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Avid BB5: restoring stopping power

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Avid BB5: restoring stopping power

Old 09-23-17, 04:30 PM
  #1  
alias5000
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Avid BB5: restoring stopping power

Hi everyone,
I recently got a run-down 2007 Trek 6000 from the bike coop at which I work for a very good price. All main components are in good shape, but I am fairly certain that that bike hasn't seen service in its 10 years and was just donated when worn too far. It has become my project bike and will hopefully replace my slowly disintegrating commuter when it's done.

I am having trouble with servicing the Avid BB5 front disc brake that this bike came with (the rear could be better, but I can skid the wheel). The brake force is not sufficient to get to the point of having the rear wheel lifting off at any effort - not talking about an effort that is comfortable.This is what I have done so far:
  • Clean all brake parts
  • Clean rotors with alcohol (just to be sure)
  • Replace brake pads with new resin ones (Nukeproofs)
  • Break in the brake pads (about 20 hard stops, brake power improved a bit)
  • Replace cables and housing
When I pull the lever as hard as I can, it is not touching the handlebar. To my understanding that rules out all possible cable/housing related issues. The rotors have the shape shown in this listing.

The rotors are sufficiently true to get a brake setup going with very little rubbing and good pad-rotor spacing. I will true them the next time that bike is at the bike coop.


I know that BB5's are not the best disc brakes, but there are enough people that report sufficient performance. That's where I'd like to get to. Upgrading to another disc brake (BB7, hydraulics...) would be my last resort, it would be nicer to make the BB5s work as I've just bought new pads.


Thanks for any comments!
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Old 09-23-17, 04:50 PM
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dsaul
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Try scuffing the braking surface of the rotor with some sandpaper.
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Old 09-23-17, 06:50 PM
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BB5 inner, fixed pad adjustment is just like the BB7 that big knob with a Torx screw in the middle . torx screwdriver makes that easy.

the outer pad adjuster is that little barrel adjuster..

but you can adjust the moving pad by swinging the actuating arm and clamping it on the wire where its close to the disc the desired amount..

BB7 has an outer pad wear adjustment knob (the pads are a bit bigger too)



NB: at my Local shop the recommendation is the opposite of what you did .. a good number of gentile stops to bed the pads to the disc.

so maybe that created your situation.. too aggressive a set of break in stops..



..

Last edited by fietsbob; 09-23-17 at 06:56 PM.
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Old 09-23-17, 07:53 PM
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Originally Posted by fietsbob View Post
BB5 inner, fixed pad adjustment is just like the BB7 that big knob with a Torx screw in the middle . torx screwdriver makes that easy.

the outer pad adjuster is that little barrel adjuster..

but you can adjust the moving pad by swinging the actuating arm and clamping it on the wire where its close to the disc the desired amount..

BB7 has an outer pad wear adjustment knob (the pads are a bit bigger too)
I believe I am fine with the adjustment part. Space between pads and the rotor is a fraction of a mm on both sides. And since I cannot make the brake lever touch the handlebar, the brake adjustment and cable/housing setup should not be part of the problem, right?

Originally Posted by fietsbob View Post
NB: at my Local shop the recommendation is the opposite of what you did .. a good number of gentile stops to bed the pads to the disc.

so maybe that created your situation.. too aggressive a set of break in stops..
Hmm, I felt that after about 10-15 of these stops, breaking power started to increase a bit. It was really sluggish before. Is it always super weak when you start bedding them in?
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Old 09-23-17, 10:26 PM
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i
I cannot guess ... you got a lot of unknowns
and my use is probably completely different : My Disc bike is

BB7, the aftermarket pads Kool Stop Organic

the discs , avid, are on 20" wheels , on my bike friday
I use for transportation through out the wet winter..

Im not a fast rider, I have to use the front brake carefully
or the bike will stop but my body will remain in motion.



there is now low compression housing for cable disc brakes FWIW.. it sells to somebody...






.....

Last edited by fietsbob; 09-23-17 at 10:31 PM.
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Old 09-23-17, 10:39 PM
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get a bigger rotor (and adapter)
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Old 09-24-17, 05:02 PM
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Originally Posted by dsaul View Post
Try scuffing the braking surface of the rotor with some sandpaper.
Thanks, I just did that and cleaned the rotors with alcohol afterwards.
That improved braking power I can now lift off the rear wheel when squeezing very hard (i.e. use 3 fingers on my 2 finger levers). Power and Modulation is still worse than with V-Brakes, but it's getting there.
@xenologer: Yep, have been thinking of that. I will keep an eye out for 180mm rotors at my bike coop on Tuesday. I read that forks have to be designed for rotors of larger size. The Rockshox Dart 1 seems to be designed for 160mm only, but it is hard to find any information on this one on the internet by now.
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Old 09-24-17, 05:09 PM
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Which housing did you use? Compresionless really makes a noticeable difference for both BB5 and BB7. Also make sure your cuts on housing are clean (made with dremel or good shop cutters for compresionless) and filed so they are flat and even
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Old 09-25-17, 08:34 AM
  #9  
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I use this method to adjust my BB5 brakes


I also run compression less housing, it made a big difference.
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Old 09-25-17, 07:19 PM
  #10  
alias5000
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Originally Posted by mongol777 View Post
Which housing did you use? Compresionless really makes a noticeable difference for both BB5 and BB7. Also make sure your cuts on housing are clean (made with dremel or good shop cutters for compresionless) and filed so they are flat and even
I am using standard quality compressible brake housing. Will talk to my LBS to get one cut-to-size compressionless housing (hopefully). Full sets seem to be pretty pricey online. I saw a used Avid Juicy 5 (front) with lever and cables for 30-35 CAD incl. shipping online.

Originally Posted by leob1 View Post
I use this method to adjust my BB5 brakes


I also run compression less housing, it made a big difference.
Thanks for that link, that indeed is a very nice approach.
I think our tandem (using Avid BB7 and 203mm? rotors) uses compressionless brake housing and teflon coated cables. These are the best brakes we own.
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Old 11-26-17, 01:03 AM
  #11  
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Just as an update, my BB5s are now running quite nicely. More details are in my first post about my new winter bike:
Raised a new winter commuter bike [long-ish post]
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