Disabling Nexus 7 Coaster Brake

Discussion in 'Cycling Equipment' started by Dan Burkhart, May 15, 2006.

  1. Dan Burkhart

    Dan Burkhart New Member

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    Is this something that can be done without totally dismantling the hub? I have a line of bikes that is only available with the coaster brake version, and this feature is costing sales. The bikes are equipped with front V brakes and posts for rear brakes, so retro-fitting is not a problem.(Except that the frame is deeply swooped for easy boarding and would probably require an extra long cable.) I plan to contact Shimano directly on this, but I anticipate a " what the heck do you want to do that for?" response, so I thought I'd try here first.
    I've suggested to the OEM they should switch, but they are disinclined to do so.
    Thanks
    Dan
     
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  2. landotter

    landotter Guest

    Dan Burkhart wrote:
    > Is this something that can be done without totally dismantling the hub?


    Nope.

    If it was a roller brake, yeah, just remove it.

    I'm trying to remember if removing the brass brake pad from a coaster
    disables it or is a really really bad idea--and the mechanism in the
    Shimano is likely to be a lot less forgiving than messing with an old
    single speed Torpedo coaster.
     
  3. Dan Burkhart

    Dan Burkhart New Member

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    OK, I got this straight from Shimano.The brake shoes lift right out the left side after removing the brake arm and cover. They said it does not adversely affect the operation of the hub.
    I just tried it. Five minute job.
    Dan
     
  4. Chalo

    Chalo Guest

    Dan Burkhart wrote:
    >
    > I have a line of bikes that is only available with the coaster brake
    > version, and this feature is costing sales.


    What kind of lame, joyless customers are those? Coaster brakes are
    fun!

    Chalo
     
  5. Dan Burkhart

    Dan Burkhart New Member

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    The bike these are in are designed for people with mobility problems that inhibit the ability to lift the leg high enough to mount a conventional bike. The ability to rotate the crank backwards to a comfortable starting/ mounting position is of significant value to these folks. I don't think they are much interested in doing rear wheel skid outs.
    (Yeah, I know you were just joking.)
    Dan
     
  6. Chalo

    Chalo Guest

    Dan Burkhart wrote:
    >
    > Chalo Wrote:
    > >
    > > Dan Burkhart wrote:
    > > >
    > > > I have a line of bikes that is only available with the coaster brake
    > > > version, and this feature is costing sales.

    > >
    > > What kind of lame, joyless customers are those? Coaster brakes are
    > > fun!

    >
    > The bike these are in are designed for people with mobility problems
    > that inhibit the ability to lift the leg high enough to mount a
    > conventional bike. The ability to rotate the crank backwards to a
    > comfortable starting/ mounting position is of significant value to
    > these folks. I don't think they are much interested in doing rear wheel
    > skid outs.
    > (Yeah, I know you were just joking.)


    So maybe "lame" was not the right word to use in jest....

    That does seem like a questionable feature to put on such a bike,
    unless they also anticipated that the user's hand strength might be an
    issue.

    Chalo
     
  7. dbonner

    dbonner New Member

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    hello, do you know if this still applies to the 2013 sg-7c nexus 7 speed with coaster brake? also, does the mod just remove the braking effect or does it allow fraa backpedaling as if the hub had never had a coaster brake installed? my bike is an almost new staiger sinus that has full hydraulic front and rear brakes so dont ask me why they fitted a coaster brake hub. it makes no sense at all. thanks in advance, david
     
  8. alfeng

    alfeng Well-Known Member

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    BECAUSE any-and-every coaster brake requires the ARM which is anchored to the non-driveside stay on the left side of the hub for the brake to function, REMOVING (!!!) the arm will effectively disable the coaster brake.
     
  9. dbonner

    dbonner New Member

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    Hi, are you sure? The shimano is a fully integrated 7 spees hub with coaster brake. Are you sure that just letting the coaster arm spin with the Wheel will not also affect the planetary gearset? I know that sun and planet gears can require a fixed non rotating reference to function (at least in car gearboxes) thanks david
     
  10. dabac

    dabac Well-Known Member

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    The arm is unlikely to clear the stays well enough to rotate, so any success is dependent on removing the arm as opposed to merely unhooking it.
     
  11. dbonner

    dbonner New Member

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    Hi dabac, thanks but i already did plan to do as you say and remove the arm. The issue i have is with the gearbox. Can anyone tell me if there is any link between the coaster brake and the gearbox in the design ie does the planetary gearbox by any chance use the coaster brake lever as part of its gearbox design in which case removing the lever might prevent the gearbox from operating. I dont know how the shimano is arranged internally but if you take a typical sun and planet geartrain, it requires a fixed non rotating attachment to be able to transmit power (except when in straight through direct drive) . Is this attach point only on the sprocket side, in which case im fine, or is it also on the brake side shared w the brake? Can anyone tell me? Thanks
     
  12. alfeng

    alfeng Well-Known Member

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    FWIW. Typically, the AXLE on an internally geared hub has FLATS which will preclude rotation when the hub is in the frame's dropouts ...

    That is, the axle's actual diameter is larger than on a "normal" rear hub & the axle has parallel FLAT surfaces which allow the hub to nest in the dropouts & not rotate .
     
  13. dabac

    dabac Well-Known Member

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    Possible I suppose, but I haven't seen that. IME, anti-rotation washers, engaging the axle flats, and then extending a tab into the dropout slot, seems more common.
     
  14. alfeng

    alfeng Well-Known Member

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    HMMmm ...

    Well, YOU may certainly be correct ...

    Unfortunately, it doesn't really matter TO ME, either way ...

    IMO, it's just not that complicated to see what configuration will-or-will-not work ...

    Simply put ...

    • IF 'I' had a question about whether or not simply removing the "arm" + relying on the "flats" for the planetary gear mechanism to function properly, then 'I' would simply put the rear wheel into a truing stand OR in a makeshift, DIY support to see if I could effectively shift the internal gears when the axle is stablized in the frame's "dropouts" ...

    • If it won't shift when in a truing stand OR DIY stand, then the OP needs to buy a new hub because as many NEXUS hubs do NOT have a coaster brake as may have them.

     
  15. Cucurutxo

    Cucurutxo New Member

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    Hi all,

    Since I have been unable to get myself a replcement brake shoe for my nexus 7 I have decided to convert it into a freewheel. I guess it will be useful for many people who can't find spares.
    By removing the brake shoe, you disable the coaster brake, but you are not able yet to backpedal.

    You may need to follow the service manual until step 10 is completed (they all work the same way, nevermind if it is not a C26 as in the link attached I did it on a C21).

    http://avantum.info/downloads/Shimano_Nexus_Inter-7_coaster_brake.pdf

    Don't panic, is way easier than it seems!!!

    When that is done, just remove the retaining ring and the two dropouts it holds as shown on the pictures. They are the ones that do not allow backpedal.

    Take into account you can backpedal as in a freewheel but the planetary gear system is runing backwards too so backpedaling is noisier and has more friction than in a regular freewheel. Works correctly anyway.

    By tha way, if anyone knows where to find a brake shoe for a SG-7Cxx, please advice.



    [​IMG]

    [​IMG]

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  16. adoler

    adoler New Member

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    Hello to everybody

    I disabled the coaster brake of my Nexus sg-c3000-7c according to Cucurutxo's instructions. First of all, I have to mention that it is not an easy thing for an unexperienced guy. But It worked at the end, I just removed the ring and the two dropouts as Cucurutxo showed in the photos, I left the brake shoes inside the hub. Coaster brake is not working now and I can back pedal easily. However the hub is not freewheeling now, the pedals spin with the rear wheel unless my feet are on the pedals. I appreciate any help about this issue.
     
  17. adoler

    adoler New Member

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    reply to my question above: I understood that the pedal spin with the rear hub was due to the dust between the sprocket and the gear hub, I used WD40 and the problem was solved. Now the hub is working properly without the coaster brake.
     
  18. Ade3d

    Ade3d New Member

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    Hi, i
    Just made an account for this. I disassembled the axle but i'm really not sure what i need to remove. The breakpads (?) are an obvious, but could you specify what you meant with bearing and the 2 dropouts?

    Thanks
     
  19. Ade3d

    Ade3d New Member

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    If i'm correct i should remove parts 4 and 5?
     
  20. Carlos Olivares

    Carlos Olivares New Member

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    Hi, I'm trying to do it, can you put the images again, please
     
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