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BBSHD on a Salsa Bucksaw - Yeehaw!

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    BBSHD on a Salsa Bucksaw - Yeehaw!

    This is a build I have been dreaming about ever since I got turned on to ebikes. As far as I can tell (at least by searching like a madman online) there are no other documented builds with a BBSHD on this frame. These bikes are also pretty hard to find used. So when I saw a lightly used 2015 size XL pop up on Craigslist here in Boulder, it was a no-brainer!

    Both of my other bikes have carbon shark batteries... which I love, but the case was just a little too tall to fit in this triangle. My bro in law has a regular shark pack, so I was able to use his as a tester and discovered that by reversing the rear shock I was able to get about 1/4" more clearance with the lockout arm out of the way. This allows the shark pack to fit with about 1/4" clearance. I knew it was going to be a gamble by the time I got the mount in there, and I still wasn't sure how much room would be necessary to remove and insert the battery into the cradle, but hey, taking risks and experimenting is half the fun! So I took the plunge and ordered a BBSHD kit with a 52V 11.5ah Shark. While I was waiting I did research on the bottom bracket and what it was going to take to get the motor in there. I knew it was a press fit 41 x 121mm. So, the 120mm BBSHD was the logical choice. There are a few different methods of getting a BBSHD to fit into a press fit bracket. I stumbled upon this part while not cheap ($75!) it seemed like the most straightforward answer. Matt was really cool, and talked me through the installation, which was super easy. They are basically big spacers that go on either end of the bottom bracket shell, to shim it down to the size of the BBSHD axle. Here is a shot of the motor side of the drive with the spacer and o-ring in place.

    Here's the other side...

    Here is the spacer when fully inserted in the bottom bracket shell, flush! With plenty of threads, in fact, all of the threads.

    Nice and snug! The spacer with the divots lined up perfectly and took a nice bite into the bottom bracket shell.

    At this point I was pretty darn stoked on how everything was coming together... that was, until I put my beloved mighty mini chainring on, and had a look at the chainline... yikes!

    This was pretty much not going to be safe under power, so I lamented and researched my brains out trying to come up with a solution. I attempted to space out my cassette by taking some of the lower cogs off, and using them as spacer behind the granny gear, to try and bring the chain closer to center... but the derailleur just wouldn't clear the gears when they were any closer to the swing arm. Plus, the chain stay is pretty tight, and the chain would rub on the chain stay when the larger cogs where moved outboard. I debated grinding down the bottom bracket shell on the drive side, as I still had plenty of clearance...

    But, I decided against it because I didn't want to do any permanent damage to the frame that would not allow me to return it to stock... just in case the build didn't work out. Luckily, I had also ordered a Luna Eclipse chain ring, which is truly a work of art! I was hoping to keep the Mighty Mini, as I love climbing steep ass singletrack on my other e fatty... And my plan was to try the Eclipse on my commuter, but in the name of a somewhat manageable chain line on the Bucksaw, I decided to give it a shot. Thankfully, it did wonders! I did have to use a couple of spacers on the drive side, because the teeth were just barely grazing the swing arm. I suppose I could have used a chain ring spacer, but that would have taken a few more days, and I still had plenty of threads on the non-drive side, so I figured it was the fastest was to get riding fast!

    I might still investigate some other options for getting the chain line under control with the mini... perhaps a SA 3 speed IGH with a custom 36 hole rim... but I'll wait and see how the Eclipse does on the trail first. I'm optimistic that it will be killer! On to the battery... I knew I was going to have to shave off the cable mounts on the down tube, so those zipped off pretty easily. Unfortunately I slipped and nicked the down tube a bit, but cosmetic injuries I can live with... This is going to allow the battery mount to sit flush against the tube... plus I needed every tiny bit of space possible to get the battery in there!

    To get the most solid mounting, I removed the plastic cover for the battery base, and drilled out some holes to line up with the water bottle mounts that were already in the frame. I also used some rubber bushings, that came with the kit this time, sweet This allowed me to really crank the base down, and it is solid!

    I was hoping to get a 3rd bolt into the down tube somehow for the top part of the plastic base. Unfortunatley, the triangle was too tight to get my right angle drill in there, so I came up with a solution that I think worked really well. I got some barrel nuts, and ran them through a hose clamp (wrapped in heat shrink tubing, but my heat gun was at home, so that will come later :) And then just wrapped that around the down tube and cranked it down. I used some sheet rubber to pad the down tube, and it compressed when I tightened the hose clamp. Seems rock solid! I'll still be using a velcro strap to hold the battery to the frame for added security, but this seems like a great way to get the battery attached without drilling any holes in the frame.

    I did have to zip the end of the exposed screw off with my grinder, but it took 1 second, and then with a small piece of 1/16" rubber sheet between, it sits pretty flush against the down tube.

    Here's the battery completely mounted. I do have to be pretty careful when inserting and removing it, but it does clear without touching anything... just barely :)

    Next up was wiring everything and dialing in the cockpit. I really like to keep things clean and simple up front.

    I then installed the hydro brake cut off magnet on the front brake. I have found this works far more reliably for me than the gear sensor. I just pretend I'm on my moto, and the front brake is the clutch, simple and I can be sure that the shift will happen before I sent power back to the drive. Sometimes with my commuter bike, the timing on the gear sensor is not long enough, and it will slam back on the power before the shift is complete. I just use the clutch-brake method exclusively now.

    I ended up zip tying the sensor to the brake body, and then drilled a screw through a knob on my brake lever. Seems pretty solid, we'll see how she holds up after some high speed bomber runs!

    Pretty straight forward install of the speed sensor...

    In all, this build took most of the afternoon. I ran into a few issues here and there, but really that's just part of any DIY project. There's really nothing I would do differently, except for further investigating some chain line fixes for the mightly mini. I took her out for a quick screamer, and damn was it awesome! It's only 20 degrees or so right now, and dark, so the real test run will come tomorrow. I am stoked that this project finally came to life after debating over it for months. I'm sure you guys know what it's like loosing sleep over mods :) So here she is, in all her full-fat glory! The Salsa Bucksaw with the BBSHD and Shark Battery in the triangle... hallelujah! rock and roll!

    Attached Files
    Last edited by Rodney64; 02-27-2017, 06:23 AM.

    Nice. I especially liked the hose clamp to battery mount mod. It looks secure enough to ride hard yet easy enough to change for testing other batteries.


      Great job on the build! Ditto on the hose clamp workaround. Especially the shrinkwrap,cool.


        very nice build


          So jealous, very cool. My favorite f/s fat bike. What's it weigh without the battery?


            Originally posted by Harold View Post
            So jealous, very cool. My favorite f/s fat bike. What's it weigh without the battery?
            Yeah, thanks, super stoked! I have no idea what the weight is... pretty heavy with all the gear, but lighter than my Motobecane Bullet with similar components...


              perfect job. just bought a used buckksaw 2 from 2015 like yours. Is there a reason why you didnĀ“t use the adapter from luna like this or this ?
              I really like this bike, I want to change the rims to fit 4,6" tires on it and I try to get the original frame bag from revelate for building a custom batterypack with my spotwelder. On the other hand I have to say, that the sharkpack that you use looks also very nice. What sprocket size do you use?


                Super nice! I would love a bike like this. Thank you for your detailed description of the build.


                • Zippy
                  Zippy commented
                  Editing a comment
                  Todd if you can afford the ticket price that's the bike you want, super nice suspension fatty.

                I recently finished building a non e bike version. I used a 27.5+ fork instead of a Bluto. The JJ 26 x 4.0 tires clear the fork. I also run WTB 26 x 2.4 (actually clse to 2.6). Both tires work on 50mm rims.
                Occasional good deals come up on ebay for new bikes and frames.


                  Your post inspired me! I just got a medium frame Bucksaw and I'm installing it right now. Can you tell me where you got those spacers that go on either end of the bottom bracket shell to secure the motor with the o-ring?