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BBS02 mid-drive kit BASIC issues - FIXED on Rockhopper!...

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    BBS02 mid-drive kit BASIC issues - FIXED on Rockhopper!...

    First off, I love this kit. Purchased over a year ago and have put nearly a thousand mile on it (I live in NE Ohio, so no small achievement weatherwise lol). So, kudos to LunaCycle for developing a pretty legit kit right from the getgo.

    However, as with most one-size-fits-all "kits", specific adaptation to each bike can be challenging and can make the difference between a good installation experience, and a bad one. In my case I installed the BBS02 on a 29" Specialized Rockhopper with the intention of using it for mostly road commuting and occasional MTB useage.

    During the install I immediately recognized one of three serious shortcomings - securement of the motor using the large nut on the lower bracket is a recipe for disappointment. With even mild off-road use the likelihood of those nuts getting loose is nearly 100%. The first mod was creating the large white triangular bracket that attaches to the motor case, the lower bracket, and a two-piece clamp. Solid. 100% not going anywhere.

    After finally getting some time on the new setup it wasn't long before I realized that chain drop (chain popping off during bumps) is a huge and extremely annoying problem. This issue stems from the fact that the front derailleur is removed and therefore there is no longer any lateral containment of the chain. Any side to side jostling of the chain and zing the chain falls off. The solution came in the form of 3D printing a guide and mount that conveniently attaches the 2-piece clamp described above. Previously I'd averaged 1-2 drops per ride, and with the guide in place I got NONE ever since even with intentional attempts to drop it going over rough terrain.

    The last bit is a battery support. Although the failure mode never actually revealed itself, my anticipation was that the two little water bottle screws holding that big ass battery weren't going to last long given how much the battery wobbles on that skinny attachment plate. In this case the solution was an aluminum bracket that holds the rearmost part of the battery and holds it firmly in place. The design is trickier than it seems because its size is optimized for support and rigidity, but still allows for battery removal (it's tight in there!).

    All these parts have been designed in Solidworks (3D design program). With enough interest I could be talked into making more of these in quantity. The challenge is redesigning them to be flexible enough to fit the majority of bikes.

    Geo.


    #2
    With even mild off-road use the likelihood of those nuts getting loose is nearly 100%.
    6000mi of hard pounding on a BBSHD build and the nut has never come loose - blue loctite (not even red)

    After finally getting some time on the new setup it wasn't long before I realized that chain drop (chain popping off during bumps) is a huge and extremely annoying problem.
    Had this issue with regular chain rings on my mid but once I got settled in with a narrow-wide have never had a chain drop in >3000mi

    I have another bike (hub) that has a much worse chain line and it would drop almost every other ride - the narrow-wide helped but I still had a lot of drops... I fabricated something similar to what you did and that helped a ton but if the chain did get dropped it was far more a pain to put it back on with the guide in the way... eventually ended up putting guards on both sides of the ring and after a fair bit of fussing now have a solution that has yet to drop the chain and doesn't interfere with maintenance - has the added benefit of not sucking trouser legs into it too

    Although the failure mode never actually revealed itself, my anticipation was that the two little water bottle screws holding that big ass battery weren't going to last long given how much the battery wobbles on that skinny attachment plate.
    Conventional wisdom is to simply use a couple of straps around the battery and frame... I was lazy about this for a while and a couple of the tabs broke on the battery mount and the battery case cracked but I've never had any issues with the threaded portions in the frame and I haven't heard that as any kind of frequent complaint (not even sure if I've ever heard of it)

    YMMV

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      #3
      Nice job on solving those issues. I like your motor mount addition way more than I like loctite. And the 3D printed guide looks great! Maybe add some stylish lightening holes to your battery support?

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