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  1. #1
    mtbr member
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    Disappointing BB7's

    Actually, I have a set of BB7's that are incredible on one bike. I liked them so much I replaced some HFX-9's on my other bike with them, but these new ones feel mushy.

    Here's the setup...

    Kona Coiler (Nice solid feeling brakes):
    Older XT Shift/Brake combo levers
    Avid 5mm Brake housing (standard stuff, nothing fancy)
    Stainless cable
    '06 or '07 (light grey color) BB7's

    K2 Lithium 4.0 (mushy brakes):
    Avid SD-7 levers (dialed out all the way)
    Jagwire 5mm Brake housing
    Stainless cable
    '08 BB7's

    I figured brake housing was brake housing, but I'm starting to wonder if that isn't the case. Both bikes have full-length housing runs. I can see a lot more flex going on with the Jagwire housing on the K2. Both were prepped the same way; dremel cut & small drill bit used to clean out the end by hand. I haven't done a lot of comparing on the levers, but I could see that being part of the problem too. Any thoughts?

    I noticed Nashbar sells a, "Mechanical Disc Brake Cable and Housing Set" that sounds an awful lot like Jagwire Ripcords and is pretty cheap. Is it worth a shot?
    Last edited by Yardstick; 01-07-2008 at 01:33 PM.

  2. #2
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    I had jagwire on my bb7s when I first changed them and didn't perform too well. I've since used shimano xtr cables and housing and it's been excellent.

  3. #3
    Meh.
    Reputation: XSL_WiLL's Avatar
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    It could have to do with the housing runs. Are they nice and smooth? No sharp turns, kinks, excessively long runs, and all that? Did you use a light lube on the cable (Rock n Roll Cable Magic, Boeshield T9, etc)? Are the pads dialed to the correct distances? The caliper centered/alligned correctly?

  4. #4
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    I have Aztec powerlines that are in my opinion the best, since these brakes lack modulation compared to hydra cable install and quality of the the cable is crucial.As you can see by the reviews on cables none are perfect, powerlines are excellent but difficult to install....really have to make sure the outer clear housing does not kink even slightly or the break open however I have had a pair on my hardtail that has lasted four years.I have xtr cables on my Heckler that are nearly as good and less of a hassle, may your bike just feels mushy because of the rear suspension design? with more powerful brakes maybe it is more obvious.Iam going to put powerlines on both bikes...not on the shifters though.Other option is to run full lenght housing if possible, such a finicky component this cursed cables.

  5. #5
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    The runs are very smooth. The tightest arc is probably from the lever to the first hose hold-down on the frame. It's not tight at all. The rest of the run is pretty straight. Same on the front. They are no longer than necessary. I didn't lube them, but I didn't lube the ones on the other bike either. Pads are set right. Caliper is aligned right. The housing is just the spiral wound stuff. There's no longitudinal wires. That's the case on both bikes though. More and more I'm thinking it's the levers. This is the first set of Avid levers I've had in a while.

  6. #6
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    try the powerlines...return them if you are not impressed, my single digit 7 levers work fine, not much flex at the lever.

  7. #7
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    I had a weeker frot BB7 (08) so I took it off and started alignment again. For some reason it improved but there still was difference. So I took it out and braked around the house for about 15 min. The rear skids early, not much improvement but the front one improved dramatically with very hard braking. This was after a week of hard terain mtb! So try to run them in realy hard!

  8. #8
    ballbuster
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    Could it be....

    ... misadjustment?

    If you have been using the barrel adjusters to adjust the brakes, the actuator arm might be bottoming out on the caliper body, causing your mushy feeling with no braking power.

    It's very important to [SIZE="5"]not [/SIZE]just the pad contact point with the inline barrel adjusters.

    Use the barrel adjusters only to take up slack in the housing, and no more. When adjusting the barrel adjusters, dial them up until the actuator arm on the caliper just barely starts to move... and STOP! Take a spot welder and weld the barrel adjusters in place, and tape them over with vulcanizing tape... forget they are even there. Okay, forget the tack welding and tape, but you get the idea.

    Then....

    ... adjust the pad contact point with the little red knobs on the caliper.

    As the pads wear, be sure to take up the slack with the red knobs.

    I can't tell you how many bikes I see with misadjusted Avid BBs in this way.

  9. #9
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    There might be a slight misalignment. I know not to use the barrel adjusters for adjustment other than that initial preload on the cable/housing. I'll check them out and try readjusting the caliper to see if I can get them any more square with the disc.

  10. #10
    Boise
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    My bb5's work great with their Avid levers....I would look at set up and/or cable?

  11. #11
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    I get the same feeling when using Avid Levers vs. Shimano Levers. Shimano seem to be a lot crisper than the Avids.

  12. #12
    pvd
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    Why not just buy some hydraulic brakes? This is yet another reason why cable brakes are junk.

  13. #13
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    i have the same brake setup on my Salsa Ala Carte and they feel great. have you ridden them enough for them to break in? for the first few rides after my installation, i was honestly quite disappointed. but then they finally broke in and it was a WORLD of difference. took a few rides though. i'd put a little drop of lube on them too though where they feed from the housing to the caliper.
    will there be beer?

  14. #14
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    I didn't know that anyone would go to the trouble of using a dremel to cut housing, and then a drill to clear out the end. That's hilarious.

    Anyway, I am willing to bet it's either the cable housing flexing or the pads are not square with the rotor. Either one of those will make the brakes feel pretty crappy. Easiest way to adjust them is to use the pad adjusters to sandwich the rotor in the center of the caliper and bolt it down there, then back off the adjusters a little. Also something that seems to help with the Avids is to slowly tighten the mounting hardware and alternate from one to the other a few times as you tighten. If you just tighten one all the way down then do the other that seems to allow the CPS cones to pull it out of square easier.

  15. #15
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    I got them feeling pretty good. I loosened up all the mounting hardware and ran through the setup again. They looked right before, but that did seem to help a little. The front is extra tough to set up without getting some slight bending in that big, 8" rotor. I also took them for a good long run with some decent downhills this morning. On the trail they actually feel better than just testing on the street (I was one-finger braking the whole way), but they could still be more solid feeling. I might just watch out for some nice Shimano levers for cheap to see if that makes a difference. I think I'll also try the "compressionless" housing from Nashbar for a whopping $7. I might even do that to both bikes for the heck of it.

    I'm biased against hydraulic brakes. I know they're a lot of people's favorites, but I have my unjustified reason for not being a fan. I used to ride with a guy who had hydraulic brakes. He crashed and broke the master cylinder two different times, sending him home early both times. BB7's are darn good mechanical disks and so far I haven't experienced (myself or anyone I've been with) a cable failure.

    It's just the drill bit that I use by hand. An awl just pushes the melted, re-solidified liner around. The bit cuts it out and leaves the end very nice and open. I found it easier than using a razor blade or x-acto to get that stuff out.

  16. #16
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    Quote Originally Posted by Yardstick
    I loosened up all the mounting hardware and ran through the setup again. They looked right before, but that did seem to help a little. The front is extra tough to set up without getting some slight bending in that big, 8" rotor. I also took them for a good long run with some decent downhills this morning. On the trail they actually feel better than just testing on the street (I was one-finger braking the whole way), but they could still be more solid feeling.
    Don't fret about the rotors bending. It's supposed to.

    Moifying Avid's 1/3 / 2/3 caliper spacing guidance slightly, I try to position the caliper so the rotor had as much room as practical to flex in toward the fixed pad.

    I back off the moving pad only enough clicks to get the bite point I want.

    I back off the inboard (fixed) pad to affect modulation -- closer in for a grabbier feel on the front brake, and a few added clicks away for the rear to give me better progression. The rotors both end up flexing a bit. Without this, you would have a very on/off effect.

    I suspect you're very well aware of this since you've been using them successfully on another bike, but it bears repeating, especially since you've taken proper care with the housing prep.
    speedub.nate
    MTBR Hiatus UFN

  17. #17
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    The slight bending under braking I'm not worried about. I do like to set mine up to be grabbier though.

    The rotors flex pretty easy since they're so thin and the larger the diameter rotors flex easier. When you set them up that flex makes it hard to keep the caliper in the proper position. I think that was my biggest problem with the front, which was actually the worst feeling even though it has the shorter cable run.

  18. #18
    it's....
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    Quote Originally Posted by pvd
    Why not just buy some hydraulic brakes? This is yet another reason why cable brakes are junk.
    hydro would be junk too if not setup correct.

  19. #19
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    It is Jagwire from nashbar, you asked earlier. I have never used Jagwire until now. I do not like how easily the outer sheath wears.

    Another tip if and only if you have the full metalic [gold Avid] is to heat the pads till they smoke, ie burn off the oils in the pad. It made a huge difference in how much friction I experienced. It felt like the brakes were mushy feeling. I used a candle, pad about half an inch above the pad, and heated them till the smoke subsided. I tried brake parts cleaner first and the bike still did not stop in a hurry. Anyway, I can lock the front tire now.

    I am sure people who think like the guy who thinks mechanicals are bad has never boiled fluid on a long descent. Cables do not boil.

    Quote Originally Posted by Yardstick
    try the "compressionless" housing from Nashbar for a whopping $7. I might even do that to both bikes for the heck of it.

  20. #20
    Meh.
    Reputation: XSL_WiLL's Avatar
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    Mechanical disc brakes can still fade. In fact... they're more likely to fade than some systems. There's less "stuff" that can absorb the heat. Plus cable brakes cannot self adjust for pad wear... so the lever travel will sink more and more as you go down.

    I'm not putting down the BB7s (they're great brakes)... just pointing out that your argument doesn't really hold up.

  21. #21
    ballbuster
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    Yeah, you're right...

    Quote Originally Posted by pvd
    Why not just buy some hydraulic brakes? This is yet another reason why cable brakes are junk.
    .... and frickin zillions of Avid users out there that are happy with their brakes are all wrong.

  22. #22
    ballbuster
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    You might also try...

    BMX housing.

    I work with a guy who just got a front Avid BB7 road brake for his CX bike. They felt really soft at the lever, and the lever actually bottomed out at the bar unless he dialed in the pads so far they both dragged.

    Turns out his housing was compressing a lot. The LBS suggested using stiffer BMX brake cable housing. Worked like a charm. BMX housing uses straight steel wires down the length of the housing, like shifter cable. It's less flexible, but makes a firmer lever.

  23. #23
    Meh.
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    Right, many BMX bikes use linear housing. Good stuff, but many sets are not long enough to run all the way to the rear. If you got money, check out segmented housing like the Nokon stuff. I think Aztec makes a similar product.

    I would suggest lubing the cables though. It can make a pretty big difference.

  24. #24
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    The Jagwire Ripcords (Nashbar Mechanical disk brake cable set) should have the longitudinal wires like a shifter cable. I went for it since I was in need of a new floor pump too and figured $7 tacked on wasn't too bad for a test. It's 1400mm (~55-inches) long so one length should just reach my rear brake.

  25. #25
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    Saying brakes fade describes every set of brakes. I am 100% sure boiling brake fluid causes braking problems, and very hot brake cables still do their job.

    Fact? Sorry your but your fact is sounding like conjecture. Is there some kind of science backing up the stuff you are talking about that absorbs heat well compared one caliper vs another?

    You are 100% right, the BB7 not self adjusting. If I were in a multi-hour race race that fact would be something I would worry about. Maybe doing the Megalavance in France would make me worry about it too. Othewise it is a non-issue.

    I always use the sintered metal pads, and other than having to burn off the oil I got on the padss onetime I have not had problems. I suppose I could be really really lucky, but I doubt it.

    Quote Originally Posted by XSL_WiLL
    Mechanical disc brakes can still fade. In fact... they're more likely to fade than some systems. There's less "stuff" that can absorb the heat. Plus cable brakes cannot self adjust for pad wear... so the lever travel will sink more and more as you go down.


    I'm not putting down the BB7s (they're great brakes)... just pointing out that your argument doesn't really hold up.

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