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Old 02-13-12, 08:59 PM   #1
AndreyT
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SRAM BB7 and the barrel nut on the caliper end of the cable

I have Specialized TriCross bike with disc brakes. The stock setup uses SRAM BB5 brakes with barrel nut located at the very end of the brake cable (no barrel nuts at the levers, no inline barrel nuts). The nut actually works against the "cable guide" arm of the brake, as shown in this picture



I'm planning to switch from BB5 to BB7. However, the similar "cable guide" arm (whatever the proper name for that arm is) on BB7 has some sort of long plastic (or rubber) sleeve sticking out of it. I presume the end of the cable goes into that sleeve



So, what would be the proper way to install BB7 on my bike if I want to keep my current brake cables? Can I just remove and throw away the black sleeve and end up with the setup similar to what I currently have on BB5? Or is it more complicated with BB7?
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Old 02-13-12, 09:12 PM   #2
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BB7 package comes with inline cable adjusters.

and no, you can not replace those rubber sleeves with an inline barrel adjuster, because there are no threads for such a device to screw onto.
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Old 02-13-12, 09:36 PM   #3
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Thanks for the reply. I just noticed that the barrel adjusters that I have now is actually part of the BB5 brake, not an independent part. I.e. there's no meaningful way to reuse them with BB7 (in addition to the fact that BB7 is not threaded there). So, I'll have to install inline adjusters then....

Last edited by AndreyT; 02-14-12 at 09:21 AM.
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Old 02-13-12, 10:17 PM   #4
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Why are you switching?

I ask because I've got a Tricross with the BB5 brakes and they are driving me crazy.
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Old 02-14-12, 12:58 AM   #5
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The outer red knob on the BB7 can be turned to compensate for pad wear, and so there is no need for an in-line adjuster. The BB5 does not have this adjustment knob, and this is one of the main differences between the two models. By using the adjustment knob, you do not change the angle of the arm that the cable is clamped to when doing the adjustment, which Avid say is important for optimum performance.

Both the BB5 and BB7 work very well for me. If your rotor is straight, the caliper is aligned well, and the pad position is good then they perform very well - so well in fact that I can't imagine why anyone would want to deal with the hassle of hydraulic systems.
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Old 02-14-12, 01:09 AM   #6
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I ask because I've got a Tricross with the BB5 brakes and they are driving me crazy.
You know, I'm actually perfectly happy with my BB5's, even though I read that some people don't like them. They only reason I'm switching is that I'd like to have more easily adjustable pads. Also, I just intuitively like bigger pads of BB7 more. Otherwise, there's no reason for me to switch, since by current BB5's work well. I'll probably just put my BB5's on another bike, while my TriCross will get BB7.
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Old 02-14-12, 01:13 AM   #7
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The inline adjuster's purpose is to properly adjust the Road BB-7's cable tension (slack) when used with drop-bar brake handles.
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Old 02-14-12, 01:18 AM   #8
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Actually Jagwire rocket II adjusters fit perfectly in BB7s if you don't want to use the inline adjusters.
http://jagwireusa.com/index.php/prod...cket_Adjusters
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Old 02-14-12, 01:19 AM   #9
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If you remove the rubber sleeve, you can fit a hollow bolt and nut into that space. There are no threads, but when you have it set up, you can unscrew the nut a bit to increase tension. Ask at a shop that deals in used bike parts. These bolts are the kind that go in headset brake stops on old centerpull brakes.
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Old 02-14-12, 09:22 AM   #10
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Actually Jagwire rocket II adjusters fit perfectly in BB7s if you don't want to use the inline adjusters.
http://jagwireusa.com/index.php/prod...cket_Adjusters
When you say "fit perfectly in BB7s" do you mean that they can be installed on the brake end of the cable (as opposed to the lever end)? If so, then how does it work? Do they somehow fit inside that sleeve on BB7?
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Old 02-14-12, 04:18 PM   #11
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On the caliper end. You'd have to take off the rubber sleeve, but you could add a piece of heat shrink or some self sealing silicone tape if you're worried about it.

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Originally Posted by AndreyT View Post
When you say "fit perfectly in BB7s" do you mean that they can be installed on the brake end of the cable (as opposed to the lever end)? If so, then how does it work? Do they somehow fit inside that sleeve on BB7?
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Old 02-14-12, 04:32 PM   #12
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I'm with chris-w on this, bb5 used the barrel adjuster for the moving pad adjustment.
7 adds a knob for that, other adjustments are on the brake lever , if an MTB type..
have speedial levers and the dial changes the way the lever works, some ,
I can dial back the front a bit, with 20"wheels even a 160 disc is relatively huge.

inline adjuster is just that , place it in the housing some where that is convenient.

the other ones just sit on the end of the housing against the stop,
right at the brake..

Last edited by fietsbob; 02-14-12 at 05:11 PM.
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Old 02-14-12, 04:47 PM   #13
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The outer red knob on the BB7 can be turned to compensate for pad wear, and so there is no need for an in-line adjuster.
+1. The barrel adjusters on the brake levers attached to my BB7's stay screwed all the way in and will not be moved as long as there are BB7's attached to the other end of the cable. The adjustment at the calipers are all that's needed.
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Old 02-14-12, 07:44 PM   #14
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For road use, which I assume are the type of levers you are using with the TriCross, I don't use a cable adjuster on the rear with BB7. I can get the feel and lever distance for lock-up threshold in the ball park by pre-loading the cable at the pinch bolt. However, the front requires an in-line adjuster for optimum modulation, this is where I need it most. Use the outside knob to lightly touch the rotor with the pad, then back off one indent, then extend the BB7 kit supplied in-line adjuster to barely brush the rotor with the pad, and back off whatever degree of turn it takes for the rotor to rotate without rubbing. You will discover quickly there is nothing redundant about the in-line adjuster; it goes where the broader tolerance of the outside knob can't.
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Old 02-16-12, 01:59 AM   #15
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I just got my new BB7's and installed the front one. The SRAM's installation instructions say that the torque arm on the brake should remain in its fully relaxed position when connecting the cable. I tried to follow this requirement and ended up with a considerable dead zone at the beginning of the brake lever travel. The brakes felt very mushy, and I couldn't get any decent braking regardless of how hard I was squeezing the lever. Moreover, on further inspection I discovered that at the very beginning of the braking action, when the cable just begins to pull at the torque arm, the brake pads actually move slightly apart (!), and only later, as I continue to pull the cable, begin to close on the brake disc. When I release the brake lever, I get the reverse behavior: the pads spread apart, as they should, but at the very last moment they again move towards each other a little bit. (Technically, only one pad is moving, of course, but let me put it that way anyway.)

This results, for example, in the following weird effect: if the brakes are adjusted to rub the disc very very lightly, then a very slight pull of the brake lever stops the rubbing, i.e. pulling the lever makes the pads to spread. As long as one avoids advancing the torque arm (per SRAM's instructions) it is very difficult (if not impossible) to adjust this brake to avoid rubbing and at the same time get a decent braking action.

Basically, BB7 seems to have some excessive "slack" built into its mechanics. In order to make these brakes work properly (and to avoid the aforementioned "opposite" brake pad action), one has to "dial out" that slack. I.e., just as Werkin said above, the brake cable has to be pretensioned, which can be done by slightly advancing the torque arm from its fully relaxed position before connecting the cable. The cable adjusters should work well for that purpose as well, also allowing for easy fine tuning.

Last edited by AndreyT; 02-17-12 at 01:40 AM.
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Old 02-16-12, 12:24 PM   #16
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First I agree the arm should be tensioned, not slacked, and I'm aware of the behavior you're stating. However, it seems a bit extreme in your case. I'm sure you're competent and most of the things I'm about to mention have been considered, but I'm covering most of the bases anyway. I suggest removing the pads and spring, look for a burr on any of the stamped features on the back of the pad, a speck on the piston, and for a casting flaw on the caliper leading & trailing edges. Sounds like the pad is rocking for whatever reason. Reinstall the pads and spring paying close attention to spring retention, and be sure the pad is pressed in completely. Slide the pad locking clip on the caliper fore & aft to see if there is a change. Ride the bike and bed the pads at moderate speed. If the pad is still cocked, realign the caliper, this time start with the outboard knob turned 10 clicks in, followed by tightening the inboard (fixed) side knob. If there is a build issue with the fork or stay ISO mount, there may not be enough side play available for the caliper to align correctly with the standard 1/3 - 2/3 gap recommended by the instructions.

Last edited by Werkin; 02-16-12 at 12:31 PM.
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