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Author Topic: Brake help  (Read 1965 times)

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Offline JohnnyB

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Brake help
« on: February 23, 2009, 08:34:21 PM »
So, being new to the world of disc brakes I never knew how they were supposed to perform.  I thought mine were fine  until I rode Greggs rig and realized that I need to fix my brakes! LOL
 
How do I adjust them to make them stop better?  My front brake seems to be fine, but my rear doesn't really respond too well.  Can I replace the pads?  Or is it more likely to be the disc itself?
 
Not that I intend to be jamming on my brakes all the time, but there have been a few instances where I barely made the stop or else I would be gator bait.  It would also be nice to restore my confidence in my ability to stop when I need to.
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Offline silentneko

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Re: Brake help
« Reply #1 on: February 23, 2009, 09:05:33 PM »
what kind of brakes are they? I have bb5's and it took me a while to get them adjusted right. I also had contaminated pads which made them grip like they were buttered up or something.

Offline catman

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Re: Brake help
« Reply #2 on: February 23, 2009, 10:48:03 PM »
If I remember correctly the Frankenbike has Avid BB5's. I can only speak for the BB7's but I'm thinking they similar.You have two red knobs to move each pad closer or further away from the rotor. That is the easy way to test and adjust. Look down the rotor and see how much of a gap you have between the rotor and pads(also check your pads to see if they are trashed) if there is a good size gap try turning in the red knob on the same side until the gap is smaller but not dragging. Same goes for the other side. This may help quite a bit. It will affect how your lever feels and how far it travels. You can also take up some slack at the caliper by loosing the cable clamp and pulling the cable towards the rear of the bike just a bit. You can do the same at the brake lever. Worse case you'll have to shim the caliper or clean the mounting tabs so that it's sitting on the frame correctly. Avid mechanicals can be a pain in the ass to get just right since only one pad travels inward.Also make sure you're not spraying chain lube on the brake pads.
 
Make sure you're comparing apples to apples. Did the bike you ride have hydraulic brakes? You'll never get those BB5's to perform like hydros.
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Offline JohnnyB

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Re: Brake help
« Reply #3 on: February 24, 2009, 08:15:38 AM »
If I remember correctly the Frankenbike has Avid BB5's. I can only speak for the BB7's but I'm thinking they similar.You have two red knobs to move each pad closer or further away from the rotor. That is the easy way to test and adjust. Look down the rotor and see how much of a gap you have between the rotor and pads(also check your pads to see if they are trashed) if there is a good size gap try turning in the red knob on the same side until the gap is smaller but not dragging. Same goes for the other side. This may help quite a bit. It will affect how your lever feels and how far it travels. You can also take up some slack at the caliper by loosing the cable clamp and pulling the cable towards the rear of the bike just a bit. You can do the same at the brake lever. Worse case you'll have to shim the caliper or clean the mounting tabs so that it's sitting on the frame correctly. Avid mechanicals can be a pain in the ass to get just right since only one pad travels inward.Also make sure you're not spraying chain lube on the brake pads.
 
Make sure you're comparing apples to apples. Did the bike you ride have hydraulic brakes? You'll never get those BB5's to perform like hydros.

The bike I rode did have hydro's on it..and I know my mechanicals will never be like the hydro's, but it made me realize that there is definitely something off with my breaks.  I am going to do some adjusting to see what I can come up with...I appreciate the helpful info.
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Offline KRUNNCHERO

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Re: Brake help
« Reply #4 on: February 24, 2009, 09:20:46 AM »
Just an FYI. Those BB5s are used and haven't had new pads since I bought them. So if you plan on sticking with them; I would look into checking the rear brake cable, the rear brake's routing to make sure it is smooth, and perhaps new sintered pads ($20 for the rear).
 
Kris
 
P.S. Gregg does have hydros - carbon Hayes strokers? if I remember correctly from Saturday.
« Last Edit: February 24, 2009, 09:32:57 AM by KRUNNCH »
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Offline silentneko

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Re: Brake help
« Reply #5 on: February 24, 2009, 11:34:04 AM »
ok here is my bad attempt at a how to write up. if it sounds like jiberish......well sorry, but this is how I got my BB5's working like they should.
 
first you gotta take care of the pads before you adjust them, so take off the wheel and pull the pads out. now take a piece of sandpaper (100-120grit) and wrap it around a FLAT piece of wood or something and sand the surface of your pads. make sure they are flat and only do enough to take a thin surface layer off. Next soak them in a container of rubbing alcohol for a few minutes then let them dry.
Whipe your brake rotor with some rubbing alcohol to get all the contaminates off. reinstall your pads and then your wheel.
now loosen up the brake caliper just enough so you can move it (the 2 allen bolts that hold it on). Adjust the plastic wheel so that the rotor is somewhat centered in the caliper body.
For this part I had the bike upside down. press the brake lever ( used my foot) so that the brake is gripping the rotor well. now tighten the 2 allen bolts that you previously loosened.
Twist the plastic brake pad knob a few clicks until the pad no longer rubs and your caliper is now adjusted and squared to the rotor.
 
After all that you might need to adjust your cable, but that parts easy.
One more thing I had to do was true up my rotor cause it had been slightly warped from a few wrecks. all I did was spin the wheel as I looked at the caliper and when I saw where it was wavy I took a screwdriver and put it through the rotor and with just a tiny bit of pressure it bent right back where it needed to be
 
I hope some of this made sense and helped, good luck.

Offline treadlight

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Re: Brake help
« Reply #6 on: February 24, 2009, 11:44:16 AM »
I thought mine were fine  until I rode Greggs rig and realized that I need to fix my brakes! LOL

Johnny--don't get me wrong this is unfair comparison, your mechanical brakes might be doing what it is supposed to do. It will never outperform Gregg's hydro with respect to how sensitive it will respond when you squeeze the lever. ;)

Offline JohnnyB

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Re: Brake help
« Reply #7 on: February 24, 2009, 12:32:40 PM »
Silent - the write up made perfect sense!  and thanks I will be u sing that to quide me through it tonight.

Tread - yeah I know.  Gregg even told me that when he let me try them out.  But my brakes always felt a little mushy to me considering they should have been upgrade from V brakes...I know they won't respond like greggs but they should at least respond..llol
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Offline silentneko

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Re: Brake help
« Reply #8 on: February 24, 2009, 12:35:21 PM »
Quote
Johnny--don't get me wrong this is unfair comparison, your mechanical brakes might be doing what it is supposed to do

they might be, but with my experience I leaned that with the BB5's if they aren't adjusted perfectly then they wont grip worth a dang. now that I have mine just right they work pretty good. wouldn't mind moving up to BB7's, not interested in hydro's, but the BB5's do the job nicely for now.

Offline Harvey

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Re: Brake help
« Reply #9 on: February 24, 2009, 01:19:19 PM »
One more thing I had to do was true up my rotor cause it had been slightly warped from a few wrecks. all I did was spin the wheel as I looked at the caliper and when I saw where it was wavy I took a screwdriver and put it through the rotor and with just a tiny bit of pressure it bent right back where it needed to be.
A crescent wrench adjusted to just a bit wider than the rotor works really for this.

Offline Gough

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Re: Brake help
« Reply #10 on: February 24, 2009, 11:56:52 PM »
if your rear brake cable is routed through a very long housing it will be very mushy. if you can reroute the front derailler on a long housing and use the cable stops for the front derailler to route the rear brake housing. removing a foot or so of the housing will improve the feel of the brakes. Avid also sold a steel tube system for those brakes, not sure if it is still availlable.
 
adjust the inner pad so it is very close to the rotor, move it in till it touches, then back off a couple of clicks, then take up the cable slack to get the outer pad closer to the rotor, don't go tighter than comfortable for your hands to pull lever.

Offline JohnnyB

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Re: Brake help
« Reply #11 on: February 25, 2009, 01:46:53 PM »
So I took some time this morning to mess around with the brakes.  I took out the pads and used some emery boards to sand them town a little bit to make them more flush.  While those soaked in some alcohal I took a cotton ball and cleaned the disc with some alcohal as well.  I dried off the pads and put them back in and used a star key to adjust the inside pad so it is closer to the disc and I also pulled the cable a little tighter.  From the 2 feet I have on my apartment balcony to move the breaks felt a little better.  But I'll need to get out and ride to see just how much.

Just wanted to give an update and also let you all know this thread walked me through it and made it much easier.

So, thanks again.

JohnnyB
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Offline JohnnyB

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Re: Brake help
« Reply #12 on: February 25, 2009, 01:48:04 PM »
Also, gough you mentioned the problem with the cable itself.  Would it help if I backed the cable out of the housing and applied some grease or oil?
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Offline KRUNNCHERO

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Re: Brake help
« Reply #13 on: February 25, 2009, 02:16:44 PM »
I would say more than the importance of the brake cable length is whether it is allowed to flex or not. Grab any mechanical brake lever and watch the housing flex. Removing distance does inherently reduce the capacity for it to flex, but it is not the only variable in the squishy feeling. My brake housings on my DH rig are long as all get out to adjust for 8.5" of travel and a 46.5" wheelbase, but I did it so that they have very little room to flex when I compress the brake lever. That being said, I would take my BB7s over BB5s any day of the week. I used those BB5s for probably 3 years and never was satisfied with how the rear stopped. The front always stopped perfectly, but that rear just sucked.

If I remember correctly, the housing/routing going to the back of Johnny's hardtail is probably as short as its going to get. When we were installing the rear, there was some sticiton when we compressed the rear brake lever to when the pad actually contacted the rotor.
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Offline JohnnyB

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Re: Brake help
« Reply #14 on: February 25, 2009, 02:35:59 PM »
Kris, that is something I noticed right off the bat.  The front break works like a charm but the rear is not so great.  I've just been adjusting my riding style to use the front brake as a primary and the back more so as a help to the front.  It's probably better right now for me that the back isn't too grabby, that way I am not able to slide around turns or down steep drops...not that i really like using the brakes much anyway.
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