twoflats

I've been over the videos and have my pads adjusted very, very close to the rotors, but I'm still not getting any decent braking power. FWIW, I'm using SRAM Rival levers and it takes over half of my lever travel before there's any stopping power at all. Even when pulling the lever all the way to the bar, I'm not getting nearly enough power to lock up the wheels. The pads contact the rotor with the slightest pull of the levers, but I get absolutely no stopping power for the first half of the lever pull.

Anyone have a similar experience with the BB7 Road calipers? More importantly, what can I do to get decent braking performance from them (short of installing a Travel Agent to get more cable pull). Would a change/upgrade of pads help (it seems the pads have to be compressed quite a bit before they grab, so maybe a firmer pad would help)?

Thanks in advance,
Brent

bikinfool

What did you do to bed your pads in?

antchen

If you bought the road BB7s then your disc caliper expects the short pull that a brifter like the rival levers would provide. I would rule that out as the cause. You said that the slightest pull of the levers causes contact, which is odd. Maybe your brake cables have stretched?

One more note is that disc pads usually have a bit of "brake-in" time and then they perform better.

twoflats

I'm not sure what you mean, exactly. My understanding that bedding in the pads simply involves using the brakes a bit, including some high speed, heavy braking. I've only got 100 miles or so on the bike since putting the disc brakes on it, and I have noticed some improvement from when they were brand new, but not nearly enough to have any real confidence in the brakes. Is there something else/more I should do to bed in the pads?

twoflats

I installed Jagwire Racer (compressionless) cables with the disc brakes, though I consider it quite likely that the cables are stretchy.

What bothers me the most is that even after initial contact, I have almost no braking power until I've used half of my lever travel. The only meaningful braking power is the second half of the lever travel, and even then, I bottom out the lever before I get what I would consider reasonable stopping power.

I'd like for the brakes to be nearly locked up at half way through the lever's full travel...like I had the cantis set up. In no case do I want to be able to pull my brake lever all the way to the bar. Maybe I'm expecting too much from the disc brakes. :-|

rmac

Did you set the return spring adjustment screw to its maximum?

Sometimes because of the cable drag even this adjustment is not enough. What year are your callipers? In 2008 they increased the force of the return spring so that they open all of the way when released. In earlier version, some people have used helper springs such as these:

https://www.bikeforums.net/showthread...ng+helper+avid

This gives a much more positive feel to the levers and allows better adjustment.

twoflats

I have 2009 calipers. Thanks for the tip about the return spring tension adjustment. This doesn't fix my braking power problem, but it does fix the annoying problem where the pads would drag a bit if I didn't release the lever quickly enough. My cable routing is pretty clean, so I don't really have much cable drag to speak of...the pad dragging I mentioned above happens without any cables attached because my pads are so close to the rotors that unless the outboard pad is fully retracted, it drags.

rmac

Having the pads fully retracted each time allowed me to adjust the pads closer to the rotor so the pads hit the rotor with just a little movement of the brake lever. Good luck!

twoflats

Yeah, my pads are already stupidly close to the rotors...a piece of notebook paper is a tight squeeze between the pads and rotors.

I wonder if they installed the new Teflon coated brake pads in my calipers by mistake. :-\

Are there harder brake pads that I could try? Maybe a ceramic pad? Or a sintered pad? I really think the problem is related to the pads compressing so much before they grab the rotor...something is certainly compressing (or flexing), because I can see the lever/arm on the caliper continuing to move well after the pads have contacted the rotor.

BTW, thanks to all of you who've tried to help.

BarracksSi

Just making sure that they're aligned, too;

I had so-so braking performance from my road BB7s until one of the guys at my LBS really got into it and set it up right. The caliper was actually at a small angle, and he realigned it somehow to make it perfectly straight, which made the pads hit the rotor flat instead of a bit sideways. He also trued the rotor.

The resulting braking is as good as I've ever had on any bike.

bikinfool

That's what I'm talking about; the process of bedding the pad material to the rotor. You're not constantly cleaning the rotor or anything? No chance of having contaminated the pads with lube or something? Are you using resin or metallic pads? Do you have another pair of pads to switch out to see if that's the issue?

I've not used the road versions (mountain versions for 8 years now) so am of limited help with lever travel issues, but it does sound like something is wrong. You're following Avid setup instructions to the letter? You're not using the cable tension for pad adjustment and have the caliper positioned as suggested?

twoflats

I believe the pads sit squarely against the rotors, but I don't have a set of feeler gauges to verify my visual check. This seems like it could cause my poor braking symptoms, too. I'll pick up a set of feeler gauges tomorrow to verify the alignment.

Thanks!

twoflats

Yes, I've followed the Avid instructions to a "T". I've even torn it all down and reinstalled, making sure to follow the instructions perfectly (just in case I'd had a mental fart the previous time(s)). I only cleaned the rotors once after I'd inadvertently bumped into it with my finger while trying to turn the inboard pad adjuster.

Speaking of brake pads...have you tried various types of pads in your BB7s? Are any of the pads "harder" or do any of them offer a less spongy feel?

johnny monsoon

I haven't ever worked with this system (but will, I have some coming from Nashbar in a few days). Anyway, I found that on a cheaper set I once had, there was a wheel release lever to pop the brakes open. It didn't affect how the brakes compressed in the calipers, it just literally spread the caliper activation so it was easier to pull the wheel out. Could that be the case here? It would explain the problem precisely, and I had that EXACT problem before I remembered that I'd failed to flip the wheel release lever closed again.

bikinfool

I've used several different pads; not only Avid offerings but have also used several aftermarket ones in different compositions (from Kool Stop, EBC and Galfer). My favorites are the current version of the Avid sintered pads (and they're easily sourced which doesn't hurt; I liked the Galfers a lot too but harder to source).

Keep in mind when you clean a rotor you might remove the pad material that's bedded into the rotor and essentially are starting over in the bed in process as a result...

You may have glazed the pads a bit, too; try sanding them with a fine grit sand paper in a figure-8 pattern (can try that on the rotor too).

twoflats

Hmm. It looks like the stock pads are the sintered pads...drats! I'd hoped a pad upgrade might be a possible solution to this nightmare.

I cleaned the rotor quite a while back and didn't notice any difference in performance after doing so. I'll pull the pads out to see if anything looks weird, but honestly I'm not sure what a glazed pad would look like.

Again, thanks.

twoflats

I'm not aware of any such release mechanism on the BB7s.

You'll have to let me know how your install goes...and what kind of levers and cables you're using. I swear it seems like more cable pull would completely solve my problem--I wonder if mine are mislabeled MTB calipers.

bikinfool

No, no such release mechanism on the BB7s.

Is road imprinted on the caliper? My latest BB7s indicate "mtn" on the caliper's torque arm...but I'd guess you'd not even get the results you are now with the wrong caliper. Nice thing about mountain levers is they often have leverage adjustments within the lever for further fine tuning; doubt if the Rival levers have that option.

BTW I think the Jagwire Ripcords (think the Racers are simply the road packaged version) are awesome, particularly with full housing runs between lever and caliper...how is your bike setup for housing? Is your problem different from front to rear brake?

johnny monsoon

Well...

If all you need is more pull, you can artificially induce that by pre-activating your brakes. Just tighten up the cable until the brake is active (say to almost your 'halfway point' in the lever pull). Then you're essentially doubling your pull with the same lever. I wouldn't recommend keeping your bike set up like this, but it'll answer some questions for sure. It'll tell you if it is indeed a lever pull issue for sure. If you can't get it to stop at that point, then I'd suspect a faulty build in the caliper. There's just no way even the stretchiest cables could fail to produce a strong enough stopping force. Heck, it takes MORE effort to stop a bike via rim braking than it does for disk braking. So, if you're using the same grade cable, or maybe even the same exact cable, you're gonna stop. I mean, do you think they put high dollar cables on the WalMart bikes that sport disk brakes? They stop just fine...

Sounds to me like your pads are wrong for the caliper. If you can get them to touch but not really compress on the disk that means your caliper is not compressing enough to get the pads seated on the disk. There's only three things that could be wrong. Either you have the cable way too slack (which doesn't seem to be the case), the caliper isn't pushing the 'piston' through it's full sweep, or the pads aren't thick enough and aren't able to be pushed together enough to cause enough friction. I'd go with the latter since I'd have to suspect that road brakes are likely thinner to shave weight and are the easiest component to flub for the folks packing the materials at the plant.

maddmaxx 

Are your cables (housing) tied down really well under the bar wrap. I have found that drop bars with loose housings on the insides of corners will allow the housing to flex and "waste" quite a bit of cable pull. Not so much of a problem on some brakes, but it sounds like you have'nt got much pull to spare.

When exactly do your pads contact the rotor. If you can adjust your inner or outer adjuster wheel in another click without hearing contact on a spinning wheel then your not tight enough.

Try this. With no pull on the lever, adjust the inner adjuster untill you hear a light drag from the brakes. Back off 1 or 2 clicks. Do the same with the outer. Are the brakes stronger?

Getting mechanical discs to work really well is a little bit of art as well as a lot of the instructions.

Hawaiiwrench

I've set up a few of these.
Sounds like you need to re-set/center the caliper so that the fixed pad is not bottomed out.
Back out the outboard pad, and move in the inboard/fixed one the same number of clicks( in relation to the caliper not the bike), then re-align the caliper.
Gap between pads is the same, but you can stop.

neha

I haven't ever worked with this system (but will, I have some coming from Nashbar in a few days). Anyway, I found that on a cheaper set I once had, there was a wheel release lever to pop the brakes open. It didn't affect how the brakes compressed in the calipers, it just literally spread the caliper activation so it was easier to pull the wheel out. Could that be the case here? It would explain the problem precisely, and I had that EXACT problem before I remembered that I'd failed to flip the wheel release lever closed again.

Trekking | Travel Package

BarracksSi

There's no wheel release lever on the BB7 calipers because it's not needed.

twoflats

I've already got the inboard (fixed) pad set as you describe, and the outboard pad is only three or four clicks from being fully retracted. Both pads are one click from constantly rubbing/dragging on the rotor.

The best theory I have so far is that the pads aren't absolutely, perfectly parallel to the rotors. I meant to pickup a set of feeler gauges to measure this, but didn't have time yesterday...maybe today. If that is not the problem, then the the brake pads are just too compressible/spongy, and I'll try to find pads with a harder compound; I've read that ceramic pads are harder than sintered.

rmac

Sorry, but I don't think the spongyness of the pads are your problem. You'll be just wasting your money. If these pads can adequately stop a tandem weighing 400 lbs with riders and gear, I think they should be able to stop your bike. You need to work on the adjustment to get the pads parallel.