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  1. #1
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    Do I really need 2 new brake discs?

    I'm buying a whole new break for my bike. My last mechanical brake somehow fell off.

    Anyway I need a whole new setup I'm told and because some paint has dripped on the front and back brake discs the store I am buying from tells me that I need 2 new brakes.

    Funny because I am only buying ONE break. (The front one).

    So do I really need TWO new brake discs (one for front and back I am told) when I only need to buy 1 front brake?

    On top of that, is a tiny bit of paint going to make the brake not work? I can barely see the paint on the disc!
    Could I just leave it in a tin of paint thinner for an hour and then use it like new?

    Thanks a ton!

  2. #2
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    Not sure exactly what you are reign to. Do you need a new disk or the caliper? A picture of what you are referring to would help.

  3. #3
    Senior Member JonathanGennick's Avatar
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    Are you talking about paint spilled onto the rotor? If your pads have not already scraped it off, then it is probably not on the braking surface. Whatever the case, rotors are steel and I would just remove the paint by scraping it off, or by rubbing with some steel wool. Then wipe down the rotor w/alcohol or hit it with some rotor cleaner.

  4. #4
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    I'm talking about this:

    The guy from the store said that I have paint on this and therefore the brake itself that attaches to this disc to slow it down wont work at all. He also wants to sell me TWO of them despite the fact that I am only buying ONE break, (the front one). He says that I need 1 for each wheel and that they sell them in pairs 1 + 1 = 2. One for front and back when there is only 1 per wheel and I only am buying 1 brake... for the front.

    So to me, it sounds like a bit of a scam. That he is trying to pilfer 50€ out of me that I don't have to pay. Can I just put the metal disc into a small container of paint thinner and if there is any paint, it'll just come off without damaging the actual disc itself?

    I don't want to have to spend 165€ as opposed to 115€...

    Thanks a lot for your help, sorry that I don't know all the technical terms.

  5. #5
    Senior Member Monster Pete's Avatar
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    You should be able to just remove any paint on the disc with a bit of paint thinner on a rag. If you've used the brake at all, paint on the braking surface should have been scraped off by the pads and any remainder will just affect the appearance. Seems to me like they just want your money. Before you take this guy's word for it, find a safe place to test the brakes for yourself. Ride at normal speed and give the front brake a squeeze as usual. I think you'll most likely find that it works just fine.
    I've got a bike, you can ride if you like it's got a basket, a bell that rings and things to make it look good- Pink Floyd, 1967

  6. #6
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    What disc brake set up do you have? 4 bolt discs have not been made / used for 10+ years. think you need to find a new LBS if you are not happy with them, as you have lised your costs in €, take it you are in Europe somewhere, there are plenty of good mail order shops from the UK, France & Germany, which ship the the rest of Europe to choose from, and they will sell single rotors, or ebay.

  7. #7
    Senior Member JonathanGennick's Avatar
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    You're talking about the brake (not "break") rotor. I agree with Monster Pete. Any paint on the braking surface should have been scraped away by the pads. Whatever paint is left, just scrape it away using steel wool or sandpaper. Clean the rotor using isopropyl alcohol.

    Possibly you will need new brake pads. The paint might have contaminated your pads. Those aren't so easy to clean. Test the brake as Monster Pete suggested. If it stops you like it should, then no worries.

  8. #8
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    Nah guys. I don't have brakes already. I'm buying the whole setup. The metal discs, as I posted a picture of. The actual brake clamp itself and the handle for squeezing the brake.

    So I cant test it. The only thing with paint on it was the metal brake disc.

    Sounds like I don't need the discs, just the brake and the handle.

  9. #9
    coprolite fietsbob's Avatar
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    You Broke your Brakes , which is a tough Break.

  10. #10
    coprolite fietsbob's Avatar
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    So you already had a disc Brake system on your bike already ?

    Frame has to be made to have the mounting tabs on it already , you should realize.



    My last mechanical brake somehow fell off.
    I take it you ignore all maintenance of your bicycle..
    Last edited by fietsbob; 08-08-11 at 11:20 AM.

  11. #11
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    Quote Originally Posted by Kutittaa View Post
    I'm buying a whole new break for my bike. My last mechanical brake somehow fell off.
    Ok, you need a new brake setup. One setup (rotor, caliper, lever) for the front wheel? Please confirm.

    Quote Originally Posted by Kutittaa View Post
    Anyway I need a whole new setup I'm told and because some paint has dripped on the front and back brake discs the store I am buying from tells me that I need 2 new brakes.
    If you have a functional rear brake setup that has paint on the braking surface of the rotor, all you need to do is remove the paint from the rotor and possibly change pads if they're contaminated.


    Quote Originally Posted by Kutittaa View Post
    Nah guys. I don't have brakes already.
    Huh? You mean you don't have a front brake, or any brake? Presumably you have the rear brake with paint on the rotor, and you can test that.

    Quote Originally Posted by Kutittaa View Post
    Sounds like I don't need the discs, just the brake and the handle.
    You need two discs, one for each wheel. If you already have one, then you only need one more. If the one you already have has paint on the braking surface, remove the paint as described above. If you use a solvent to remove the paint, make sure you remove any solvent residue with alcohol or brake cleaner.
    Quote Originally Posted by carleton
    WTF is a "Fixie"?

  12. #12
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    Gosh this is hard.

    I have NO break system at all. I just have the 'rotors'. The metal disc that I showed a picture of. That's all I have. I have no brakes. 0 Brakes lol! No front, no back and no static break when you go to pedal backwards. My bike is brakeless (lmao!).

    All I have are the rotors. 1 front, 1 back.

    I want to buy ONE break setup. The lever + cord, the caliper (actual break system that squeezes the rotor). I DON'T want to buy new rotors. (The metal disc things LOL) gosh I really am a noob, it's like everyone speaks a different language here haha!

    This guy is trying to sell me 2 rotors on top of what I said I need up there. My question was, can I just dip them in some paint thinner and the paint comes off the rotors. (They barely have any paint on them at all anyway!)

    So no. I cant test ANYTHING because I don't have ANY brakes at al. If I rode down a hill, I'd die because I couldn't stop myself. Which is why I am buying a new brake.

    Yes I had a brake but it's gone, it fell off while I was biking through the forest, I know it sounds weird but I swear it's the truth! The bike was brand new from Australia, I paid well to have it taken to Finland, I don't want to have to send it back. So basically I am getting a new brake setup from here.

    The guy wants to sell me 2 rotors. They're 25.95 each. Which is approximately: $35 USD ea. | 22 pounds | $35 AUD | or 2 874 Japanese YEN. (Hahahahhaa!!)

    Ok so now I hope we are all on the same page.

    With this new caliper that I will be buying, the part that actually squeezes the rotor. Will it be compatible with my old rotor? I don't think the brand of brake will tbe the same. So will it match the rotors I already have? When I look around in a store all the rotors look more or less the same size and make, so can I adjust the caliper a little if I find that the rotor is too small/wide or will I have to buy a new one?

    At this stage I think I have established that unless that is the case, I don't need 2 rotors and I can save myself 52.

    Thanks for all the help so far and for bearing with me.

  13. #13
    Senior Member coldfeet's Avatar
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    If you are buying a disc brake, then it comes with the rotor, it's included, ( usually ) I've only ever seen them sold individually, not as front and rear pair. So, if you just want one working brake, you only have to buy one. I would recommend having front and rear though, but it's your choice.

  14. #14
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    Yep, cf is right. Normally, when you buy a disc brake, the package includes the caliper, one rotor, and the mounting hardware for both. You will have to add brake lever(s) (normally sold as a pair) and brake cables or tubing (depending on if you have mechanical or hydraulic disc brakes).

  15. #15
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    If you have rotors and they have some paint on them,clean it off with a razor blade and a quick swipe of some scotchbrite.No need for new ones.
    Everything should be as simple as possible...But not more so.---Albert Einstein

  16. #16
    Senior Member LesterOfPuppets's Avatar
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    So your bike used to have:

    1 rotor
    1 caliper
    1 brake lever


    Then the caliper went on walkabout? Is that the situation?

    What hubs do you have? You need IS mount?

    I'd just get this setup if it fits your hubs and tabs:

    http://www.chainreactioncycles.com/M...?ModelID=40208
    Last edited by LesterOfPuppets; 08-08-11 at 03:42 PM.
    1980ish Free Spirit Sunbird fixed * 1996 Mongoose IBOC Zero-G * 1997 KHS Comp * 1990-ish Scapin * Olde Western Auto Cruiser.

  17. #17
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    Currently I have:

    2 rotors. (The metal discs that I posted a picture of above).
    Both of them have a small amount of paint on them. A really small amount. About a fingers widths-worth.

    That is all I have in regards to 'brakes'.

    I am missing:

    A brake lever - that you use to squeeze the brakes on.
    A brake cable - that connects the brake lever to the caliper.
    A brake caliper - that actually squeezes the rotor and stops the bike.

    I only want 1 brake. My handlebars are sort of cramped as it is and I am not 'made of money'. It costs 110€ here for a single brake, I don't think I want to pay another 110€ for another one.

    On top of that, it looks moderately difficult to install the brake system in the first place. I know I can get away with being able to do the front brake but the back is a bit trickier. So I think I'll just stick to buying a good front brake and that will be it for me. I just wont go jamming the front brake on when I go flying down a hill.

    If, in the future I need a back brake too I will be happy to buy one and spend the countless hours trying to put it on.

    So now that you know what I currently have. I will tell you what happened to my brake setup.

    I bought this bike from Australia from a mate and had it shipped over to Finland when I moved here. Whilst biking in the forest here my brake just well... it came off. Screws and all. Either the constant bumps, shock, rattling/whatever shook the brake right off it's socket and it just fell off. I only had a back brake at the time. I've had to move places twice since getting here. I ended up getting paid a lot more than I thought I was going to so I moved into a better place after getting employed. Unfortunately, I somehow misplaced, or actually I think my wife did but don't tell her that. The brake lever and cable that I had in a box, as well as a few other things I wont bother mentioning.

    So as crazy as it sounds I have absolutely no components for brakes except for the 2 rotors that are on the bike which apparently have tiny bits of black paint on them. To me it looks like burn marks from hitting the brakes too hard but the front one has them as well. Either because the owner before me used to have front brakes and took them off or because both the front and back rotors somehow got paint on them.

    So now to my problem. I wanted to just by ONE (1) brake for my bike. As at the moment I am a little short on cash. The store I went to quoted me 90€ and then when I took my bike in they re-quoted me 190€:

    59€ - (Mechanical) Brake caliper
    25€ - Single brake lever
    25€ - Brake cable
    26€ - Front Rotor
    26€ - Back Rotor
    40€ - Servicing fee (if they put it all together for me).

    I declined.

    I only wanted:

    59€ - (Mechanical) Brake caliper
    25€ - Single brake lever
    25€ - Brake cable

    So either way the guy insisted that due to a bit of paint on my rotors (front and back) that I needed 2 new ones. (Even though he was only selling me 1 Brake (for the front) because that is all I asked for).

    That took the total back up to basically 155-160€
    + They asked me to wait 4 weeks for them to put it all together. Something that should not take probably more than an hour for an experienced person with the tools... I thought they were barking mad as I looked around and every person working at the store was slacking off entirely, amongst the multitude of bikes. Well surely they don't need my patronage.

    So.. hence I came to the forums here!
    This was to ask, do I really need 2 new rotors? I.E. can I save myself 52€ or so. Because I would really rather not have to pay for something I don't need. If I need a new rotor sure. But I really don't think I need 2, when I am only buying 1 brake setup.

    So at the moment this is my situation.

    I'd like to know however. The rotors I have now, are they the same size as all rotors? I.E. are all (or at least most) brake rotors on mountain bikes/etc. the same size? Will the brake caliper I buy most-likely work with the rotor I already have? I don't mind buying a new one but I would REALLY, REALLY! prefer not to.

    Thanks for listening to my long and boring story.
    Last edited by Kutittaa; 08-15-11 at 02:50 AM.

  18. #18
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    K, makes more sense now. Regarding your current rotors, measure the diameter of the rotor; the most common current mountain bike disc brakes use 160mm diameter rotors, but there are other sizes as well. The brake caliper needs to be mounted to fit the diameter of the rotor.

    Here's what has to match:

    Caliper needs to be compatible with the mount on the front fork. In recent years, things have standardized down to two types, post and tab mounts. If you could post a photo of your fork, we could confirm what type of mount you have (or if it's an older type of mount).

    Lever needs to have pull ratio compatible with V-brakes/mechanical disc rather than the older cantilever brake pull ratio.

    Any new rotor needs to be able to be mounted on your wheel! Current mounting type are 6-bolt and Centerlock, and the wheel hub type determines this. If you could post a photo of your front wheel hub (with current rotor on it is fine), we can see what type of mount you've got.

    Check out the disc brake installation/service sections on the Park Tool website to get an idea of how disc brakes are mounted and adjusted. Assuming all the mounts that you have match current stuff, it's pretty easy to mount the brakes yourself.

    See this for caliper mount types: http://www.bikeman.com/bicycle-repai...4mm-post-mount

    For comparison, a good quality single caliper and disc, with mounting hardware and instructions, cost about $50 at a USA discount mailorder shop:
    http://www.jensonusa.com/store/produ...+Brake+10.aspx
    Last edited by Mondoman; 08-15-11 at 06:01 PM.

  19. #19
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    Hey don't worry guys this can be closed. I bought a brand new bike for 160. It's a Montana MXM. It's an awesome bike. I'm going to sell this bike without the brake on the local sharing page here in my town.

    Thanks for sticking with me thus far.

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