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  1. #1
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    Do disc brakes benefit from break-in period?

    The new Santana I test rode today (another thread) was equipped with Santana's 10" rear disc brake. I found it sluggish and having poor stopping power. I much prefer the response of the V brakes. I am even considering retrofitting with my old Arai drum brake if we buy the bike.

    Will the brake's performance improve after some miles of break-in?

  2. #2
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    Disc brake pads need to be bedded in, check the manufactures instructions, or there are plenty of guides on-line for how to do this, for example http://www.bikeradar.com/gear/articl...ke-pads-31337/

  3. #3
    hors category TandemGeek's Avatar
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    Quote Originally Posted by jrl@pobox.com View Post
    Will the brake's performance improve after some miles of break-in?
    Yes, it will improve significantly...

    Disc brake pads and rotors when new do not work well at all. It takes anywhere from a few to dozen's of brake application cycles to bed-in the brake pads and rotors, depending on how steep the terrain is where you are riding and how aggressively the brakes can be used. Owners will quickly recognize when the brakes begin to "bite" as there will come a point during the break-in process where there will be a dramatic change in braking effectiveness.

    New brake pads, when installed on seasoned rotors, will also need bed-in time.

    I'm somewhat disappointed that your dealer did not offer this critical information, but also not surprised.

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    Thanks. So would you suggest sticking with a single front V-Brake and the 10" rear disc as equipped now? We live in a very hilly area, and are a 315-320 lb team.

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    hors category TandemGeek's Avatar
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    Quote Originally Posted by jrl@pobox.com View Post
    Thanks. So would you suggest sticking with a single front V-Brake and the 10" rear disc as equipped now? We live in a very hilly area, and are a 315-320 lb team.
    Unless the rear brake becomes noisy and is irritating, I would leave it as is. The front rim + rear disc is a nice match for hilly terrain, and now that newer Shimano integrated levers worth with the V-brakes without the use of adapters it's really hard to find fault with them at all.

  6. #6
    Clipless in Coeur d'Alene twocicle's Avatar
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    Part of the problem with soft disc brakes on a Santana may be attributed to the longer, more convoluted cable routing required to reach the chainstay mounted caliper. The worst part of the routing is from under the rear bottom bracket and then to the upper side of the chainstay. My early experiments with increasing cable tension, adding helper springs to the disc caliper, etc, were some attempts to improve the brake response in this type of setup. Even with some of the stiffest casing (Nokon) and wire, I was never able to improve the rear brake feel more than perhaps 85% of a "straight run" cable setup to a seatstay mounted disc caliper (as mounted on a Co-Motion, Calfee, etc). In spite of this deficiency, the mechanical caliper with 8" (203mm) rotor on our Santana proved completely adequate for our needs and operated without any breakdown incidents. Reliability was the primary trade off I wanted, over a potentially better performing but problematic and maintenance headache hydraulic setup.

    Suggestions other than what has already been stated above:
    - using the best quality cable casing and wire (such as Jagwire Slick Stainless preferred over Teflon coated) is the first step.
    - rotors and pads must be kept free of lubricants. Avoid over spray from chain, and never touch without clean gloves (avoid skin oils). The demo tandem you rode may have had some contaminant (oils and/or shipping grease) present on the rotor and not visible to the eye. If the pads have been contaminated the only way to fix that is to replace them.
    - changing out default mfr "orgainic" pads to sintered, metalic pads is a known performance improvement that many people implement to achieve the ultimate caliper-to-rotor "bite". Under very heavy usage, sintered pads also last much longer than organic.
    Last edited by twocicle; 11-11-12 at 11:39 AM.

  7. #7
    PMK
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    I agree with twocicle comments about the disc and pads must be clean. Even soap residue from washing will degrade performance.

    As for replacing contaminated pads, I do not subscribe to that approach and will often clean a set of pads by "popping" them out and washing with brakleen. I'll also often scrub the disc with the wheel mounted with a cloth dampened in brakleen. For us, this brings back crisp well controlled and effective brakes. Contamination has ranged from soap from washing to road dust, brake pad wear and even when I'm lazy and use 90 wt gear oil on the timing chain that gets onto the disc during a ride.

    Best of luck with it.

    PK
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  8. #8
    Clipless in Coeur d'Alene twocicle's Avatar
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    Quote Originally Posted by PMK View Post
    I agree with twocicle comments about the disc and pads must be clean. Even soap residue from washing will degrade performance.

    As for replacing contaminated pads, I do not subscribe to that approach and will often clean a set of pads by "popping" them out and washing with brakleen. I'll also often scrub the disc with the wheel mounted with a cloth dampened in brakleen. For us, this brings back crisp well controlled and effective brakes. Contamination has ranged from soap from washing to road dust, brake pad wear and even when I'm lazy and use 90 wt gear oil on the timing chain that gets onto the disc during a ride.

    Best of luck with it.

    PK
    This is true and a case where bike cleaning is a detriment. Have you tested the non-clorinated (less toxic) versions of Brakleen?

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    This all sounds like a pain to me. Plus the risk of bending the damn rotor on something in my garage.

    Wouldn't I be better off with 3 brakes - two V-brakes, and my Arai drum? That sounds like more stopping power and more reliability.

  10. #10
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    Quote Originally Posted by jrl@pobox.com View Post
    This all sounds like a pain to me. Plus the risk of bending the damn rotor on something in my garage.

    Wouldn't I be better off with 3 brakes - two V-brakes, and my Arai drum? That sounds like more stopping power and more reliability.
    I clean my rotor with alcohol and a rag every few hundred miles just as I clean rims to work with rim brakes. I have a rear disc brake with a front V brake and like the disc.

  11. #11
    PMK
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    We run the same Avid BB7 style brakes on both our road tandem and off-road tandem. The off-road discs take a beating from debris, and ruts. Your garage is hopefully a nicer environment than the axle deep slop we have put these brakes through.

    Ultimately, you should ride what inspires you and provides confidence.

    As for more stopping power, it is often discussed here. I do know that if we get caught in the rain the brake performance is still pretty good, in the dry it could be considered too much for where we live and ride.

    PK
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  12. #12
    PMK
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    Quote Originally Posted by twocicle View Post
    This is true and a case where bike cleaning is a detriment. Have you tested the non-clorinated (less toxic) versions of Brakleen?
    Non-chlorinated vs Chlorinated, I prefer to buy the chlorinated, but will use the other if needed. Often I just wipe down the discs with a not even damp cloth with wash lacquer thinner.

    As for a clean bike being a detriment,...not going there.

    PK
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  13. #13
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    Quote Originally Posted by jrl@pobox.com View Post
    This all sounds like a pain to me. Plus the risk of bending the damn rotor on something in my garage.

    Wouldn't I be better off with 3 brakes - two V-brakes, and my Arai drum? That sounds like more stopping power and more reliability.
    If that's what you think will work for you, go for it. I have one of my tandems equipped with an Arai drum brake and have never used it while riding. As someone that has drum-brake equipped half-bikes, I love the technology and prefer it over my disc-brake equipped Cannondale half-bike. I love disc brakes on a car, but don't much care for them on a bicycle.
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  14. #14
    Senior Member mtbikerinpa's Avatar
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    In the event of a long cable run having compressive issues hindering performance, I would look into a hydraulic caliper option. The hose and hydraulic fluid would be almost unaffected by the distance unlike cables. Nevertheless, the company made it with that setup so it must have been good enough to please someone(since they are a reputable company).
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    This helped me out cause I was wondering the same thing my breaks are a bit sluggish and soft now but just road a few times yesterday not enought for a full proper bed in process
    if after say a few dozen breaking cycles
    what should I look for is it the cab
    e that might need to be adjusted or is it possible that I would have to tighter the adjustment at the caliper or disc area ?
    Or more up near the break lever ?

  16. #16
    Uber Goober StephenH's Avatar
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    First off, zombie thread, it's a couple of years old now, so hopefully, the original poster has got his new brakes worked out.
    I've read the instructions on breaking in brakes and never could tell a lot of difference in the performance during the process. Mushy brakes has always been a matter of adjustments. I have also noticed that a mechanic can adjust brakes on the rack so they feel right (ie, stop a freely-spinning wheel just fine) but lack braking power with weight on the bike.
    "be careful this rando stuff is addictive and dan's the 'pusher'."

  17. #17
    Clipless in Coeur d'Alene twocicle's Avatar
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    A couple weeks back I was adjusting our rear TRP disc caliper to get a firmer feel. After a number of repeated full-on lever clampdowns, things started to get mushier and mushier. For a minute I thought maybe I broke something with the hard clampings, then PRANG goes the brake cable... pulled right out of the daVinci cable splitter. OOPS.

    Luckily this happened while the tandem was on our workstand and not descending some wicked hill. Seems it was mechanic error (me) for not fully tightening the cable splitter set screws - or at least rechecking them after some initial use. After resetting the brake cable splitter, have not managed to repeat the failure. I was always a bit leery of overtightening the screws and stripping them or the splitter, but after pulling the cable out, decided to really clamp down on it.

    Having a splitter on a brake cable has always made me a bit nervous. Moral of the story - check and recheck those set screws!
    Last edited by twocicle; 04-06-14 at 12:25 PM.

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