2018 Diamondback Sync'r 27.5 BBSHD Build

[svenpup]

This build write up may be a little overboard, but I got so much help and inspiration from all the other posters here and on other sites that I wanted to make sure I gave something back. Enjoy!

Components:

• Donor bike: 2018 Diamondback Sync'r 27.5
  • Size M/18"
  • Boost 148x12mm Thru-axle
  • SRAM NX, 11 Speed (11-42 tooth cassette)
  • 73mm BB with ISCG chain guide tabs.
  • Note: I am specifically specking the 2018 model year here because johnnybags on reddit built an earlier Sync'r model and says he and didn't need any spacers. The 2018 version did need spacers, but not much. It is boost on the rear which may be the difference.
• Motor: BBSHD 68-73mm from Luna (stickered 68mm)
• Battery: Luna Wolf 52v 12ah 14s4p Samsung 30q cells
• Display: EggRider V.2 from California Ebike
  • Note: I originally ordered the 750c Full Color Display, but it didn’t fit on the Sync’r stock 35mm handlebar.
  • The EggRider is tiny and fits unobtrusively off to the side. Additionally is has Bluetooth to pair with an iPhone or android app and can program the controller in lieu of a programming cable. It seems like it is a little in the “beta testing” phase so maybe hold off if you are not tech savvy or have a lot of patients. Otherwise I think it’s great.
• Lekkie 42T HD Chainring
• BSBF-1 Bafang Stabilizer Bar from California Ebike
• Luna Right Full Twist Throttle
• Hydraulic brake sensors
• Shift Sensor

[svenpup]

Some additional items that really help (borderline necessities):

• J-B Weld SteelStik Epoxy Putty
  • Saw this used on someone’s write-up as a buffer between the BBSxx and the down tube. I planned on using it anyway, but since the boss for connecting the triangle bracket hits the extra wide down tube it was a necessity. (more below)
• Self-annealing tape
  • (also called silicone-rubber tape, self-vulcanizing tape, centerline tape, F4 tape, etc.)
  • I can’t believe I am just finding out about this stuff. It is non-tacky and will not stick to the surface. It sticks to itself and unites itself into a strong, seamless, rubbery, waterproof, and electrically insulating layer.
  • It is great as tie wraps to keep cables tidy
  • Wrap around the chain stay as protective tape
  • Use it to secure the magnet and sensor for the brake sensors (more below)
• 3M Automotive Molding Tape
  • Should be a staple in every garage
  • Use it when you have to readjust your brake sensors and the single piece of crappy tape it comes with doesn’t stick any more.

[svenpup]

Thoughts on the Sync'r for eBike conversion:
Impressive value priced, well built, and capable bike, if somewhat heavy. I really like the 1x11 SRAM drivetrain for a BBSxx conversion. Pretty good chain line. I was planning on re-sorting the cassette, but in hindsight I think I will leave it. The lowest gear (42 tooth) is hardly ever needed and the mid-range with good chain line seems to cover the vast majority of needs.
Warning: You will have to grind down the tab on the ISCG chain guide. If you are not ok with grinding on your frame this is not the donor bike for you.
If you are going to buy a diamondback online be sure to sign up for a corporate account. A quick google search for a code to sign up and you can save 30%.
Note: It has a wide, hydroformed down tube and the boss for connecting the triangle bracket WILL hit the frame. More on how I dealt with this later.

[svenpup]

Thoughts on Luna:
I am pretty impressed with the quality and just look at that packaging.

[svenpup]

ISCG chain guide tabs:
One of the tabs will hit the BBSxx housing and must be ground down. I used a dremel, but I have seen others use a bench grinder. If you are not ok with grinding on your frame this is not the donor bike for you.

[svenpup]

BBSHD thread issues:
The threads where the triangle bracket screws in were buggered up. I was concerned that if I used a regular tap I would mess up the threads, but I couldn’t find a thread chaser so I built my own. I knew I would need the longer bolts to accommodate the 73mm BB, so I was free to sacrifice the shorter bolt. Using my Dremel I ground several slots down the length to allow cut material to escape. Then I tapered the end for easier insertion and centering.
Then I carefully screwed my hand made thread chaser into the threads, a little at a time, backing back out frequently. Especially at the beginning it is important to keep the thread chaser vertical and ensure it is not cross threaded.
When cleaning up the blind hole I held it upside down so the cut material didn’t fall into the hole. Worked like a charm!

[svenpup]

Bottom Bracket Spacing:
I used 4.33mm of spacers on the drive side to avoid contact with the chain stay. I ended up with exactly enough thread on the other side to allow use of the jam nut (I still used Loctite anyway). The spacer kit from Luna only comes with 3mm spacers now, despite what their website shows. This means that with Luna’s spacers your options are 0mm, 3mm, or 6mm. I had to get extra spacers (including the 1.3mm) in order to minimize outward spacing. If I had gone with 6mm I would not have been able to use the lock nut.
Note: I think the triangle bracket is thicker than the stabilizer bracket I used (see below). I suspect that it would not be possible to use the jam nut if the stock triangle bracket was used.

[svenpup]

Boss interference & SteelStik Epoxy Putty:
As I mentioned above, the Sync’r has a wide, hydro-formed down tube and the boss for connecting the triangle bracket WILL hit the frame. I formed about half a tube of SteelStik into a ball and placed it where between the housing and downtube. Then I slowly pressed the housing down until the spacing was to my liking.
Note: I used parchment paper (love raiding the kitchen for garage projects) to prevent the putty from sticking to either component. Without the parchment paper you would be epoxying the whole thing together.
I left the whole thing in place for a few minutes to let it set up.

[svenpup]

BSBF-1 Bafang Stabilizer Bar from California Ebike:
I was never impressed with the little “teeth” on the triangle bracket being the only thing preventing the BBSxx from spinning. Seems like the weak point in the whole design to me, especially with an aluminum BB. I saw horror story posts of aluminum BBs chewed to bits. I ordered both the BSB-1 and BSBF-1 versions to experiment with which worked better. The manufacture pictures of the BSB-1 show it connected to the chain stay, but this positions the BBSxx to be hanging very low. I saw other people connect the BSB-1 to the seat tube, which can give better positioning of the BBSxx, but this is dependent on the angle between the angle between the seat tube and down tube. In my case it was close, but I preferred the positioning with the BSBF-1. I did have to grind a notch out of it so it wouldn’t be resting on a rib on the BBSHD housing. I put down a layer of the self-annealing tape to protect the down tube from the stainless steel bracket. Then I used a hose clamp to secure it, and wrapped the whole thing in another layer of self-annealing tape.
At this point the only thing left to do on the motor install is torqueing down the nut and jam nut.

[svenpup]

Brake Sensors:
I used some of the self-annealing tape (cut into thin strips) to give more security to the sensor and magnet. It worked great and I am confident they will stay in place.

[svenpup]

Final Thoughts:
Building an electric bike like this, rather than just buying one, has its pros and cons. You can select exactly what you want for components and potentially do a better job than someone manufacturing one. It terms of dollars spent I feel like I got a lot of bang for the buck. I am sure it will smoke any hub drive out there, and probably any stock mid-drive. I am planning on putting the myriad of extra parts I had to buy on eBay to recoup some costs, but I am probably in for about $2,500 when all is said and done. That being said, if I was paying myself for hours spent, this would have been a $30,000 bike.
For anyone interested, the final weight is 51lbs.

[Stavros]

Very nice build svenpup!

I would like to Know more about the connection between the battery pack and the motor (did you use connectors?) and about cable management.

[svenpup]

Very nice build svenpup!

I would like to Know more about the connection between the battery pack and the motor (did you use connectors?) and about cable management.

The Luna wolf battery has a female XT-90 anti-spark connector for the motor and female XT-60 for the charger. The BBSxx has an Anderson connector. The XT-90 is a much superior connector for this application. Luna included an Anderson-to-XT-90 adapter, but I prefer to not use adapters so I cut off the BBSHD's Anderson connector and soldered on a male XT-90.

As far as cable management, I used lots of the self-annealing tape I described above. I prefer it to zip ties. Tidying the cables will be unique to each build base on bike geometry and cable length, but in general just make sure everything is secured out of the way.

[Stavros]

Thanks for the reply svenpup, be aware that when you take the battery out of its holder there is still high voltage at the battery holder connector due to charged capacitors inside the controller. You can measure it using a multi meter. So there is great danger for a sort circuit because most battery holders have male connectors. A sort circuit like that is probably very dangerous for the controller and to be able to disconnect the XT-90 connector is the safest way to go.

[Electron Flow]

This was a very valuable post for my first build. This message is simply to say thank you for posting the build information. I built my first e-bike using the BBSHD kit from LUNA and the Diamondback sync'r. This bike does around 32 MPH in OFF-ROAD mode (eggrider V-2). I Did end up purchasing the battery via amazon though. Luna had been sold out for a bit for the 52V that I wanted.