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Second Build: Motobecane Boris X7 with BBSHD

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    Second Build: Motobecane Boris X7 with BBSHD

    I've been meaning to write up a post-build log of the e-bikes I've done so far, but I'm going to start with the second one since that is more fresh. I found out that this forum was now opened, so I figured that was good timing. My first foray was mostly done as a proof-of-concept for myself (and my wife) to see if an e-bike was viable for my uses. Since I was trying to do the first as cheaply as possible while still being fun, it was a 1000w rear hub DD kit and a 48V 20ah battery from Lunacycle. That, however, is another story for another time. This is about the second bike I put together...

    After using my first bike for a while, I found that it was:
    • A lot of fun
    • Not enough for some of the steep hills I ride on (with my fat ass)
    I wasn't looking to go any faster on the flats, but I did want a bit more steep climbing capability so I started looking into mid-mount motors. I had been doing research for a while and nearly pulled the trigger on a BBS02 750w, but then one night as I was sleepily browsing the endless-sphere forums, I heard rumours of a soon-to-be released 1000w mid from Bafang. I decided to hold off for a while since it was getting to be fall/winter and I wasn't going to be riding a lot during the winter. I kept watching the forums and various e-bike sites while more info started coming out and found out that Lunacycle was going to be offering the BBSHD for pre-orders. I probably went a bit overboard, but since I didn't know how many would be available right away, I set up programs to watch Lunacycle's mid-drives page for changes so that I knew within a couple minutes of them being available. I was probably one of their first pre-orders.

    Here is a list of things I needed for this build along with approximate price:For a grand total of $2111 for the things I needed to complete the build. This can obviously be done a bit cheaper by going with an even cheaper bike, skipping the chainring, cheaper battery, and the motor is cheaper now too...

    Additional things that I didn't need, but wanted to add for either fun or comfort:So, about an extra $160 for now. I'll be adding fenders soon, and upgrading various other components, but that's the nature of the beast...

    I had decided that as long as I was going e-bike, I might as well get something fun and not worry so much about weight, so I decided to go with the 100mm bottom bracket BBSHD version and find a fatbike to put it on. This is not the right way to do this, but I got lucky. I looked around for a fatbike and finally settled on the Motobecane Boris X7 due to having good luck with BD in the past. If you don't mind working on a bike, they are a pretty good value.

    So, donor bike:

    How it looked when it arrived:

    After some assembly and after I removed the front derailleur and crankset:

    BBSHD slid into place eventually. It was a very snug fit and I chipped up the paint a bit while rotated it to get it all the way through. If you are seeing that part of my bike, things have already gone very wrong anyway... The drive side housing is very close here. It ends up being pressed against the frame after I tightened the drive on but the frame didn't seem to be applying much pressure or bending anything so I left it without a spacer. You can also see the wrench I used for extra leverage on the BB tool while removing the factory installed bottom.

    I also opted to get the Luna Eclipse chainring in black. I ended up having to use about 4mm of spacer between the chainring and motor to keep the chainring from hitting the chainstay. The spacer from Lunacycle was just a little too small at 3.3mm. Rather than grinding down the sides of a stack of washers as Karl (from has suggested in one of his articles, I ended up using some nuts that had just the right diameter that they slid over the bolts for the chainring. Since the outside diameter of the nuts was smaller than a washer would have been, they fit perfectly in the space on the motor side. They were also somehow miraculously the perfect spacing I needed to keep the chainring from rubbing the stay. I only ended up needing one washer on each of the bolts holding the motor bracket to get the bb part flush so the little ridges that go against the bottom bracket would have as much bite as possible. There is now about 1mm of clearance between the chainring and chainstay. This picture is from before I tightened everything down: Click image for larger version

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    Here is a video I made after I had everything together enough to test out the motor. I'm sure there is a fancy pronunciation for Motobecane, but I don't know it. Yes, my wife is awesome and doesn't complain too much when I do this in the living room and use her piano bench as a mini work bench...

    I had chosen to go with the C965 display because... bigger number? I don't really have much preference on the different displays, and the DP C10 wasn't available at the time. I'll probably be upgrading to that in the future and have the C965 for backup.

    I did have a problem with the speedometer that I have also read about from others where it goes a little wacky over a certain speed. I've since done some experimentation with placing the magnets closer to the hub of the wheel and this seems to increase the speed at which it goes out. When I filmed the video, it looks like this was around 40-42mph (I'm using another trick from Karl here and using a tire size of 18" in the settings so that when the display shows kph, it is actually a close approximation to mph). With the magnets closer to the hub, the wackiness doesn't start until nearly 49mph - which should be way, way faster than this bike ever sees in real-world use.

    The crank arms are Schlumpf 170mm arms that I got after reading so much bad press about the stock Bafang arms. I'm not sure what they are made from (and couldn't find any composition info on them), but they are fairly wide and flat and seem pretty beefy. I also got a new chain since the stock one was a couple links too short with the 42T ring up front. It wasn't happy shifting in/out of the lowest gear and was basically just the straight tight loop from the front to the rear. I went with the KMC X10E chain that is supposedly made for e-bikes. We'll see...

    Fast forward a bit and I've got everything put together. I went with a 52v 11.5ah (for the higher amps) shark pack from Lunacycle because they look pretty nice and I wanted this bike looking fairly clean. In another one of the *just barely fits* miracles on this build, the pack comes to rest against the seat tube when it is seated on the base, but it is all the way onto the base and locks in place. Click image for larger version

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    Click image for larger version

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    I've only got about 30 miles on it now, but it has been great so far. The drive is very quiet and I can't hear it over the tire/drivetrain noise. The PAS is pretty nice, but I have to set it to 1 on the bike trails to keep the speed reasonable and still be able to be giving input. I may play around with the assist levels at some point. The steep hills that were brutal on the hub motor are fairly pleasant now and I can get up them about twice as fast with a lot less effort. I haven't tried, but I probably wouldn't need to pedal at all, which would have just melted the hub motor. I'm not sure what the top speed is yet, though it is dependant on gearing. I've been up to 35mph on a slight downhill which is about as fast as I ever intend to get it, so it is more than fast enough for the riding I plan on doing. Usually, 15-20 will be just fine with occasional mid-high 20s.

    There are several things I still want to change - tires, seat/seat-post, fenders, tidying wires - but it is a ton of fun to ride.

    I'll do a write up similar to this for my first build of my hub-motor bike in the future and I have a couple things that I think would make good posts about my wiring for my lights.
    Last edited by Sisyphus; 02-19-2016, 03:28 AM. Reason: Links, formatting

    hey thanks so much for this write up. I have moved it over to the build instructions category. The idea is someoone coudl buy this exact frame and BBSHD and have an idea of how to build. Sometimes you just dont know if the parts are going to be compatible with the bike you chose.


    • Sisyphus
      Sisyphus commented
      Editing a comment
      Thanks, Eric. A friend of mine let me know that several of the pics weren't showing up (maybe the forum ate them? I can't attach them to the post anymore either), so I fixed that and they should all be showing up now.

    Holy Crap!! Thanks for posting this. I like the low top-bar, because I am not a fan of slipping off the seat during a hard stop and landing on my niblets. I'd rather my feet hit the ground first. There are so many frames that have minor variations and one drive has an issue fitting. It may not even be a huge problem, but its nice to know ahead of time if there is an issue, and also a particular solution that fixes it...BEFORE ordering the bike and kit.

    I am planning on building up a BBSHD soon, It is my new favorite drive (on paper). But...I need to actually get my hands on one and get my fingers dirty.


      Nice build. I like it for it's simplicity.

      Curious about the wheels. One thing I found with my eConversion was that I think wheels are often overlooked. Mine was a road build for commuting here in Portland where we have steep hills, etc. The wheels I had were stock Bontrager and honestly with a BBS01, they couldn't take the stress. I'm wondering what spoke configuration you have with this - are these 36s wheels?

      Last edited by DrDave; 02-21-2016, 09:45 AM.


      • Sisyphus
        Sisyphus commented
        Editing a comment
        For now, I just have the stock 26" wheels but the outside diameter of the fat tires end up being similar to normal 29ers. The spokes needed some tightening, but they weren't too bad. I'll probably upgrade the wheels at some time, though, since the tire/tube/wheel/hub area is definitely where Bikes Direct tries to save some money and go with cheap components.

      You noted that after tightening the nut the housing on the R side was pressing up against the frame. My ADD brain makes me overthink everything, making everything more complicated that they should be perhaps. But I do wonder about vibration at that contact point. You could put in a small spacer on the R side that wouldn't compromise the setup much - it wouldn't create much of an offset with the chainring or prevent you from tightening down the lock-nut. Just some confabulations - probably no biggie...just know that vibration could be an issue at some point.

      This might be a good thing for Eric to consider stocking, honestly - a series of rings, say 2, 3, 5 mm that can be used. It seems this is a constant issue for folks to engineer.


      • PoweredRide
        PoweredRide commented
        Editing a comment
        I agree best to use a spacer and not let it touch. Mine was touching a suspension hinge but I didn't have any spacers. I did have a bottom bracket lock nut about 4 millimeters thick that fit perfect.

      Thanks for the great info!

      I found your post after reading Karl's , and thinking about doing the very same build.

      When I saw that you'd already done it, that convinced me that the 100mm BBSHD would indeed fit a Boris X7 without extensive modification.

      It was a tight fit alright. I used some steel wool on the motor spindle and a little bit of lubricant to slide the motor into the crank bracket, with a 1mm spacer to keep a slight clearance between the motor housing and bike frame, while still ending up with a decent chain-line.

      The kit from Luna Cycle also came with an assortment of other spacers too.

      Will post some photos shortly.

      Thanks again


        do you think it would have been better to get the 120mm kit instead...wanting to start my build


        • Sisyphus
          Sisyphus commented
          Editing a comment
          I don't think so in this particular case. The 100mm fits almost perfectly with a couple mm to spare for a spacer on the drive side to move the housing away from the frame. If you have a frame with a really wide chain-stay, then you might need to go to a 120, but on the Boris frame the 100mm fits great.

        I have since added the 2mm spacer from Luna and (not surprisingly) have about 2mm of clearance between the housing and the frame now. I could probably have gotten away with the 1mm spacer, but I figured 2mm would be fine and then I can use the 3.3 chainring spacer if I go back to the 42 tooth eclipse. I've currently swapped to the Mighty Mini chainring (and quickly let the torque go to my head...) for the hill climbing and derailleur shredding capabilities.


          Thanks! This post is now a saved page of mine because I was looking for info and more on the BBSHD install on a fat bike. The pics help slot! The bike I'm setting up is the moongoose dolomite. Currently I have the kit and bike back at home and waiting for me to get there and start the build. I ordered early June but I don't redeploy home till July. Going home present to myself.
          Life Behind Bars


            Here is a youtube I found documenting a BBSHD build on the same Motobecante Boris.


              Hello -

              Thank you for taking the time to post this build! I have a question... You have used the Schlumpf crank arms to replace the Bafang arms. Do you know if the original arms would have cleared the chainstay on this frame?

              I am helping a friend put together a build using the BBSHD 72-100mm kit he has purchased via the current 'Black Friday' 2016 sale. He does not have the bike yet. I would like to be able to give him good information on which bike to get so we do not spend a lot of time and extra $$$ buying additional parts. The site seems to have a bunch of fat tired bikes with the 100mm bottom brackets but in spite of reviewing various build reports, I am not confident as to which bikes will accept the kit without mods and/or extra parts. This one appears to be about as good as it gets (as far as fit) for the 4" wide tire fat bikes.

              If the Bafang crank arms will clear the chainstays, I will likely advise that he get this one. If you (or anyone else reading) know of a similarly priced fat bike that accepts the 100mm BBSHD without cutting/grinding/buying extra parts, please feel welcome to respond.

              Thanks in advance!


              • Sisyphus
                Sisyphus commented
                Editing a comment
                As far as I can tell, the crank arms that came with the BBSHD kit would have also worked just fine. The only reason I picked up the Schlumpf arms was because I had read about the default ones being stripped easily. A friend of mine built up a Surly Wednesday with a BBSHD and used the default arms and had no problem as well.

              • john mellor
                john mellor commented
                Editing a comment
                OK - Thanks for the info! FWIW my friend bought a Framed Minnesota2 and the 73-100mm kit fit fine. No pedal or bottom bracket modifications were necessary. We used a single spacer on the drive side just to keep it clean but I don't think it was necessary. The original bike came with a pretty small chainring so the chain is a bit tight with the larger Bafang chainring. He is able to ride in the higher gear ratios however the derailleur is maxed out before hitting his lowest gear. A longer chain is on order. We drilled out a single hole in the aluminum part of the battery cradle to allow for a repositioning of the battery which was hitting the seat tube at the bottom end. So.... a longer chain and repositioning the battery cradle were the only mods needed. His wife ordered a kid's sized version of the same bike and the battery pack is a definite 'no-go' inside the frame triangle. She will need to mount her battery pack on a rear rack. That is one bugaboo I can see with some bikes... it's hard to judge ahead of time exactly if the battery cradle will fit on the water bottle mounting bolts and still allow enough movement to lock the battery in place.

              Looking to do a build of this type. I AM A NOOB !. This looks like a doable for my skills build. This is a year old post any updates or links to more and improved parts or methods. I am buying the donor bike so am not locked into this build. Flat roads dirt and paves shoulders of roads possible two track . Need the fat tires but like the upright riding position. Just sold my peddle Monster ltd now need a e-bike. Was going to buy Rad Rover buy would like a more powerful bike for about the same money. Advice and comments appreciated.



                Thanks for sharing your build. Just finished my first build last week following this with some minor adjustments. I have a 19” frame and went with the 52v 13.5 amp/hr shark pack that fit the bottle mounts on the bike just barely. There were some burrs in the bike after I took the stock crank off that needed to be filed before the BBSHD would slide on. I didn’t need to use any shims anywhere. The motor is touching the chainstay, but wasn’t until I tightened the bolt. You could shim it, but I didn’t feel it was necessary. I used the stock crank arms. I ended up using the 36t Lekkie bling ring for the extra torque to climb hills. Using the 36t chainring also allowed me to use the stock chain and save a few bucks there. Nothing was really too difficult, I have minimal experience working with bikes. The brakes on the x7 suck but they work. I’m also not used to a bike with no suspension so it’s been a little rough, but I didn’t want to pay for a Bluto fork bike. I plan on going tubeless soon and take the tire pressures down to around 8-10 psi which I believe will help. Anyone have any experience with a Thudbuster seat suspension? Is it worth the cost or would my money be better spent on the Luna Lander fork?
                Last edited by bbauman05; 12-28-2017, 09:09 PM.


                  I did a boris build too

                  Click image for larger version

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                    I got a 2018 Boris the Brut Large Frame...I got the one with front and rear thru axles. Im putting my kit in right now. I went with the 120 bbshd, I will need 2 10mm spacers on each side of the motor that a retired machinist neighbor is going to help me out with. But, just looking at it if I had went with the 100 bbshd on this kit the motor would be significantly off center and the non drive side pedal would hit the chainstay. Really lucked out ordering the 120 and not going with the 100.
                    2018 Motobecane Boris Fat Bike BBSHD Build


                    • xcnick
                      xcnick commented
                      Editing a comment
                      Tell us if the spacers work to hold the motor in place. I use a 120 with spacers and have had to use a torque arm no matter how hard I tighten up. The 120 gives a different Q factor left and right. I think there is an offset crank for the non drive side you could use on the 100. I am still not sold on the 120 and would like to try a 100.

                    • pure_mahem
                      pure_mahem commented
                      Editing a comment
                      was that the torque arm they show on Luna or a different source? I was looking at getting one of the ones Luna stocks.

                      I think no matter what I'm going to go with a torque arm. But upon looking at the problem, all can really do at the moment lol, a Ah Ha Thought came about. I was originally thinking to put the spacer between the bottom bracket and the fixing bracket. Mainly because the spacers Luna gives you for mounting the fixing plate to the Motor. I see this as a mistake. As you say no matter what I would of done would result in motor slippage.

                      Im now thinking to put the fixing plate directly against the bottom bracket and use washers to create the proper distance between the motor and the fixing plate. I will still need the 10 mm spacers but I can put it between the fixing plate and the M33 Nut still get the ability to bight into the bottom bracket.

                      When I add the torque arm Im thinking i will just add it on top of the fixing plate and not instead of...not sure if that's how it was intended to be used or if it was intended to replace the fixing plate. Ill have my neighbor make me up a 5mm and 7mm spacer as well to use this way.

                      Thinking I will order both of these and see which one I can get to do the job best perhaps even using both.
                      Last edited by pure_mahem; 02-18-2019, 09:52 AM.