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  1. #1
    Senior Member bryroth's Avatar
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    Replacing brake pads - Does it require an Engineering degree?

    I am ready for the scorn this might lead to, but if someone could tell me what I am (currently) doing wrong I can get some sleep tonight.

    I bought a used cyclocross bike with road tires. It has Avid 4 shorty cantilever brakes. The brakes were glazed over. I am a noobie so this is what I did:

    1. Got gouged by local bike chain when they installled new Shimano brakes. 2. The brakes were still iffy, so I bought some Kool Stop Supra 2 brakes, based off of loads of reviews from this forum. 3. I accidentally bought the direct pull kind. 4. Sold direct pull kind on eBay. 5. Reinstalled the shimano brake pads myself. 6. Considered buying earplugs and life insurance. 7. Bought a second pair of threaded Kool Stop Supra 2. 8. Tried to install them last night, but the Kool Stops are too fat to fit on the bike. 9. Reinstalled the shimano pads. 10. Got frustrated, drank 4 beers while my girlfriend went to sleep and watched re-runs of the Tick through the spokes of my upside-down bike. 11. Overslept for work this morning.

    So I'm like 4 weeks into trying to change my brake pads, and I'm feeling a little discouraged over here. I just want the Kool Stops on my bike. I worked in a machine shop for years, yet these four little ******** brake pads seem to have gotten the best of me.

    Which Kool Stops am I supposed to install on this bike? Now that I look at it, even the Thinlines even seem like they would be too fat. In fact, the Shimano's only give a little bit of clearance and I'm supposed to be able to put fat tires on this bike.

  2. #2
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    Quote Originally Posted by bryroth View Post
    I am ready for the scorn this might lead to, but if someone could tell me what I am (currently) doing wrong I can get some sleep tonight.

    I bought a used cyclocross bike with road tires. It has Avid 4 shorty cantilever brakes. The brakes were glazed over. I am a noobie so this is what I did:

    1. Got gouged by local bike chain when they installled new Shimano brakes. 2. The brakes were still iffy, so I bought some Kool Stop Supra 2 brakes, based off of loads of reviews from this forum. 3. I accidentally bought the direct pull kind. 4. Sold direct pull kind on eBay. 5. Reinstalled the shimano brake pads myself. 6. Considered buying earplugs and life insurance. 7. Bought a second pair of threaded Kool Stop Supra 2. 8. Tried to install them last night, but the Kool Stops are too fat to fit on the bike. 9. Reinstalled the shimano pads. 10. Got frustrated, drank 4 beers while my girlfriend went to sleep and watched re-runs of the Tick through the spokes of my upside-down bike. 11. Overslept for work this morning.

    So I'm like 4 weeks into trying to change my brake pads, and I'm feeling a little discouraged over here. I just want the Kool Stops on my bike. I worked in a machine shop for years, yet these four little ******** brake pads seem to have gotten the best of me.

    Which Kool Stops am I supposed to install on this bike? Now that I look at it, even the Thinlines even seem like they would be too fat. In fact, the Shimano's only give a little bit of clearance and I'm supposed to be able to put fat tires on this bike.
    First of all you must keep your patience, as soon as you get frustrated you have lost. Though getting angry does have it benefits when you're trying to pry loose a ball joint or something off of a POS Chevy truck, but when it comes to detail oriented stuff you just have to be patient.

    I cant help you too much, because my knowlege on different bike parts is limited. But if your brakes is anything like the ones I've seen, you should be able to adjust the distance between the pads and the brakes. Sorry I cant answer your problems fully, but I'm sure someone will give you a more direct answer on this forum.

  3. #3
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    Next time you come across glazed brakes you might try to freshen the surface simply by sanding it down some. Use a file if you're concerned about leaving any abrasive on the pads. Clean rims thorougly if there's some contaminant there rather than ordinary use that's causing the glazing.

    Don't quite understand that bit about "kool-stops being too fat".
    First there's usually some adjustability by restacking the spacers to get the pad to sit at different distances to the rim/brake arm.
    If that shouldn't be enough you can always let out a bit more wire, that will also give you some extra clearance. Maybe it'll put you a few mm off the ideal geometry, but that's not something I'd worry about.

    Brake squeal is usually caused and cured with the toe-in angle, more angle - less squeal.
    Some rim/brake/pad combos require more than others. Have a Mavic ceramic that kept squealing pretty much no matter what for what felt like an endless break-in period. But even that one quieted down eventually.
    Based on the glazing and squealing it once again seems like you might benefit from cleaning your rims.

    Brake clearance vs. tire diameter isn't an issue, the straddle cable unhooks from one of the arms allowing the brake arms to pivot away in their entirety for wheel insertion/removal. As long as you get the clearance to the rim OK you shouldn't have to worry about the tire.

  4. #4
    Senior Member bryroth's Avatar
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    Thank you very much!

    Someone once told me that unless the wires on the V brakes are at a perfect 90-degree angle from
    each other then it can be dangerous. Is that correct? If I have a little bit of play I'll let some cable out. I already tried the "short" setup with the washers.

    Also, I'm thinking about buying fat tires for my cyclocross bike. Seems like you are saying that even fat tires, like going from a 37 from a 27, will have the same or a comparable size rim? I had assumed that the rim size would increase proportionally.

    Perhaps my problems are solved...

  5. #5
    Senior Member m_yates's Avatar
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    The wire doesn't have to be at a perfect 90 degree angle. In fact, you get more braking force the lower you have the wire set. You can set the pull wire as low as you want until it starts interfering with fenders (in you have them). It gets dangerous if you set the pull wire too high because then most of the pull force acting on the cantilevers is directed upwards rather than inwards towards the rim (which is what you need to stop obviously).

    You should be able to adjust the length of cable to get news pads to fit. You should also visit the park tools website. It has some good instructions on adjusting cantilevers. http://www.parktool.com/repair/readhowto.asp?id=19

  6. #6
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    Quote Originally Posted by bryroth View Post
    Someone once told me that unless the wires on the V brakes ...
    I'm assuming this is a typo, as the first post mentions cantilever brakes. If it isn't a typo be aware that cantis and v-s require different levers (or an adapter) to get the right amount of cable pull to function well on the bike.


    Quote Originally Posted by bryroth View Post
    Someone once told me that unless the wires on cantis are at a perfect 90-degree angle from each other then it can be dangerous. Is that correct?
    Not at all. There are several angles in a canti set up that varies as brakes are activated, pads wear and parts flex, so don't worry about it. There is a "perfect" angle to aim for, but the "spot of optimum performance" is surrounded by a rather wide zone of "perfectly acceptable performance".

    The only proposed danger that I know of is that a low-set straddle cable can get caught in the tire tread and cause an endo if the main brake cable should break.

    Quote Originally Posted by bryroth View Post
    Also, I'm thinking about buying fat tires for my cyclocross bike. Seems like you are saying that even fat tires, like going from a 37 from a 27, will have the same or a comparable size rim? I had assumed that the rim size would increase proportionally.
    Rims come in far less different widths than tires do, and going up or down a size or two usually works just fine.

    See http://sheldonbrown.com/tire-sizing.html for more.

    Short quote:A general guideline is that the tire width should be between 1.45/2.0 x the inner rim width.

    If you flatten out a tire and measure the total width from bead to bead, it should be approximately 2.5 x the ISO width.

    If your tire is too narrow for the rim there's an increased risk of tire/rim damage from road hazards.

    If its too wide for the rim, there's an increase risk of sidewall wear, and a greater risk of loss of control in the event of a sudden flat.


    CX bikes generally have quite good frame/tire clearance, but I'd be more concerned about that than the rim anyhow.

  7. #7
    Senior Member bryroth's Avatar
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    I just learned a lot. Thanks to all for the advice.

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