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GT Ricochet with BBS02

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    GT Ricochet with BBS02

    Luna was offering a deal on a BBS02 kit which included the motor, battery, and all associated components. My original plan was to install the kit on my primary mountain bike (Ghost Kato X). When the kit arrived, I realized the that bottom bracket shell was WAY too wide for BBS02. Even a little bit of research would have told me that this kit wouldn't fit my bike (the specs are all over the forum and website). I decided to find a different bike and landed on a cheap ($350) GT Ricochet. The bottom bracket shell on the Ricochet was near 73 mm, but I figured I could make it work.

    I have virtually no experience working on bikes so I spent a lot of time on youtube learning about bottom brackets, cranks, etc. I bought three tools for this job: crank puller, bottom bracket remover, and a spanner wrench. While you could probably get away without the crank puller and spanner wrench, I don't recommend it. I had to pull the cranks off several times to make adjustments and it would've been a pain without these tools.

    After removing the cranks and bottom bracket and sliding the motor in, it was clear that I had problems. In short, the geometry of the Ricochet is a challenge for the BBS02. The combination of a wide BB shell and frame dimensions designed to accommodate fairly fat tires made this install more of a challenge than I was expecting. I suspect that the BBSHD is probably a better fit for this bike, but I didn't want to return it , so I proceeded with the install. With the BBS02 fully inserted into the shell (no spacers), I found that the chainstay was interfering with 48T chain ring. It wasn't even close, and because I barely had enough room to fit the steel nut on the other side, I couldn't add enough spacers to fix the interference. I decided to flip the chain ring so that it offsets outward instead of inward, which is probably not recommended but it seemed to the only conceivable way to make this work. Even with the chain ring flipped, I discovered that I still had issues because the motor drive housing was resting (and digging into) the frame. I had no choice but to add a 4 mm bushing to add relief. This meant that I had even less room to work with on the other side (to fasten the steel nut on), but it was necessary.

    Now that I had everything working on the drive side, I proceed on the non-drive side. I discovered that there was a large gap between the triangle mounting plate and the motor and after researching on the forum I quickly discovered that this is a common issue in 73 mm bottom bracket bikes. Someone on the forum recommended replacing the short M6 bolts with 20mm bolts and enough washers to fill in the space (5 in my case). That's exactly what I did and it seemed to work well. Now it was time that I fasted everything together with the steel BB nut, and since there was no chance of me fitting the secondary aluminum nut, I decided to Locktite it and tighten it as much as possible. Installing the battery, brakes, throttle, display, and sensor was a breeze and the color coded sockets were very easy to figure out.

    I wasn't sure how the bike would ride with the chain ring flipped, and I halfway expected to immediately break my chain. Thankfully, this didn't happen and the bike rides better than I anticipated. The motor puts out so much power and it's the quietest ebike I've ever ridden, which is important to me. Fit issues aside, I don't think there's any question about the quality of these components and I'm very happy with the build. I'm probably going to replace the 48t chainring with a smaller ring with less of an offset to see if I can improve the chainline. If I don't do something I think a chain break is in my future. Anyone looking to have an easy install should probably not install THIS motor on THIS bike, but it can be done. It was a fun project and I already want to build another one.
    Long nuts with extra washers to fit the triangle plate to the motor Motor drive housing touching frame Not an ideal chainline This thing rips!
    Last edited by jsullivan; 02-18-2018, 10:25 AM.
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