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Tandem ebike conversions using BBSHD or BBS02

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    Tandem ebike conversions using BBSHD or BBS02

    This thread is an assortment of pics and notes from builders that have done this before. Info may be incomplete, incorrect or model-specific, but generally it is possible to do a tandem install with these motors.

    BBS02 build. The HD won't fit in this tandem - too wide and interferes with stoker's timing chainring.

    An easy & painless process of building an electric bike.

    I installed a BBSHD on our Calfee Carbon Fiber tandem. The tech from Calfee walked me through the process. I installed the motor in the stoker position and went with RH drive for the front to rear chain. A pair of fixie cranks from eBay solved the drive crank issue.

    You may have to get a new front eccentric so that you can use conventional cranks.
    Q&A on the above build
    Q: How exactly are you connecting second chain ring to the spare axle?
    A:The second chain ring is attached to the square drive fixie crankset and attaches directly to the Bafang spindle.

    Q: How are the arms and external ring moving independently from the Eclipse?
    A: The eclipse is bolted to the Bafang motor and the fixie crank attaches to the Bafang shaft. It replaces a single crankarm.

    Q: Did you encounter any difficulties in alignment when swapping this over to belt drive?
    A: I had to get a special long square drive front spindle from Phil Wood. A LBS ordered it for me. The Q factor is wide but it is not an issue.

    This install was performed on a Hokitika Hoka Tandem. I had absolutely no problems with the install, just three hiccups. The first was that I needed a BB spacer to give clearance on the right side chain stay. Due to hiccup number one, I had hiccup number two which was the stabilizer now required a bit MORE spacers and longer bolts to attach to the left side under the BB lockdown nut. (pretty sure those are not correct names for the items, but you probably know what I am talking about. I am posting pictures of this. Hiccup number three came as a complete wake up moment as I did not know, and I have been riding tandems for 10 years, and regular bikes for 30+, and I never knew that crank arms had the square taper mounting holes oriented two different ways! I just do not know the reasoning behind this, but if you were to hold a crank arm where the BB spindle mount is on top, you will see either a square or a diamond hole. The kit comes with diamond holes arms. I had to use the left side crank from the tandem due to the timing chain and it had a square hole, so when installed, it was not clocked right. To correct this temporarily, I just mounted the left side as normal, right side I used the triple crank to keep the clocking correct until the new crank arm comes in. It is ugly, but worked beautifully. My goal in all of this is to be able to quickly revert this back to a non-e-bike. I was even going to leave the front derailleur hooked up but the wide range of the cassette caused noise, so I just removed the derailleur but kept the cable tied up and in place.

    BBSHD used for this conversion. No additional info available

    I'm in the middle of converting a Gary Fisher Gemini tandem bike to a BBS02 mid drive.

    Not easy. The BB axle, eccentric, and shell are not standard. It took some machine work to make spacers so the 100mm BBS02 would fit.


      The Gary Fisher is up and running. It has some unique features such as a 7 speed Nexus internal hub, two slightly different sized ring gears for the stoker and captain, and the "synchro" chain has been moved to the right side. Different rings are a matter of what was on hand, not by design.

      Synchro is in quotes because the riders aren't going to be synchronized b/c of all the freewheel action, front and rear. The different sized rings also contribute, but that's inconsequential.

      I have a friend who has a production electric tandem, and it is set up the same way and essentially works alike except for the internal hub. Interestingly, on my tandem and his production bike, the stoker can be the only power source (w/o assist) if the captain gets lazy and stops pedaling!

      This was a fun project that I took on because the derailleur hanger was damaged in an accident. It took a bunch of hoop-jumping to make this nice vintage cruiser. I couldn't stand to junk this frame, so.....


        I want to convert a Co-Motion Speedster Tandem to an etandem. My concerns are clearance between motor and timing gear as I am running a Gates belt.
        I also have DaVinci square drive cranks with the converted spiders for the Gates belt sprockets.
        Has anybody been down this road?