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Thread: Disc brakes

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    Disc brakes

    I don't know about you guys but here in Montreal morning are getting chillier. I'm slowly starting to think about my winter bike. I want aluminum frame to avoid rust. I want try something new to me. Something call Disk (or Disc) brake. I never really work with disc brake. Is Disc brake bosses (the part of the frame or the fork where you attach the mechanism) are all the same for any disk brake. Or different attachment for different mechanism? DO you have good online ressources to know more about disk brake. I also want to use gear hub, something like the 8 speeds SA offers X-RK8(W) maybe the "what's about internal gear and subzero weather" question will be part of another post.

    David P P

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    coprolite fietsbob's Avatar
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    The frame will need to have the Mounts on it , and the fork to have another set.
    they would both be on the left side ..

    there are a few different IGH with disc mounts
    Sturmey's 8 speed you need a pretty small chain ring up front ,
    because other than Low the gears are all overdrive .
    so with bigger wheels the ratios get huge and useless pretty soon.

    A 5 speed OTOH has 2 reduction gears and 2 overdrive gears.

    for a frame without the disc mounts , consider Sturmey's Drum Brake Hubs.

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    Sir Fallalot wroomwroomoops's Avatar
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    Quote Originally Posted by DAVIDPP View Post
    I want aluminum frame to avoid rust.
    Stopped reading right there. All my bikes have steel frames, the average age is 15 years and two of the bikes are ~30 years old. None has any serious damage from rust (the little there was, it was easy to paint over with Hammerite). And I live in ****ing Finland!

    And did you know that unprotected aluminum frames also corrode when exposed to the elements? The thin layer of native oxide on the surface of aluminum is rapidly hydrated in rainy weather or humid air. New native oxide will be formed, but it well be promptly removed by a process of hydration, as long as there is presence of water. The reason people are unaware of it, is that the the oxide and the hydroxides of aluminum aren't brown or orange.


    Going with an aluminum frame "to avoid rust" is dumb.

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    coprolite fietsbob's Avatar
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    If you use the term 'Corrosion' (instead of 'rust') it applies to both steel and aluminum.

    road salt will effect both.. wash down the bike with fresh water, often.

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    Keep reading. My question was more about disc brake mount. Is there one standard. (We talk about bike component ,since when there's ONE single standard) I want to know what are the standards and what should I look for when I shopping around for a frame and fork to use disc brake.

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    Sir Fallalot wroomwroomoops's Avatar
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    Quote Originally Posted by DAVIDPP View Post
    Keep reading. My question was more about disc brake mount. Is there one standard. (We talk about bike component ,since when there's ONE single standard) I want to know what are the standards and what should I look for when I shopping around for a frame and fork to use disc brake.
    Pretty much every bike frame and fork that is disc-brake compatible has "51 mm International Standard" also known as simply "IS mounts".

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    coprolite fietsbob's Avatar
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    there are 'Post mount' on some MTB forks but all calipers can fit either sort.

    why not drop by a Bike shop and look around a little?

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    I'm sorry about question that might llok stupid but I'm a newbee with disk brake

    Look like The rotor is often 160mm Is the size of the rotor is important? is calipers are design for different rotor sizes or caliper can be adjust to the rotor size?
    What'S about the lever. Do you have lever specific for disc brake. I know there is mechanical and hydrolic disk brake. I suppose the lever will be made for one or the other right. Will hydrolic work ok in winter?

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    coprolite fietsbob's Avatar
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    no .. there are a different set of adapters in between the fork and the brake caliper
    a bigger disc uses a adapter.. to set it in the right place .

    It's easier to see if you go into a bike shop and look at how the bikes are set up.

    for the discs they come in 140 160, 180 and 210.

    for street riding 2 160's will be fine . harder riding off road ,
    and decending at high speeds then the discs that are bigger are chosen.

    Hydraulic disc brakes are going to cost you more ..

    since there is a seal around the piston to hold the oil in ,
    there is little possibility of contaminating the oil,
    with road grit and such.
    Last edited by fietsbob; 09-12-12 at 02:03 PM.

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    Quote Originally Posted by wroomwroomoops View Post
    Pretty much every bike frame and fork that is disc-brake compatible has "51 mm International Standard" also known as simply "IS mounts".
    Sort of, the IS mount is now just about obsolete for forks, with the post mount now the standard fitting; for the frame, post mounts are becoming more common, too early to tell if this will supersede the rear IS mount as well.

    Disc brakes haven't been available for several years with IS mounts, all are now sold as Post Mounts, with IS adaptors.

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    Sir Fallalot wroomwroomoops's Avatar
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    Quote Originally Posted by DAVIDPP View Post
    What'S about the lever. Do you have lever specific for disc brake. I know there is mechanical and hydrolic disk brake. I suppose the lever will be made for one or the other right. Will hydrolic work ok in winter?
    Yes, mechanical disc brake calipers are cable-activated, while hydraulic calipers are activated by a fluid in a flexible pipe and requires a suitable hydraulic lever. (actually, "mechanical" is a misnomer, as both are, essentially, mechanical).

    Hydraulic brakes will work fine in winter, as the liquid used is some kind of long-chain oil, usually of mineral origin. However, I have not seen a real advantage of hydraulic vs. mechanical disc brakes. Perhaps there is, if you are into extreme sports? I don't know.

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    Sir Fallalot wroomwroomoops's Avatar
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    Quote Originally Posted by jimc101 View Post
    Sort of, the IS mount is now just about obsolete for forks, with the post mount now the standard fitting; for the frame, post mounts are becoming more common, too early to tell if this will supersede the rear IS mount as well.
    Is that so? Post mounts are so rare where I live, that I have never seen a fork with one, In Real Life. I know they exist, I know what they are, I have seen pictures. But never IRL.

    EDIT: to be completely explicit, I have never seen in real life a fork like this:



    Quote Originally Posted by jimc101 View Post
    Disc brakes haven't been available for several years with IS mounts, all are now sold as Post Mounts, with IS adaptors.
    That's true.
    Last edited by wroomwroomoops; 09-12-12 at 02:12 PM.

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    coprolite fietsbob's Avatar
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    Yea IS tab Bikes are shipped with the right adapter to mount the caliper , as they build it up.

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    Quote Originally Posted by wroomwroomoops View Post
    Is that so? Post mounts are so rare where I live, that I have never seen a fork with one, In Real Life. I know they exist, I know what they are, I have seen pictures. But never IRL.
    Given that Rock Shox, Manitou, Magura, DT Swiss, Marzocchi, are Post Mount only now, and have been for several years, not sure what forks you are looking at.

    If you look at the Suntour range, their MTB forks are all Post Mount, you have to look at the treking / non-MTB ranges to find IS mounts now. Road discs fork manufactures don't seem to have made up their mind yet, ENVE & Colnalgo use Post Mount, others are using IS

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    coprolite fietsbob's Avatar
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    non suspension forks are more likely IS, because the tabs are a more common braze on.

    IE rigid Forks..

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    Sir Fallalot wroomwroomoops's Avatar
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    Well, I'll keep my eyes out for post mounts on forks. I want to touch one.

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    Quote Originally Posted by DAVIDPP View Post
    Look like The rotor is often 160mm Is the size of the rotor is important? is calipers are design for different rotor sizes or caliper can be adjust to the rotor size?
    On the design/theoretical side, larger rotors will exert more reactive-torque for any given clamping-pressure from the pads (generates more deceleration). In the practical usage end, you run into manufacturing, cost, weight and maintenance questions as well. So there's a balance of sorts. The leverage-ratio of the lever-to-caliper typically incorporates a certain rotor size in mind. And the curvature of the pads are designed for a certain rotor size as well. In the end, as long as the components match and fit, that's all you'll want to be concerned with.

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    So Montreal, i think avid bb7 mechanical disc brakes with full housing would fit the bill, that's what works for me in the Boston MA area.

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    You guys still havent addressed mounting the disk to a wheel. Rim brake wheels typically dont have hubs that can mount disks. DO I understand there is more than one style of disk mounting?

    -SP

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    Disc Hubs and Rotor types.

    Rohloff uses a 4 bolt disc: http://www.rohloff.de/en/products/sp...scs/index.html

    6 bolt rotors can be used on centrelock hubs with an adapter but centrelock rotors can't be used on 6 bolt hubs.

    Shimano-Centerlock-To-6-Bolt-Adapter

    Probably also worth mentioning that there are two types of mechanical disc brake calipers, Road specific and Mountain specific. The two types have different pull ratios for use with certain levers.

    Road versions work with drop bar levers and cantilever type levers.
    Mountain versions work with v-brake levers or linear brake levers.
    Last edited by cobba; 09-14-12 at 12:34 AM.

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    Here some pic for you. I'm ok about Disk brake caliper mount standard for frame and fork. I beleive my frame have the 51mm International standard. But the mount doesn't look like any other mount saw when I googled it. What you guys thinks.

    I freecycle a set of disc hub at my bike coop. The front already have a disc 180mm attach with 6 torx bolt says Fuji on the hub. The rear is Quando, no disc for that one but a cassette 8speed that look new. (not in the picture).

    With the bike coop I have the choice between 7 disc brake caliper.

    TEktro IO, Lyra or Aquila. Says Lyra and Quila are "Ball bearing cable actuated mechanical disc brake" ??? what exactly is that?
    other choice are Shimano BR_M416 front or rear and Shimano BR-M495

    They are all mechanical and takes 160 rotor. I beleive they all take V-Brake lever.

    Thank for you advise everyone.photo 1.jpgphoto 2.jpgphoto 3.jpgphoto 4.jpg

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    coprolite fietsbob's Avatar
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    Going to a parts expanded diagram for like Avid, which I have downloaded a PDF,
    there is a ring shaped ramp
    that is rotated by the arm with the cable attached to it, it increases the pressure
    exerted on the Movable pad, pressing it against the disc..
    to facilitate rotation between the stationary pad pressure plate and pressure transfer ,
    from the ramp ring , which rotates, there are a few bearing balls in the mechanism.

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    Quote Originally Posted by DAVIDPP View Post
    I beleive they all take V-Brake lever.
    The Tektro Lyra is a road disc brake, cross it off the list if you're going to use v-brake levers.

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    Sir Fallalot wroomwroomoops's Avatar
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    Quote Originally Posted by DAVIDPP View Post
    Here some pic for you. I'm ok about Disk brake caliper mount standard for frame and fork. I beleive my frame have the 51mm International standard. But the mount doesn't look like any other mount saw when I googled it. What you guys thinks.

    I freecycle a set of disc hub at my bike coop. The front already have a disc 180mm attach with 6 torx bolt says Fuji on the hub. The rear is Quando, no disc for that one but a cassette 8speed that look new. (not in the picture).

    With the bike coop I have the choice between 7 disc brake caliper.

    TEktro IO, Lyra or Aquila. Says Lyra and Quila are "Ball bearing cable actuated mechanical disc brake" ??? what exactly is that?
    other choice are Shimano BR_M416 front or rear and Shimano BR-M495

    They are all mechanical and takes 160 rotor. I beleive they all take V-Brake lever.

    Thank for you advise everyone.photo 1.jpgphoto 2.jpgphoto 3.jpgphoto 4.jpg
    Yes, IS mounts, both frame and fork.

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