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Mid drive cassettte zip tie mod.

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  • Retrorockit
    commented on 's reply
    I'm guessing that Shimano did each cog separately because the math said each cog would have different force on the chain. Probably a different resistance for each one.

  • Retrorockit
    commented on 's reply
    With this mod the pedals shouldn't be turning.Just the chainring. I haven't had this with the BBSHD. Maybe your front freewheel is sticking.

  • Retrorockit
    commented on 's reply
    I rode it around under power. The square section rubber ring instead of the the zip tie is working just fine. It's back to shifting like an IGH.
    I had tried putting the motor back together before and coulbn't get it to go in, left and did some other things for awhile. I tried putting the rotor in by itself, and that was the problem. It seems the first try I had knocked some grease down into the blind hole the small end of the shaft goes into. It was hydraulic locked and couldn't go in. Once I Q tipped the grease out it went in OK. I put some thermal paste between the stator and housing while it was apart. The new rotor, and old motor with the California Ebike conversion bearing(and shim) seems to be working.
    Last edited by Retrorockit; 07-02-2023, 05:08 AM.

  • Retrorockit
    commented on 's reply
    I haven't ridden it under power yet. I'm finishing up a lot of small changes I made while the motor was broken.

  • Retrorockit
    replied
    I got my assorted O-rings to try. Played around with a few setups, and settled on a 3/16" square profile ring behind the cassette. I felt that it wouldn't take a set and lose tension like a round one might. I greased it with some thick silicone Teflon grease that's used for urethane suspension bushings, it won't wash out, but it's designed to prevent sticking between rubber and metal.. Checked the cassette with a torque wrench. About 1 ft/lb to break loose and peak load when spinning it about 3 ft#. The reason to do testing with the zip ties is the bike returns to normal when they break. But once you have a setup that's working this will avoid the hassle of changing a zip tie every now and then. IDK why Shimano went to all that drama and expense making those complicated freewheel sets.

    Leave a comment:


  • Retrorockit
    commented on 's reply
    I've ordered a pile of parts. I'm probably overthinking this, But I've ordered some 3/16"x 1 3/8 ID rings, and some Square section 3/16x1 1/2 ", and I have some 1 3/4" ID rings to go around the smaller ones. I suspect any of them will probably work just fine. The small ring should sit inside the holes in the back of the cassette and the hub flange and give a smooth surface. The square ring will bridge the holes better if I need more grip.I couldn't really find what I needed locally.
    Be aware that a lot of bikes have a spacer of some kind behind the cassette, so the 3/16" dimension may not always apply.
    Last edited by Retrorockit; 06-20-2023, 05:20 AM.

  • Retrorockit
    commented on 's reply
    "The system had many detractors including Sheldon Brown. Most thought it was unnecessarily complex and heavy. I do think it is heavier than a standard freewheel however, it is also quite handy especially if you are an urban commuter who has to do a lot of start and stop biking. By not having to pedal in order to shift, you can shift into and easier gear while you are coasting to a stop so that you’ll be in the appropriate gear when you’re starting off again. You can also shift into a gear while you’re at a stop and as soon as the rear wheel starts moving the chain will fall into the gear that you’ve preselected."
    IDK how to respond to this. Do I have to weigh my zip ties and O rings?
    Last edited by Retrorockit; 06-19-2023, 05:40 AM.

  • Retrorockit
    commented on 's reply
    All you need is zip ties, or thick rubber bands to do the same thing. LOL

  • ncmired
    commented on 's reply
    I found this quote, "each ring has its own set of pawls, so take my advice and don’t open one of these".


  • Retrorockit
    commented on 's reply
    I've only seen the video. But Shimano dragged each cog separately. It was freewheel tech. But the whole cassette approach works just as well.
    Someone with a dork ring suggested the friction method. My XT hubs have a high flange so I can run 1 or 2 O rings to try it.
    Since it basically only moves if the chain gets jammed up somehow it doesn't have to be high tech. It's just to make the chain move around the chainring when coasting. Under power it does absolutely nothing.
    Last edited by Retrorockit; 06-17-2023, 05:30 AM.

  • ncmired
    replied
    On the Shimano FFS freewheel, is that what they did? Ever taken one apart?

    I've never seen one.
    Last edited by ncmired; 06-17-2023, 05:22 AM.

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  • Retrorockit
    replied
    I'm going to move away from the zip ties. I think they're the right way to do R&D on this. But when you get to the point they don't break any more there is another way to do this.
    I'm going to put 1 or 2 (concentric for 2) 3/16" O rings behind the cassette. I'll put some silicone grease on them so they don't get stuck and they will provide a friction type clutch instead of a breakaway solution. It will mostly be stationary since I'm no longer breaking zip ties. This may allow me to run the chain at normal length. Instead of breaking a zip tie it will just slip as needed.
    This is what I've found actually riding this setup.
    When leaned over in turns and can't pedal you can upshift and downshift as desired. ( I've spit the chain form shifting w/o pedaling like this)
    When accelerating in the higher power settings any shift when pedaling will be a power shift and can bend/break parts. Now you can pause pedaling to shift w/o damage at high power levels.
    Pedaling while braking is stupid. With this mod you can dump multiple gears while slowing down in real time w/o pedaling. This does require a manual gripshifter, not some single shot trigger shifter.

    Leave a comment:


  • Retrorockit
    commented on 's reply
    I waited to post here until I knew it had nothing to do with it. But the chain management battle of the parts continues. 1 for the BBSHD, and one for the T-Cycle battery bracket. The zip tie is surviving all of this mechanical mayhem.
    I think the shaft is probably bigger all the way through, not just at the bearing, (It would be hard to press the rotors laminations on an 8mm shaft with 2 larger ends on it) and getting the keyway away form the change in section, plus a free area to absorb some torque will make big difference. If the shaft is full 9mm that's 26% more cross section right there. Keeping 2 stress risers away from each other is a big plus. TSDZ2 has shit like that and they never fix it. At least Bafang did something about it.
    Last edited by Retrorockit; 03-12-2023, 02:57 PM.

  • Retrorockit
    replied
    No news isn't always good news. To sum it up the BBSHD broke the first 15t idler bracket. So I added the massive battery hanger clamp and the 1 1/4x3/8" 6061 bracket. Passed all tests including wheels up launches. The during fairly light loading the BBSHD quit providing power. It turns out mine is the older version and the motor shaft snapped where the gear meets the rotor. This is uncommon but not unheard of. So the winner is the failsafe breakaway zip tie! It didn't break! Of course I wish that was the problem.

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  • Retrorockit
    commented on 's reply
    All the torque was pivoting around one M6 bolt. The tab to the other bolt was too thinned out for this purpose. It was good for proof of concept, and mock up duty. 2x M6 bolts seems like enough but they both need to be sharing the load.
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