corner of the pad at which time it just became an annoying pulse like effect... sounds like just what is happening to you. You can just add a few more washers or something under the mounting cup/washer thingies (brain fart for the name Sram has for them ) I opted to get a proper rotor for the calipers as I find adding washers kinda weakens an area like that that is under some pretty high stress!
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  9. #9
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    Quote Originally Posted by thomllama View Post
    ya, not seeing an image either, but I know what he's saying and guessing he's probably right as it happened to me, though diff rotors.. the rear edge of the pad (actually the leading edge I guess as it's the back of the pad but it's the first part of the pad in contact with the rotor as in rotates into the caliper) anyway.. it was just clipping the area where the arm of the rotor comes up to the actual braking face. Didn't figure it out right away till the wear marks started showing on the rotor.. was nasty at first, then it chipped out a chunk of the corner of the pad at which time it just became an annoying pulse like effect... sounds like just what is happening to you. You can just add a few more washers or something under the mounting cup/washer thingies (brain fart for the name Sram has for them ) I opted to get a proper rotor for the calipers as I find adding washers kinda weakens an area like that that is under some pretty high stress!
    Now I understand, this makes perfect sense. The pad surface area on the Shimano rotor is more narrow than the Avid, and the pads are contacting some of the area just below where it should. I guess I need to order a new Avid rotor. I'm pretty certain this is the problem. Thanks for the help!!!

  10. #10
    Huckin' trails
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    Quote Originally Posted by DirtyR View Post
    Now I understand, this makes perfect sense. The pad surface area on the Shimano rotor is more narrow than the Avid, and the pads are contacting some of the area just below where it should. I guess I need to order a new Avid rotor. I'm pretty certain this is the problem. Thanks for the help!!!
    If it helps, I find Hayes V's rotors (old generation, see pics attached) to work very well with mech calipers and BB7's. I have two V8 and a 203 G2CS and the V really makes for a nice braking and seems to stay true longer. It is the exact same caliper and pads on both bikes. Note how much braking surface the V8 offers compared to the G2...
    Attached Thumbnails Attached Thumbnails My BB7's feel like cheese graters-imageuploadedbytapatalk1330147382.679618.jpg  

    My BB7's feel like cheese graters-imageuploadedbytapatalk1330147416.697718.jpg  

    My BB7's feel like cheese graters-imageuploadedbytapatalk1330147459.314558.jpg  

    My BB7's feel like cheese graters-imageuploadedbytapatalk1330147608.213921.jpg  

    My BB7's feel like cheese graters-imageuploadedbytapatalk1330147750.593716.jpg  

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  11. #11
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    Damn, I just got rid of some Hayes rotors just like that. I found another G2CS rotor in my garage, I just need to get a centerlock to 6 bolt adapter to mount it up. In the meantime I'll keep my eyes open for a couple of Hayes rotors.

  12. #12
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    like I have posted several times on mtbr, the best thing about having Hayes hydros on your bike, is when you get tired of screwing around with them, the Hayes rotors work great with BB7s!

  13. #13
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    Oops

    Quote Originally Posted by DirtyR View Post
    For some reason I'm not seeing the image. The calipers looked to be lined up properly. I'll sandpaper everything up and take it for a ride and see how that does.
    I apologize, that would be because I forgot to attach it, but I think you get the point now.

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