Bicycle Mechanics - Avid BB7 Disc Brake setup

Hi,

I just got my new Trek Portland commuter! (on b/o for over 3 months) I was able to commute on it yesterday and I need some assistance.

The bike came with Avid disc's, BB7 roads and I am a bit unimpressed with the stopping power or lack there of. I have Hyd disk's on my FS and they stop on a dime. All my road bike's have standard brakes and they have more power than these Avids. I live in the Mtns of Western NC, Asheville and brakes are a must, plus dealing with traffic.

They have 105 levers and the bike was setup by my LBS of which I trust. But the rear level squeezes all the way to the bar before I get any stopping power which is little. I had to move my fingers out of the way to keep from pinching them in braking. Yes, I know that 75% of my stopping power comes from the front, but regardless they should require that much, I mean these are disks!

The LBS said that is the nature of these brakes. Is that true?

Any help would be appriciated!

sounds like the rear needs more cable tension. And the brakes need to break in a bit to gain stopping power, usually a few rides.

It's more than just cable tension. It's the amount of cable pull. Standard Avid mechanical disk calipers are meant to be used with V-brake levers.
Avid makes calipers designed specifically for road levers, which don't pull as much as a MTB V-brake lever.
You can buy a little gizmo called a travel agent, which will go really far in improving stopping power. Additionally, you may need to adjust the rear brakes a bit. Here is the basic rundown.

1)Loosen the two bolts holding the caliper to the frame
2)Crank in the big red knobs on the sides of the caliper until the pads are sqeezing the rotor, holding the caliper in place.
3)moving from one bolt to the next, tighten each of the two bolts holding the caliper to the frame a little at a time until fully tight.
4)Back off the inside red knob *just* enough that the pad clears the rotor.
5)Back off the outside knob just enough to clear the rotor, and play with cable tension to adjust feel.

ATN, thanks for the reply.

I will try re-adjusting first then I may get the travel adapter if need be. The front is fine with pull and stop, its just the rear that is weak.

Avid makes calipers designed specifically for road levers, which don't pull as much as a MTB V-brake lever.

Don't you think Trek would have spec'd them on this bike?

It's an adjustment problem that you are having, I have those disc on my bike and it stops amazingly well. I'm using mines on mtb trails and am bombing down it with no fear of brake failure, so i trust them emplicitly.

Don't you think Trek would have spec'd them on this bike?


These are the road versions, which is why I was a bit frustrated.

I will readjust these tonight when I get home. Hopefully they will work better, and I can tell even without riding. If I can apply pressure without hitting the bar then its got to be better.

I know the brakes must "burnish" in and will provide greater stopping power as they age in.

Thanks for all's help.

Paul

They have 105 levers and the bike was setup by my LBS of which I trust. But the rear level squeezes all the way to the bar before I get any stopping power which is little.

What are you using for cable housing? The less cable housing you have and the less it compresses the better.

What are you using for cable housing? The less cable housing you have and the less it compresses the better.

Exactly what came from Trek. Bike was partially assembled upon delivery. LBS just finished off the build.

Paul

any word?

Back at the LBS. They think that the problem lies inside the housing or connection at the shifters. They agree the brakes lack any stopping power and feel nothing but mushy.

Should have the bike back tomorrow.

Thanks!
Paul

here is how to set them up: easy as pie

ps-full stoppage only occurs when they are broken in and mated to the rotor
it takes a few rides
-----------------------------------------------------------------------------
attach brake cable and take up slack so it just makes the arm move,
then back off so it almost does, but doesn't


loosen the entire brake caliper from the mount so it can wiggle

rotate the red dials so the fixed pad (close to spokes) is 2/3 out

rotate the red dial so the moving pad is 1/3 out and the disc is
in between. 1/3 to 2/3 is the balance where the pads should sit
and disc is inbetween...relatively.

now crank the pads equally so they grab the disc and you can't
move the arm any tighter. -now- tighten the caliper bolts.
tighten 1 bolt first, then the other. don't try to tighten them
both equally. one first, all the way...then the other. it should
self-center to the disc. no need to fuss with it much. I was
concerned with my first set of bb7's but it really does go easy....

now
back off the pads red dials quite a bit. squeeze brake. let go

now rotate the spoke side red disc then rotate wheel
till you hear the pad rubbing the disc when rotating wheel

now back it off 1 click or 2 so it is quiet


do the same for the other red dial...till it touches then back off 1 click'
so it is quiet.

the brakes are now set up properly.

THEY WILL feel like mush the first few rides if they are new, the part that
hits the disc and makes noise is not broken in yet, so they will feel soft
for a short time. this is normal. read on

never adjust the cable again as the
pads wear. only use the red dials to compensate for wear.
only adjust cable to the full arm extension length and not more than
that.

NOW
as the pads break in, braking will stink...occasionally re-adjust those red dials and you will
find the brake lever travel gets better and better as the avids break
in to the disc. they will become quite good brakes. give it some time, like 20 miles

you gotta burn off
the microscopic imperfections without glazing the pads with too much heat.

the re-adjust the dials with the 'till it touches then back 1 click' procedure.
do it as many times as they need. soon they will be rock hard, 1 finger action

break them in gently with little and light braking for 2 or 3 rides.


you'll get them sweetened. every 2 or 3 rides retweak the red dials.


you'll get serious brake performance.

the reason hydraulic brakes don't need such minute adjustment all
the time every 2 rides is just the way hydraulics work. hydraulic systems
pad wear is the same, but hydraulic pressure and travel so exceeds
cable performance that it isn't really noticable. itis noticable with cables.

to get the
same performance with a cable brake, you just have to stay on
top of the red-dial and pad-to-disc factor a lot closer. but do it,
and you will get king stopping power.

edzo,

Thanks for the instructions. Got the bike back and still not great. I plan on commuting all week and hopefully the brakes will burnish and improve. This shop had a Portland that the owner rides, he has owned it for several months and has a fair amout of miles on it, but the brakes are not much better feeling on his than mine.

My LBS said they were going to call Avid and discuss with them.

I wanted this bike due to the disk brakes, not sure why, guess just a cool thing to have in the stable. But, I can honestly say that a good set of D/A brakes blow this away, at least right now.

I will keep you posted and the progress at weeks end

Paul

Hi Ltspdpc;
Picked up my Portland last Saturday. Have not had a chance to put any miles on it though, I hope to finish getting it ready to commute on soon, [I need lights on mine to be at work at 6 am].
I am having the same issue with my rear brake as you, I found the caliper was not spot on from assembly, so I adjusted the caliper position and pad setting, This helped lever feel somewhat, will see how it does next ride. I have not put enough miles on it to have the brakes seated in yet. I am considering going to Aztec or Nokon cables and housings for less stretch and compression if they do not improve enough.
So far I think I will enjoy the Portland, the ride reminds me of my old Trek 520 sport bike I had way back when, [before they made it the touring bike with cantilever brakes]. totally destroyed it in a serious crash with a cow sized black lab.
I am having a problem finding a rear rack for panniers for mine, If you commute with panniers what rack are you using?
I bought the Portland for the disc brakes, although Charlotte does not have the hills you have my commute does have some long hills climb up going to work and descend coming home and at 6'2" and 235 I need brakes, I was commuting on a ols Trek 850 converted to road running gear with V-brakes, While the brakes stop ok I found I am eating up pads at a very high rate - even the sever duty shimano xtr's, and the pads become embedded with grit and then going up my rims badly, even more so when it rains. I hoped to eliminate these problems with the Portland,
Well I hope you get your problem solved, let us know how it goes, If you are in charlotte get in touch with me and possibly we could get together for a spin. Ride safe, lr.

Hi LR,
I wish I could say the brakes have improved but not really. I had about 75 miles this past week commuting and I cant say they are much better. Being 6-1 and 175 lbs it shouldnt take that much force to stop me, but the rear lever depresses all the way to the bar. The fronts are fine and very strong, and I am dealing with the lack of rear and just making sure I use both brakes. I am a bit disappointed with that, but everything else is good. The bike handles well, geared well and stable. My LBS is suppose to be contacting Avid about the brake issue but I havent made it in to see if they have.

I am using the Trek rack on mine. It has a quick release bag that mates up with it and is working well. I dont know about panniers but I know you can get some "grocery" bag style bags that mount similar to panniers. I would imagine they have other accesories to mate up but have yet to look into any.

Good Luck in Charlotte! Asheville traffic I am sure is much better and less

Paul

I find your problems a bit puzzling. I certainly believe that both of you are experiencing less than stellar performance from you BB-7s, but we have had (road version) BB-7s on our tandem for nearly a year (~2000 miles). So far the only problems with them are that they sometimes squeek, especially when a little wet or dirty. When they start to squeek, 90% of the time it's the front brake. If I take off the front wheel, run an alcohol-soaked rag between the pads, everything is okay. Also on a hard turn, they will just barely rub a little, again I think it's the front, but no biggie.

As far as performance goes, they perform really well. I mean they can stop fast, and a tandem carries some pretty good momentum. The feel certainly isn't the same as with wheel rubbers, but once you get used to them, they will feel normal. Now, when I jump on my half bike, I find I have to put more beef into braking than with our tandem.

Bottom line; something isn't performing up to par. I wonder if Avid has changed their pad formulation. It's important that when you have problems like this, you clearly convey them to not only your LBS, but directly to Avid. That's how a manufacture learns and develops better products. If many are having the same problem, then it needs to be addressed or the product goes away, cause there's always someone coming with a better mouse trap.

From reading the whole post, IMO they are still not setup correctly. If you are squeezing the rear lever and it is traveling all the way to the bar, then your cable tension needs to be tightened. There is the possibility it is a defective caliper, but that is still a lot of travel for your 105 lever if the cable tension is adjusted properly. I would readjust myself and see what happens. Run your barrel adjuster almost all the way in, then tighten the cable on the actual caliper. Use the barrel adjuster to then dial in cable tension to your liking. I have built quite a few bikes at my shop with a lot lower end mech. disc brakes than BB7 and have never had a problem like you are experiencing. I am putting BB7's on my new commuter because of the performance level that most of them run at. Good luck with everything though, keep us posted.

My .02, since I am one with the bike with no brakes.

Poor cable routing, and possibly running full housing. The cable is very slack when not engaged.

I am going to give it another week and then see what its like then. I will re-adjust the brakes towards the end of th week, but I doubt I will see much improvment.

Reason I say the cable and housing is the front brakes are sweet, no problems, but also very little cable and housing.

Thanks,
Paul

could be the housing...if it is full length to the back


these brakes are so easy to adjust...I am now guessing improper lever
check the specs again on your lever throw and the bb7 requirements


so..try nokon. nokon will be rock farking solid. i run nokons on my
other bikes. the nokon setup is pow-er-ful.

if the avids still run like
cheeze after nokons then ....nah it's impossible for them to be junk after nokons...

I am curious if this is the problem area, plus the bend under the BB and the bend at the brake hood. I am a bit frustrated on this bike, the whole reasone I wanted this bike was the brakes and they are the biggest disappointment. I had paid for and ordered this bike in Jan of this year, and didnt get the bike until early April (4/17).

If I had to lock the bike down with any speed and I wasnt on my guard the bike would throw me over the bars because the HUGE braking difference in the front and rear.

Do you think full housing will solve the problem?

I am curious if this is the problem area, plus the bend under the BB and the bend at the brake hood. I am a bit frustrated on this bike, the whole reasone I wanted this bike was the brakes and they are the biggest disappointment. I had paid for and ordered this bike in Jan of this year, and didnt get the bike until early April (4/17).

If I had to lock the bike down with any speed and I wasnt on my guard the bike would throw me over the bars because the HUGE braking difference in the front and rear.

Do you think full housing will solve the problem?
Full housing isn't going to solve your problem, its only going to put more resistance on the cable. Your front brake should do the majority of the work in stopping, so being able to throw you over the handlebars doesn't really mean anything for the rear only that your front has mucho power. If you use only your rear brake, how much stopping power do you get out of it?

Looks obvious - the bend in the housing as it goes into the brake caliper is far too acute. What you could do is skip the first cable stop and route the cable differently by using full cable housing as far as the next cable stop. Just fix the cable housing to the upper part of the chainstays with zip ties. Or just use full cable gousing but get some of those Avid full metal jackets.

The cable routing into the caliper is critical with Avid mechanicals.

That frame just isn't suited to Avid mechanical discs the way it is. If it was sold to you with the Avid mechanicals then I'd get in touch with the manufacturer or the shop that sold it to you.

I just saw a review of that bike in a British cycling mag and they didn't mention any problem with the rear brake. The only difference I can see compared to yours is that the cable housing passes over the top of the chainstay instead of under it as is the case with yours. You could swap it over and try that.

Full housing isn't going to solve your problem, its only going to put more resistance on the cable. Your front brake should do the majority of the work in stopping, so being able to throw you over the handlebars doesn't really mean anything for the rear only that your front has mucho power. If you use only your rear brake, how much stopping power do you get out of it?

I agree, but when the bike has a front brake that is 4x as strong as the rear and the rear levers hit the bar then things are different. I know 70% of the power is the front but when the rear is pitiful to start then what. I have dura-ace and 4 other shimano (Ultegra, 105's) brake set ups that blow this away.

I was at the shop today for other reasons and discussing the brakes or lack there off. Another issue is the guide under the BB is not lined up with the cable routing, and this is on all the Portlands. The guide points in a direction that is at least 30 degrees off of the cable routing, so the cable is drug out of the slot and across the ridge if that makes sense.

I may shoot a pc of housing from the BB to the brakeset. If I can get all the slack out of the cable at rest I may solve most of the problem. The cable slack at rest hangs limp, it takes more than 1/4 of the pull of the 105 lever to just tighten the slack up before engagment.

I like the bike overall, its a nice addition to the stable. Just hate the rear disk is so poor.

Thanks
Paul

I'm sure you will get it figured out eventually. Without actually having the bike in hand, it is kind of hard to help you fix it. We have a Portland in our shop on display, and I put it on the stand today to take a look at the rear brake, and it seemed to work flawlessly. I would take it back to the shop and ask them to fix it. If they can't fix it, they should take the bike back. My shop doesn't do returns on bikes, but if a customer has a dilemma with a new bike for some reason and we can't fix it, we will exchange it for another bike.

I agree, but when the bike has a front brake that is 4x as strong as the rear and the rear levers hit the bar then things are different. I know 70% of the power is the front but when the rear is pitiful to start then what.

Almost always you should be using the front brake alone. Read this article for an explanation:
http://sheldonbrown.com/brakturn.html

Also this one:
http://draco.acs.uci.edu/rbfaq/FAQ/9.17.html

If Sheldon Brown and John Forrester agree on something that's good enough for me.

I know all my power comes from the front just the point of a bike with poor to no rear brakes. When the lever hits the bar, and you have to move your fingers out of the way or they will be pinched type of complaint. I am commuting with the bike, in the hills of Asheville NC and dealing with it, and overall am pleased with the bike.

Sort of like saying all your car's braking power comes from the front, why have rear brakes? We know that its a fact, all the power comes from the front on cars, motorcycles and bicycles alike. So why do makes put them on?

On a car it would be less noticble since you only have 1 pedal.

We have a Portland in our shop on display, and I put it on the stand today to take a look at the rear brake, and it seemed to work flawlessly. I would take it back to the shop and ask them to fix it. If they can't fix it, they should take the bike back. My shop doesn't do returns on bikes, but if a customer has a dilemma with a new bike for some reason and we can't fix it, we will exchange it for another bike.

My shop is good that's not the issue. They are trying to help, and do agree on the poor braking.

I am curious about your Portland though. If you can take a look at it again and see if the cable is slack in the rest position. One of the mechanics yesterday suggested pre bending the cable at the BB. I see that as a possible improvemnt in the whole scheme, I also think that the cable guide is a problem plus the sharp "S" bend at the brake itself. It all comes back to poor routing by Trek.

Almost always you should be using the front brake alone. Read this article for an explanation:
http://sheldonbrown.com/brakturn.html

Also this one:
http://draco.acs.uci.edu/rbfaq/FAQ/9.17.html

If Sheldon Brown and John Forrester agree on something that's good enough for me.

If there's loose gravel on an asphalt road (which you get a lot in towns and cities) then braking with front only is very unnerving.

If you're loaded up going down a 25% gradient you need both brakes.

Just a couple of instances where a bike like the Portland should be very much at home.

The guy just bought a new bike and the brake isn't working properly, that's the issue, not his braking technique!

My shop is good that's not the issue. They are trying to help, and do agree on the poor braking.

I am curious about your Portland though. If you can take a look at it again and see if the cable is slack in the rest position. One of the mechanics yesterday suggested pre bending the cable at the BB. I see that as a possible improvemnt in the whole scheme, I also think that the cable guide is a problem plus the sharp "S" bend at the brake itself. It all comes back to poor routing by Trek.
Nope, the cable doesn't have any slack in the rest position on the Portland at my shop.

Something funny happened on the way to the shop :)

I lead a ride this morning for beginers, and to keep from being seen as intimidating riding a race bike in race colors I brought the Portland out, I would have commuted but strong storms in forecast for the afternoon. As I was waiting to ride I was messing around with the bike on the roof top and started pulling at the cable and messing with the housing. The rear braking improved on the ride! Got somewhat decent....

Still slack exists in the cable. I dropped the bike off at the shop for them to work on once again. I was told there would dig into the levers and housing stop points and see if there is a snag, also pre-bend the area under the BB and maybe file on the poor guided BB cable routing bracket. Might even test a pc of full metal jacket in a spot or 2 and straighten out the "S" bend at the brake.

I will pick it back up tomorrow, lets hope this fixes it.!

On another note, any good suggestions for a 5am headlight that works and is inexpensive?