Results 1 to 9 of 9
  1. #1
    mtbr member
    Reputation:
    Join Date
    May 2009
    Posts
    50

    BB7s on a monocog 29er

    Hey folks, just recently got a 29er, and decided to put disc brakes on it. This is the first time installing them so it's a little confusing to me. Had a few questions / comments.

    First of all, I had a hell of a time putting the front rotor on. The rotor kept wobbling and scraping against the inboard pad, even with both pads adjusted fully open. I spent an hour or so trying to figure out what was going on, aligning it and re-aligning it. Thought I had installed wrong, or that the outer edges of the rotor were touching the caliper body, or my rotor was warped. Finally I realized the mounting screw was so long that the end of the screw was protuding all the way onto the rotor. So every time a rotor spoke went by, the screw was pushing against the spoke, flexing the rotor into the inboard pad. Finally put the screw on the bench grinder for a second and took care of that.
    Was a little curious if that's a common issue or I'm just one "lucky" guy.

    Anyways, I got that front on and decided to just try that out before I put the rear on. I rode around for a bit trying to break it in, doing a bunch of hard stops, but it still seems really weak. Not sure how much it takes to break these things in. The rear v-brake seems way more responsive than the disc. I've never had disc brakes before, so I'm not really sure what to expect.
    I got 160mm for both front and rear. I'm starting to wonder now if that is maybe a little small for me on a 29er. (I weigh about 185lbs)

    I've also read a few people's comments on here saying that the bb7 roundagons are kind crappy, and that g3 rotors are a good upgrade. Does the rotor really make a huge difference?

    Well, now I'm trying to install the rear brake and I've got a question about the mounting of the caliper. The mounting tab on the frame has slots for mounting screws to go in, so you can rock the caliper back and forth. I was wondering how I'm supposed to know what the proper position for this is? The front mount did not have these sort of slots, so it was a more straightforward install in that regard.

  2. #2
    mtbr member
    Reputation: cackalacky's Avatar
    Join Date
    Sep 2008
    Posts
    515
    Hi,
    This video helped me out a lot:

    http://www.youtube.com/watch?v=x1kezXQVnLY

    Took a couple of rides to break mine in, but now I love them. Work almost as good as my old deore hydraulics. I do think the roundagons are not the greatest. But I plan on wearing them out before replacing. Anyway, hope this helps, good luck!

  3. #3
    PCC
    PCC is offline
    mtbr member
    Reputation:
    Join Date
    Sep 2005
    Posts
    1,046
    Quote Originally Posted by peepsalot
    I got 160mm for both front and rear. I'm starting to wonder now if that is maybe a little small for me on a 29er. (I weigh about 185lbs)

    I've also read a few people's comments on here saying that the bb7 roundagons are kind crappy, and that g3 rotors are a good upgrade. Does the rotor really make a huge difference?

    Well, now I'm trying to install the rear brake and I've got a question about the mounting of the caliper. The mounting tab on the frame has slots for mounting screws to go in, so you can rock the caliper back and forth. I was wondering how I'm supposed to know what the proper position for this is? The front mount did not have these sort of slots, so it was a more straightforward install in that regard.
    For your weight you probably should be running 185mm front rotors and, maybe, even a 185mm rear. A larger rotor will give you more braking performance for the dollar than anything else you can do to your bike. In order to get better braking while keeping the 160mm rotors would require you to get top-end brake systems.

    Roundagons have a bad reputation because they're noisy, and don't allow for efficient evacuation of off-gassing of the brake pads as well as getting rid of water/mud that has gotten onto the rotors. They also don't cool as well, leading to overheating of the braking system which affects performance.

    When dealing with slots, just push the adapter all the way down until it seats then tighten down the bolts.

    What levers are you using?

  4. #4
    mtbr member
    Reputation: Vespasianus's Avatar
    Join Date
    Apr 2008
    Posts
    3,268
    Quote Originally Posted by peepsalot
    Hey folks, just recently got a 29er, and decided to put disc brakes on it. This is the first time installing them so it's a little confusing to me. Had a few questions / comments.

    First of all, I had a hell of a time putting the front rotor on. The rotor kept wobbling and scraping against the inboard pad, even with both pads adjusted fully open. I spent an hour or so trying to figure out what was going on, aligning it and re-aligning it. Thought I had installed wrong, or that the outer edges of the rotor were touching the caliper body, or my rotor was warped. Finally I realized the mounting screw was so long that the end of the screw was protuding all the way onto the rotor. So every time a rotor spoke went by, the screw was pushing against the spoke, flexing the rotor into the inboard pad. Finally put the screw on the bench grinder for a second and took care of that.
    Was a little curious if that's a common issue or I'm just one "lucky" guy.

    Anyways, I got that front on and decided to just try that out before I put the rear on. I rode around for a bit trying to break it in, doing a bunch of hard stops, but it still seems really weak. Not sure how much it takes to break these things in. The rear v-brake seems way more responsive than the disc. I've never had disc brakes before, so I'm not really sure what to expect.
    I got 160mm for both front and rear. I'm starting to wonder now if that is maybe a little small for me on a 29er. (I weigh about 185lbs)

    I've also read a few people's comments on here saying that the bb7 roundagons are kind crappy, and that g3 rotors are a good upgrade. Does the rotor really make a huge difference?

    Well, now I'm trying to install the rear brake and I've got a question about the mounting of the caliper. The mounting tab on the frame has slots for mounting screws to go in, so you can rock the caliper back and forth. I was wondering how I'm supposed to know what the proper position for this is? The front mount did not have these sort of slots, so it was a more straightforward install in that regard.
    I am close to 200lbs and find the 160 to be fine. I am sure 185 would be better but 160 will work fine.

    BB7 are really easy to set-up. Loosen the cable, loosen the CPS bolts, turn the inboard and outboard pads so they bind the rotor, tighten the CPS bolts, tighten the cable and turn the inboard out outboard pads out so that the inboard (stationary one) is close and the outboard (moving one) is just a little further out. That should work.

    The pads and rotors will take a few good rides to bed in. After that, you should have one finger braking. Cables can improve feel. I just recently switched to Gore cables and the difference is pretty amazing.

    I would also say that Avid rotors are light but are prone to warp. You can bend them easily (but carefully!) back into shape or get other heavier but stronger rotors.

  5. #5
    Nouveau Retrogrouch SuperModerator
    Reputation: shiggy's Avatar
    Join Date
    Dec 1998
    Posts
    48,000
    Quote Originally Posted by peepsalot
    ... Finally I realized the mounting screw was so long that the end of the screw was protuding all the way onto the rotor. So every time a rotor spoke went by, the screw was pushing against the spoke, flexing the rotor into the inboard pad. Finally put the screw on the bench grinder for a second and took care of that.
    Was a little curious if that's a common issue or I'm just one "lucky" guy...
    Common issue with steel fork and frames. The disc tabs are usually thinner than those on aluminum forks and frames.

    I use a couple of washers under each bolt head.
    mtbtires.com
    The trouble with common sense is it is no longer common

  6. #6
    mtbr member
    Reputation:
    Join Date
    May 2009
    Posts
    50
    Quote Originally Posted by PCC
    What levers are you using?
    Just the stock ones that came with the bike. They say Tektro on them.

  7. #7
    PCC
    PCC is offline
    mtbr member
    Reputation:
    Join Date
    Sep 2005
    Posts
    1,046
    Upgrade your levers to Avid Speed Dial levers before you do anything else. I wrote off BB7s on my Cannondale because they didn't meet my expectations for braking power. I sold them then with the rebranded Tektro levers that my bike came with then bought some new BB7s a few years later for my son's mountain bike. I used Speed Dial levers and, OMG, they work almost as well as my Hope Mono-Minis that I paid a small fortune for! I upgraded his front rotor to a 185 because I had the adapter laying around and the rotor was given to me, practically brand new with only about 50 miles on it. I had to tell my son to take it easy on that front brake for fear that he would endo when using it.

  8. #8
    mtbr member
    Reputation:
    Join Date
    Jul 2009
    Posts
    125
    I have a Monocog 29er and thinking of putting the BB7 up front. Rotor size has me confused. How do you move the caliper in or out to compensate for the different rotor size. It looks like it comes with 160,185 or 205 if I remember right. Thanks, MikeB

  9. #9
    Always Learning
    Reputation: BruceBrown's Avatar
    Join Date
    Jan 2004
    Posts
    8,934
    Quote Originally Posted by WMBigs
    I have a Monocog 29er and thinking of putting the BB7 up front. Rotor size has me confused. How do you move the caliper in or out to compensate for the different rotor size. It looks like it comes with 160,185 or 205 if I remember right. Thanks, MikeB
    The adapter comes in various flavors for each of the size. You can run 160, 165, 180, 185 or 203 up front. The rear can go down to 140 using the front 160mm adapter.

    In terms of rotor size, power and what each individual rider needs - it depends. I used to run 185mm front and rear. Moved down to 180mm Alligator Windcutters front and rear. And this season moved down to 160f/140r with the Alligator Windcutters on all of my bikes. At 180 lbs, I've found the 160/140 combo to be just fine and dandy. I've had them in the mountains, races, mud, wet and been very impressed. I use Ripcords and high end levers (Ultimates and Pauls).

    BB

    DosNinerConAspens

    NoTubes Volume

    Sugar2009

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •