Bafang Ultra Fatbike build

[Daxxie]

After building some BBSHD bikes it was time to get my hands on a Bafang Ultra drive.
I like the torque sensing idea and the integrated look of the G510.

Ordered a Ludicrous Ultra from Luna.
And found a titanium frame on Alibaba.

Exchanged quite some mails with "Linda" the very helpful salesgirl.
Frames are completely custom build.
I don't know much about bike geometry so went for a quite basic frame. (Large)
If I had to do it again maybe I would go for a smaller chain stay, a Rohloff mount and I would have moved the mount for the speed sensor a bit more backwards.

Delivery should take 45 days Linda said (as it was one week before Chinese new year) but I wasn't in a rush so I ordered a frame, seat post, handlebar and a titanium headset.

Frame was ready after 50 days but that interfered with my holiday so had the shipping postponed for a couple of weeks.

The frame was very well packed and arrived without any damage or scratches.

It felt very light but you could notice that the bulk of the weight was in the motor mount bracket.
I thought some extra weight could be saved there by drilling and grinding it down a bit but that was before I discovered how tough Titanium is.
Even my best drills had a hard time of making a small hole in it.

Frame weight was 2.75kg

[Daxxie]

I'm planning on building a custom battery for this bike later but I also had 4 mounting holes placed on the downtube to securely install a Jumbo Shark.

I would like to hide the cables as much as possible.
Thats why the motor mount bracket needed some extra holes for:
2 power cables
Derailleur cable
Speed sensor cable

The gear sensor will be installed in the downtube.

[Daxxie]

Parts I ordered for the bike:

Magura MT5 + MT5e (I only want a brake sensor on the rear brake)
203mm and 180mm brake discs

Also found a nice "cheap" secondhand wheelset from DT SWISS with Fatsno Pro4 hubs
150x15 197x12
Didn't like the black rimtape and changed it to Neon Green.
Wheels came with 4.0 tyres I ordered some 4.8's


I lended the Bluto Fork and SramX9 derailleur from my scott fatbike, later will find another Bluto in a different colour.

[Riderofbike]

Nice build. How much will it have cost when it is complete?

[ncmired]

Nice build. How much will it have cost when it is complete?

Meanie! ;-)

Congrats and good luck on your build, Daxxie. I think titanium has some pretty vicious galling tendencies, worse that stainless steel - is this correct?

For others looking, here's the (for right now) alibaba frame link: https://www.alibaba.com/product-deta...21791d54ThrSCe

[weetard]

anyone still around this thread?

[MoneyPit]

fantastic!
Daxxie what happens if you were to NOT drill those holes? I'm looking at the pics on the Luna site and it appears that there is a drive-side plastic motor covering that hides the rats nest of connectors... the wires would ordinarily run out thru some kind of hole in that? Maybe in the back? And then route out as needed to their destination?

The holes allow you to route cabling in different directions under the mount and fwd out to their individual destinations? Did you replace the cabling with Higos to allow for those small holes? Looks like the stock connectors are JST based on what I am seeing at Luna.

[Daxxie]

Nice build. How much will it have cost when it is complete?

Oohh, didn't calculate yet.

Roughly:

Frame, handle bar, seatpost, headset + shipping 1200usd
Bafang Ultra Ludicrous + Thumb Throttle and some other stuff + shipping 1200usd
Secondhand wheelset 300€
Magura brakes 160€
Other small stuff 200€
Bluto fork I took from my other bike
Battery: I will use the shark of my other bike for now.

[Daxxie]

fantastic!
Daxxie what happens if you were to NOT drill those holes?
Did you replace the cabling with Higos to allow for those small holes? Looks like the stock connectors are JST based on what I am seeing at Luna.

Yes they are JST's. There is only 1 electric cable with JST that goes to a drilled hole (the speed sensor)
I cut it and resoldered it.

2 Power cables go straight up to the battery. I drilled those in the motor mount. Downtube could have been possible also but that would weaken the frame too much.

The main harness goes up the downtube and comes out in the provided holes.

Only tricky part is the derailleur cable. Goes in on the top of the downtube, connects to the gear sensor hidden in the downtube, runs over the motor and exits the motor mount at the drilled hole at the back straight to the derailleur. Hope that will work without to much friction on the cable.

[Daxxie]

Some updated pics.

[Riderofbike]

Nice bike.

[ncmired]

Forgot to ask - is the motor mount cast titanium - did the frame builder make that too? If so, wow, they're well equipped ...

[Daxxie]

Forgot to ask - is the motor mount cast titanium - did the frame builder make that too? If so, wow, they're well equipped ...

Sure, full titanium.

[Daxxie]

Wanted more power!!!
Installed a phaserunner in the drive.

[Daxxie]

[weetard]

Wanted more power!!!
Installed a phaserunner in the drive.

amazing build. is installing the phaserunner something a newb could do?

what are your speeds and battery life with this setup?

thanks