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Slipped snap ring on my nexus 3

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    Slipped snap ring on my nexus 3

    Looking for some suggestions. I'm in the process of coming up with a belt drive system on my bike. I have been testing out a 10MM offset back sprocket that I would then use to attach the CDX belt cog to.
    Here is the problem the snap ring continues to let loose when under load. Sometimes starting out and sometimes going fast. I make sure the snap ring is seated tight. I have removed the snap ring a reattached probably 4 times.


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    #2
    The 10mm offset is probably putting a huge side load there that a flatter cog wouldn't have. IDK about the belt drive, but getting a flatter cog that can run the thinner 7/ 8speed chain might solve the immediate problem. Multispeed chains are designed to run at an an offset. Single speed chains need to run straight.

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      #3
      I was wondering about that with the offset cogs. I ended up going back to a 10 speed so never got one of the offset ones.

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        #4
        With the 1/8 cogs on Shimano hubs usually meant for 3/32 cogs, you'll need to remove any stamping burs from the cog's mounting surfaces (both sides), and fully seat the clip with a punch. Since the cog has so much offset and side loading, you may also need some clip trapping screws.

        People own and use this offset cog, and there seems to be multiple manufacturers for it - so I guess it can be made to work. I personally haven't tried it.

        DIY Gates belt drives can be very costly, with the trial and error incurred.
        BBSHD / BBS02 IGH Builds: Nexus / Alfine 8: 1 2 3 4 5 6, Rohloff: 1

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          #5
          I would imagine the offset cogs are fine with human power but I wounder if our mid drives are maybe pushing them a little too hard?

          What's a clip trapping screw?

          Comment


          • ncmired
            ncmired commented
            Editing a comment
            Clip trapping screws is a (probably hoaky) thought I had while lying here in a hospital bed. I like Retro's idea of radial screws, but with the sprocket's dish curvature that may be hard to pull off. Instead I was picturing drilling and tapping three M3 screw holes inside the cup, on the flat area, at a far enough radius so that the screw head (picturing a 3mm metric head screw) just clears the snap ring when it's fully seated in the hub groove.

            Meanwhile back to the pain killer and little sleep.
            Last edited by ncmired; 2 weeks ago.

          • Retrorockit
            Retrorockit commented
            Editing a comment
            I think a center punch would allow a small hole to be drilled, and with a long enough bit just cross drill it for 2 holes at once.A machinist center hole drill would be nice.
            https://imgs.search.brave.com/Nvzhk2...y1sMTAwMC5qcGc

            Hopefully only the teeth are heat treated. I am assuming a drill press would be involved.
            Last edited by Retrorockit; 2 weeks ago.

          • Retrorockit
            Retrorockit commented
            Editing a comment
            "Meanwhile back to the pain killer and little sleep."

            I hope you get out of the hospital soon.The less time spent there the better.

          #6
          Got the offset sprocket to work!
          Sourced the heavy duty 1-1/4 snapring (perfect thickness) from McMaster-Carr​ and gave it a 20mile test ride. Applied approx 1000watt starting from a standstill, uphill, throttle only without issue.

          ncmired​ hope you are well.

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            #7
            Well done on the find, and thanks - I've been released from the hospital's grip.

            BTW, was the Shimano snap ring square edged? I thought they all were, but coinky dinky I was working on a Nexus 3-speed today, and it had a round edge one not unlike the Sturmey Archer ones. Tossed in favor of a square edge one ...
            Last edited by ncmired; 1 week ago.
            BBSHD / BBS02 IGH Builds: Nexus / Alfine 8: 1 2 3 4 5 6, Rohloff: 1

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