Bicycle Mechanics - Avid BB7's crappy though I followed all advanced "instructions"

The parts: 4 brand new sets of BB7 brakes with Avid Speed Dial 7 levers and Jagwire cable/housing. Dremel to cut the front casing (rear did not need cutting). Torque wrench.



I have so far set up 3 sets of bb'7s, multiple times, and I am still not happy with the performance. I would expect to be able to lock up the brakes if I want, right now what I am getting is the brakes won't lock even when I squeeze all the way in. I should not have to pull the lever half way in to begin to stop. Terrible.

I followed this guide http://howtosetuptheavidbb7.weebly.com/how-to-set-up-the-avid-bb7.html to the word. I tried it a few times.

Maybe the pads need wearing in? How bad are they supposed to be before wearing in?

I have read a million threads but it is not really helping. I do see a lot of bend in the rotor when the brake engages. Not sure where to go from here... :crash:

Straighten out the rotor. You can do it dynamically, on the bike, or Park makes a truing tool that fits on their wheel truing stand. They also make a rotor bending tool, although you could just as easily use an adjustable crescent wrench.

Straighten out the rotor. You can do it dynamically, on the bike, or Park makes a truing tool that fits on their wheel truing stand. They also make a rotor bending tool, although you could just as easily use an adjustable crescent wrench.
It doesn't sound like the rotor is warped, just that the rotor is too far from the fixed side of the caliper so it has to flex when the brake is applied. Sounds like an alignment problem.

Make sure the cam that the cable attaches to is rotated all the way to the right before bolting the cable down.

Pads need bedding in before they'll work as they should.
Rotors on mechanical discs have to bend as only one pad moves, the outboard pad pushes the rotor against the inboard pad. Too much bend means something is wrong, either the calliper isn't adjusted properly or the rotor is warped and the pads have to be too far away from the rotor to stop any rubbing.

http://www.twowheelblogs.com/avid-bb7-disc-brake-set-and-tuning (http://www.twowheelblogs.com/avid-bb7-disc-brake-set-and-tuning)

http://www.sram.com/_media/techdocs/2006_BB5and7_English.pdf (http://www.sram.com/_media/techdocs/2006_BB5and7_English.pdf)


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

Did you have the mounting holes for the rotor faced or the paint cleaned off ? Were the rotors cleaned of grease or oil? Most people here have good reviews of BB7's. It will take some time to bed the pads in. Try going down a big hill and do a long stop with the brakes on.

Braking performance sucks until the pads are properly bedded in. A bit of a hill or a grade helps with this process.

It doesn't sound like the rotor is warped, just that the rotor is too far from the fixed side of the caliper so it has to flex when the brake is applied. Sounds like an alignment problem.

BB7s are adjustable on the fixed side (like many cable disk brake calipers) to get the pad close enough to the disk so that this shouldn't be a problem.

Alignment problem--as much as is should work and instructions tell you that it's as simple as just applying the brakes while having the mounting bolts loose, there may still be some hand adjustment needed. Use instructions like this to get close to where you need to be. For fine tuning, sight down the brakes so you can see a sliver of light between the pad and rotor--if that isn't there, loosen the pads at the caliper with the adjustment wheels so that you can see it. Give the wheel a spin. You'll see pretty easy where there's warp in the rotor contacting the pads. Either straighten the rotor at that point, or loosen the mounting bolts about half a turn only, making them loose enough to adjust, but not so that they are flopping around loose. At that point, you can move the caliper slightly where you need it in order to get things aligned. Once things are aligned, tighten the mounting bolts in stages, adjust the fixed side in until it is just rubbing and then back it off one click. Adjust on the other side to however tight you like you brakes.

BB7s are adjustable on the fixed side (like many cable disk brake calipers) to get the pad close enough to the disk so that this shouldn't be a problem.

Alignment problem--as much as is should work and instructions tell you that it's as simple as just applying the brakes while having the mounting bolts loose, there may still be some hand adjustment needed. Use instructions like this to get close to where you need to be. For fine tuning, sight down the brakes so you can see a sliver of light between the pad and rotor--if that isn't there, loosen the pads at the caliper with the adjustment wheels so that you can see it. Give the wheel a spin. You'll see pretty easy where there's warp in the rotor contacting the pads. Either straighten the rotor at that point, or loosen the mounting bolts about half a turn only, making them loose enough to adjust, but not so that they are flopping around loose. At that point, you can move the caliper slightly where you need it in order to get things aligned. Once things are aligned, tighten the mounting bolts in stages, adjust the fixed side in until it is just rubbing and then back it off one click. Adjust on the other side to however tight you like you brakes.

This is what works for me.
I use a T25 mounted on an extension to make the inside pad adjustment that much easier - the wheel can be a bit hard to access and turn with fingers.

I had no problem setting up my Road BB7, but did not achieve 'skidding power' until I went to a 203mm rotor. The 160mm rotor that came with the caliper was a 'wimp' compared to the V-brake/booster I replaced up front. A 185mm rotor was a little better, but still no match. Thw 203mm rotor did the trick! Now I have 'skidding power' on dry pavement front and rear.:thumb: My frame is not set up for disc, so I kept the V-brake/booster on the rear.

Here's the thing, in order to stop the front wheel, I have to pull the lever almost to the handle bar. However, I set up the cable according to instructions... the tiniest movement of the lever causes the brake cable arm to move, which I assume means there is no slack.
It just seems weird to have to pull the lever that far, and it is not comfortable. Could it be a cable issue, maybe there is slack or something despite the fact that it is very responsive?

How far away from the rotor is the outer pad ?
How far away from the rotor is the inner pad ?
Have you tried turning the pad adjuster knobs to get the pads closer to the rotor or are the pads already close to the rotor ?
Is your rotor warped, does it have any sideways movement as it turns ?
Does your calliper and rotor have the same clearances as the image below ?

http://sites.google.com/site/ageechen/_/rsrc/1250499344676/Home/bike/avid-bb7-bb5-manual/2142_200708151127441.gif

Do your levers and the BB7 model match? There is a road BB7 and mountain BB7, each of which requires a different amount of cable pull to work properly. The mountain version is for V-brake type levers, the road version is for other types of lever. Maybe you are using the mountain version of the brake with normal levers?

Do what Cobba says and your brakes will work fine. So many users love these brakes, do you really think you've followed all the instructions?

How far away from the rotor is the outer pad ?
How far away from the rotor is the inner pad ?
Have you tried turning the pad adjuster knobs to get the pads closer to the rotor or are the pads already close to the rotor ?
Is your rotor warped, does it have any sideways movement as it turns ?
Does your calliper and rotor have the same clearances as the image below ?

http://sites.google.com/site/ageechen/_/rsrc/1250499344676/Home/bike/avid-bb7-bb5-manual/2142_200708151127441.gif


Ok, I bought 4 sets of these with matching levers... I followed all instructions, is it possible I flubbed up? Possible but not likely, I bought all the parts brand new from Pricepoint. I tried setting them up 2 ways, one with the rotor centred, the other with the 1/3 2/3 ratio. Same thing. I can move the pads closer but then I get rub.
I am one of those people who follow instructions to the letter, so I don't think I am doing anything obvious wrong, I think there is something else going on here maybe...


Do your levers and the BB7 model match? There is a road BB7 and mountain BB7, each of which requires a different amount of cable pull to work properly. The mountain version is for V-brake type levers, the road version is for other types of lever. Maybe you are using the mountain version of the brake with normal levers?


Hmmmmmmmmmmmmmmmmm not sure on this one, I ordered from Pricepoint assuming they were matching?

I am finding the answer on the Pricepoint site to someone's question kind of suspicious, could I have bought the wrong levers??

Levers

http://www.pricepoint.com/detail.htm?stylepkey=15253&style_id=035%20AVD2L6&detailName=Avid%20Speed%20Dial%207%20Brake%20Levers%202009

Brakes

http://www.pricepoint.com/detail.htm?stylepkey=18749&style_id=115%20AVDB78&detailName=Avid%20BB7%20Mech%20Disc%20Brake%20Grey%20Fnt/Rer%202009


The brakes are for Trail/XC but there's no info on the levers...



Do what Cobba says and your brakes will work fine. So many users love these brakes, do you really think you've followed all the instructions?

Yes, I have, about 10 times now on 3 different installs. if I am wrong I will gladly admit it once I figure out what I did... I followed blog posts and the actual sram instructions, several times. I tried adjusting it by feel myself, nothing I do works aside from having the pads rub a lot.


Well if it comes down to it I will take it to the shop and ask them what I am doing wrong...

Those levers and brakes are compatible.

Sounds like one of two things might be wrong, either you have a warped rotor or it could be a problem coming from the brake mounts on the fork/frame.
Where are you getting the rub, is it a continual rub or does it only happen on some parts of the rotor ?
Turn the bike upside down or mount it on a workstand, spin the wheels and have a close look at the rotor while it turns. Look for any sideways movement in it. If there is sideways movement the rotor is warped and will need truing.

There's quite a few brakes where, in order to get them set up right, the actuation arm down at the caliper actually needs to be in a slightly but not fully actuated position. Loosen the cable pinch screw, pull some cable through, and set the arm about 1/3 into it's range of motion. After that, use either the adjuster at the lever, or at the cable stop on the caliper to fine tune it.

There's quite a few brakes where, in order to get them set up right, the actuation arm down at the caliper actually needs to be in a slightly but not fully actuated position. Loosen the cable pinch screw, pull some cable through, and set the arm about 1/3 into it's range of motion. After that, use either the adjuster at the lever, or at the cable stop on the caliper to fine tune it.

You shouldn't need to do that, the outboard pad on the BB7 can be adjusted inwards with the outboard pad adjuster knob/dial the same way the inboard pad can be adjusted inwards with the inboard pad adjuster knob/dial.
That sort of adjustment is what you'd do on a brake that only has a inboard pad which can be adjusted.

Make sure the cam that the cable attaches to is rotated all the way to the right before bolting the cable down. Do this. Also, I use Jagwire braided cable housing and ends for zero flex, and on a Tandem to boot, lots of cable. works awesome, 203mm rotor.

You shouldn't need to do that....

SRAM specifically says not to do that, they instruct the user to adjust the pads, don't preload the caliper's arm.

Maybe the caliper isn't aligned correctly?

The brakes are for Trail/XC but there's no info on the levers...

The levers are compatible, however they are described as having an adjustable leverage ratio. Have you tried using it at each end of this adjustment range?

As others have said, I had no problem setting up a set of these brakes to work extremely well (great stopping power and modulation for very little hand pressure).

The levers are compatible, however they are described as having an adjustable leverage ratio. Have you tried using it at each end of this adjustment range?

As others have said, I had no problem setting up a set of these brakes to work extremely well (great stopping power and modulation for very little hand pressure).



Adjustable leverage ratio ? I am unsure as to what this means aside from the modulation screw which doesn't seem to do much (speed dial).

Pay the LBS, your safety is at risk.

Pay the LBS, your safety is at risk.

lol, no its not that extreme... they aren't that poor, they seem to be getting better. I am not an unsafe or silly person, like those guys who ride with no brakes on a freewheel and use their foot to stop :) I rode about 20k today in rush hour on the new brakes. They still won't get that "feel" I am expecting from good discs. I am about to go readjust em again to see if the arm orientation is affecting it. I tend to be a perfectionist and I just don't think they are doing what I think they should be.

Have you checked those rotors yet to see if they are true ?


Re. Speed Dials

http://www.sram.com/_media/techdocs/speed-dial-7-install.pdf (http://www.sram.com/_media/techdocs/speed-dial-7-install.pdf)

http://www.booboodog.net/images/avid-speed-dial-2.jpg


Firmer position = More cable pull, Firmer feel, Less mechanical leverage - Harder to put force on the brake

Softer position = Less cable pull, Softer feel, More mechanical leverage - Easier to put force on the brake

Think of the Firmer position as a large chainring and the Softer position as a small chainring, the large chainring can turn the back wheel more but it'll be harder to do, the small chainring will turn the wheel less but it'll be easier to do.

Something kind of interesting, on the 2 bikes I have installed the BB7's to, one bike is adjusted a bit differently and is starting to feel much better, this is the bike I adjusted so that the rotor was in the middle (followed the blog instructions in my original post). The bike with the 1/3 2/3 seems inferior. Of course there could be other variables but now that the brakes are getting broke in, I will reset the front of bike #2 as per those blog instructions and see if it improves.

Have you checked to see if the rotors are warped yet ? Even new rotors can have slight warps.

A warped rotor that deflects 0.5mm can affect how the brake is set up and how well it performs.
0.5mm, 0.75mm, 1mm, etc, are small numbers and mightn't seem much but it's a fair bit when you consider that a brake caliper might only have a gap of 4mm of which a 2mm rotor fits between and the maximum 30mm or so that the Torque Arm (caliper arm) moves will only equate to 2mm maybe 2.5mm of Outboard Pad movement. The clearance between the pad/rotor so there's no rub is another measurement to add to the equation, the bigger the distance the more lever pull.

When pad/rotor clearances are subtracted from the 2mm or so that the outer pad can move it will take a lot more lever pull to get full pad/rotor connection on a warped rotor than a true rotor.
With a 1mm rotor warp and 0.5mm of pad/rotor clearance on each side so there's no pad/rotor rub a brake lever would basically need to be pulled all the way in to get full pad/rotor connection. A true rotor with the same clearances, the lever would only need to be pulled half way to get the same pad/rotor connection.

With the 1/3 - 2/3 rotor/caliper clearance setup the rotor will actually end up in a more central position when the brake is applied as the outer pad pushes the rotor it flexes onto the inner pad. With the centralized rotor/caliper clearance setup the rotor will end up much closer to the inside part of the caliper when the brake is applied.

As there's not much clearance between the caliper and rotor the 1/3 - 2/3 setup could potentially stop the rotor from rubbing against the inside of the caliper if there was excessive pad wear without making adjustments. With a centralized rotor that's being pushed inwards, excessive pad wear without making adjustments could potentially make the rotor rub on the inside of the caliper.




Brake pad break-in period.
It may take anywhere from 20 to 40 complete stops to break in Avid pads.