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Gear Sensor failing to detect shifts - gearsensor maintenance

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    Gear Sensor failing to detect shifts - gearsensor maintenance

    Maintenance procedure for sensor failing to detects shifts
    Gear sensor model: GSD5-12V 16.13-00019 but this will likely work with other models as well

    The most likely source of issues is going to be lack of friction between the gear sensor cable and the internal wheel that rotates when the cable moves, or too much friction where the wheel rotates on the spindle caused by mud or debris preventing movement of the wheel.

    Basics of maintenance
    Loosen the shift cable bolt on your derailleur so there is play in the cable.

    Unscrew the 2 silver screws that hold the cover on the shift sensor.

    The cover has a tiny spindle on it, with a wheel attached to it. Theres a groove in that wheel that the cable rides in, and when you shift up or down the wheel moves. Im guessing there is a magnet in that wheel and a hall sensor in the body of the gear sensor that tells it when to cut power. The wheel is on the only exposed component under the cover. If the wheel gets gummed up, or the spindle gets sticky the cable will slide in the wheel groove rather than spin the wheel, and thats the problem.

    All you need to do is pull the wheel off the spindle. Clean the groove on the edge of the wheel out with an old toothbrush, and put a tiny dab of grease into the hole of the wheel where it slides onto the spindle.

    Slide the wheel back on the spindle with the grease and spin it around a few times. It should move pretty freely now. Then just snap the cover and wheel back onto the gear sensor body, making sure the shift cable sits in the wheel groove. Screw the cover back on.

    Tighten up your derailleur cable holding bolt and you're good to go.

    Below is a summary on how a customer cleaned and degreased the cable after using too much grease on the cable, thus preventing the cable from rotating the wheel.

    I took apart the gear sensor and cleaned out dried silicone cement and grease. I cleaned grease off the cable and centered the hub on the gear sensor wheel. Everything is working fine now.

    I also added a section of bicycle tubing to cover and protect the gear sensor from water and mud.
    There was no sign of water and mud in the gear sensor.
    The grease I used (and completely cleaned out of the gearsensor) is fancy low-viscosity white grease I have for plastic-on-metal contact points on ski bindings. Seemed like it would be perfect gear cable grease, especially in Winter! Maybe too perfect for the gearsensor. The last thing was just making sure the hub on the wheel is
    centered. That makes inserting the cable easier.

    I'm the customer with the grease-related Gearsensor detection problems. After I cleaned out the sensor, missed detections crept up on me again. Once again I disassembled the sensor. I solvent-cleaned and lightly sanded the cable at the detector location. I solvent cleaned the pulley wheel. And I lightly greased the wheel hub (magnet). I got best-ever performance after that: 100% detections. Now I believe dried silicone had nothing to do with the problem. Missed detections were all about too-little friction between the pulley and wire.

    My problems began after I installed new Shimano SUS stainless steel cable, SP41 Housing, and greased the cable with Dow Corning Molykote EM-30L Synthetic Polyolefin (PAO) grease. I believe this cable/grease combination is just too slippery for the gear sensor. I greased the pulley shaft with Park Tool Polylube 1000.
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      After this maintenance is done we would recommend protecting the gear sensor as shown in the link below
      Protecting your gear sensor from mud and debris


        Anyone familiar with newer model Shift Sensor model: LL-SS-01? It doesn't have two small screws holding it together. But under the sticker with model number, there is one tiny hole on one side and no scre visible. I'm having same issues of sensor not detecting shifts (90% of time). Was excited to follow your advice above until I saw this. I would pry it apart but first wanted to reach out to this awesome forum!


        • paxtana
          paxtana commented
          Editing a comment
          Hmm.. can you take a pic? Maybe the new version just uses clips for easy assembly. If that's the case you might need a spudger.

        Paxtana , attached are couple of pics (front and back) of Gear Sensor. (What is a 'spudger'?)


          A spudger is a pry tool. Often they are sold as a set so you have a lot of options to pick the best one for a given scenario. It allows you to pry open something without marking it up.

          They look like this.

          Click image for larger version

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          It's a handy tool to have these days as a lot of stuff can be difficult to open. Smartphones, tablets, laptops..they all often require one to service the internals. I have the set pictured above, it cost $10.

          Looks like we might have recently switched to an alternate supplier so I do not have info yet on how to open it up, I'd probably start by checking if that hole has a screw in it and giving that a shot first. But if that doesn't work the spudger's probably the way to go. If it's not screwed in then it's either clipped in with tabs or just glued in. If you can get a pry tool between the two pieces and pry it apart you'd see the clips easily enough and can unclip it. If it's glued you would see that too and might need to pry it a bit harder, slowly working along the edges.