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  1. #1
    29er for the Soul
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    BB7 front rotor drags

    Hi,

    Just bought a used 29er with BB7 brakes on it. Bike was only ridden three times and only on the street. Everything on it is still new including brakes. I just took it out for it's first offroad run. I rode a lot of technical rocky terrain and I was heavy on the brakes. After the ride, I noticed the dragging, not before. Though, I may just not have noticed it before.

    The front rotor drags a bit. I hear a slight metalic scraping sound as the wheel spins. When the Quick Release skewer on the wheel is open, the scraping isn't there, but as soon as I tighten up the wheel to the fork, I get the scraping sound.

    Is this normal? I can't hear it on the rear wheel.

    This is the first bike I have had with disc brakes.

    Bike is a 2009 Novara Ponderosa with BB7 brakes front and rear.

    Thanks

    Socal Rod

  2. #2
    Vaginatarian
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    not normal, could be bent rotor or not adjusted properly
    is the scraping constant or intermittent?
    to adjust brakes , first loosen both adjuster knobs ( red)all the way
    loosen the top 2 fixing bolts
    tighten inside knob 10 clicks
    tighten outside knob all the way
    tighten fixing bolts
    loosen outside knob 5 or 6 clicks
    loosen inside knob the same
    tighten inside knob 1 or 2 clicks at a time and spin wheel listening for rubbing, when you start to hear rubbing loosen a click or 2
    do the same on the outside knob
    thats it, if the rotors bent it probably wont ever not rub, they can be straightened. there is a tool or you can use a crescent wrench tightened up to rotor thickness

  3. #3
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    BB7s are wonderful brakes--easy to adjust. There is a dial on either side of the caliper to adjust the position of the pads. Sometimes, if I'm just dealing with a very light kaching sound, I will just back out the pad a click or two on whichever side is making contact. (Unscrew to back out).

    Be careful to always make sure the inside pad protrudes past the edge of the caliper. You want your rotor forced against that pad when you brake, not against the caliper. This is not an issue with the outside pad.

  4. #4
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    Go to the Park tool site.follow the bb7 adjusting link.its diff.than previous posters suggest.inside knob is all the way IN for starters. Park Tool Co. » ParkTool Blog » Avid® Mechanical Disc Adjustment
    Last edited by 02_NRS; 03-18-2012 at 07:37 AM. Reason: forgot.

  5. #5
    29er for the Soul
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    Hi Jonathan,

    Thank you for your response. Is there an easy way to see which side is making contact?

    Other posters,

    thanks for responding.

    I doubt the rotor is bent. It's never been offroad nor had any evidence of a fall. Bike was pristine when I bought it. (Well now, it's dirty and dusty ) So, Iam leaning towards the issue of misalignment. Dragging noise is constant all the way around. i doubt the previous owner ever rode it as hard as i did yesterday. So, maybe this is all part of the initial breaking in period.

    I will check out the Park link and search for any Youtube videos to help.

    Thanks

    Socal Rod
    Last edited by teachndad; 03-17-2012 at 10:02 PM.

  6. #6
    Fat-tired Roadie
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    It's shockingly easy to introduce a little bit of a warp in a rotor. So don't doubt it until you give the wheel a spin. Then it will be pretty clear, one way or the other.

    If you sight along the rotor, you should be able to see through the caliper. It might take a little doing to figure out the right angle. It can help to do it with a white background. Piece of paper, car, light-colored sidewalk, whatever. That should make it easy to figure out which side is scraping. Then do as suggested in #3.

    I wouldn't re-do the caliper alignment unless I couldn't tune the brakes to be quiet in their current position.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  7. #7
    rebmem rbtm
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    Installation and Setup Guide: http://www.sram.com/sites/default/files/techdocs/2006_BB5and7_English.pdf

    * When you dial out the outboard pad away from the rotor, the brake lever needs to be squeezed for the pad to go to the new position.

  8. #8
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  9. #9
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    Quote Originally Posted by teachndad View Post
    Hi Jonathan,

    Thank you for your response. Is there an easy way to see which side is making contact?
    I put my bike on a stand and shine a flashlight though the caliper while I spin the wheel slowly. If not that, then Andrew's idea of holding the bike over a light background is a good one.

    Read that install guide that Cobba linked to. It never hurts to read the instructions.

    Don't be intimidated by the adjuster knobs. Take the opportunity to experiment. Turn each knob all the way out and all the way in. Observe the effect on the pad placement. The brake will not break.

    The ideal, purist approach might be to loosen the entire caliper and run through the entire caliper alignment and brake adjustment process. Sometimes though, I'm not above just twisting the knobs to provide a big enough pad gap for the rotor to spin in, and then I go ride.

    FWIW, I just wentt through a similar problem with my hydro brakes. Dropped the rear wheel to clean the bike. Got consistent brake rub when I remounted the wheel. Gremlins? ((That's my thinking). There are no adjuster knobs on an Avid Juicy hydro caliper, so I had to loosen the caliper and realign it. Then I had to carefully true the rotor using an adjustable wrench to dial out the last bit of kaching. Realignment is pretty easy. Truing the rotor takes some time and patience.

  10. #10
    29er for the Soul
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    Excellent advice Everyone!

    Thanks, I am on my way.

    I will take it from here.


    Socal Rod

  11. #11
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    My rear brake seems like the pads touch the rotor while riding, specifically when turning. The caliper has been set correctly and the noise only happens when riding the bike, and worse when turning (like the pads lay into the rotor from gravity). When the bikes upside down theres 100% no rubbing or noise. Any ideas? Shimano m575 and a brand new rotor.


    Sorry to thread jack, kinda the same problem though.

  12. #12
    B.Ike
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    BB7's are awesome, but they are not a set it and forget it component. Get to know your brake. I've had to completely reset them trail side after a crash, and it pays to have that knowledge dialled in.

  13. #13
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    brake rub

    Check your hub bearings or if f/s pivot bushings.sounds like the wheel is wondering.try a wiggle test.

  14. #14
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    also be patient

  15. #15
    Trail Tire TV on blogger
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    Quote Originally Posted by teachndad View Post
    ..............

    The front rotor drags a bit. I hear a slight metalic scraping sound as the wheel spins. When the Quick Release skewer on the wheel is open, the scraping isn't there, but as soon as I tighten up the wheel to the fork, I get the scraping sound.
    when tightening the Q-release the wheel can often times shifts, the fork gets pinched, wheel can lean funny in the fork when applying the pressure on the lever.. try putting some weight on the handle bars when tighten the QR and see if it shifts again. Works best if you can get a buddy the full out sit on the bike and lean against the bars. I can almost Guarantee that's what is happening. It's a good practice to weight the forks when attaching the wheel as it makes sure it seats squarely in the fork's drop out.
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  16. #16
    29er for the Soul
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    Quote Originally Posted by thomllama View Post
    when tightening the Q-release the wheel can often times shifts, the fork gets pinched, wheel can lean funny in the fork when applying the pressure on the lever.. try putting some weight on the handle bars when tighten the QR and see if it shifts again. Works best if you can get a buddy the full out sit on the bike and lean against the bars. I can almost Guarantee that's what is happening. It's a good practice to weight the forks when attaching the wheel as it makes sure it seats squarely in the fork's drop out.
    Very interesting. I am learning so much from this thread.

    I wonder if I can turn the bike over and put my weight on the wheel itself by leaning over it, and then tightening it if I don't have someone around to put weight on the bars. Seems like the same principle but upside down.

    I will have more time next weekend to tinker around with all the suggestions. Having the offroad knowledge of full adjustment is good idea.

    cheers

    Socal Rod

  17. #17
    Trail Tire TV on blogger
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    Quote Originally Posted by teachndad View Post
    Very interesting. I am learning so much from this thread.

    I wonder if I can turn the bike over and put my weight on the wheel itself by leaning over it, and then tightening it if I don't have someone around to put weight on the bars. Seems like the same principle but upside down.

    I will have more time next weekend to tinker around with all the suggestions. Having the offroad knowledge of full adjustment is good idea.

    cheers

    Socal Rod
    ya can, but it's not good as the oils and such in the fork are in the wrong areas and then you are compressing it.. better off just standing in front, grab the knuckle of the stem and pulling straight down and tightening the QR. as long as you get at least some compression of the fork you should be good.

    here.. watch episode 2... it's the first tip....
    iTunes - Podcasts - Trail Tire TV by Thomas Lamourine
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  18. #18
    Dissolved member
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    FWIW, I just got a brand new BB7 w/ a 180mm rotor and, out of the box, the rotor is indeed warped. Two out of three Avid CS 2 rotors I have are slightly bent without any apparent reason, they just come like that. You have to adjust the calipers around the rotors' imperfections.

  19. #19
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    warpage

    or use a dial indicator on a tru stand w/the rotor attached to a wheel & fix the rotor. EZ fix.

  20. #20
    Huckin' trails
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    I'll usually set my wheels at the best position it can be, then with a pencil mark where the axle or QR seat on the frame/fork. Remove the wheel, mount the rotor on the wheel and take care to have it center at best. I also like to put a bit of grease on the hub where the rotor sit to prevent corrosion and ease the install. Torque the bolts in a star pattern to allow the best alignment. Then loosely bolt the adaptor to the frame, then turn it counter-clockwise and fully tighten. Mount the caliper loosely if it's not in the way before you install the wheel. Re-install the wheel and set it according to the marks. Squeeze the lever to get the caliper roughly centered and bolt down altering between each bolt. Then release the lever and spin the wheel. Check if the rotor is true and true it if needed. Then do the final adjustments.

    Next time when you take your wheels off, you simply have to align with the marks and play with skewer tension to get the rotor centered.

    Here's a good tutorial to set up mechs. Very helpful.


    http://www.twowheelblogs.com/avid-bb...set-and-tuning
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    topless. that's what all mtb girls do. we go ride, get topless, have pillow fights in the woods, scissor, then ride home!

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