Titanium Fatbike - Bafang Ultra and Phaserunner

[Daxxie]

Hi Sphere!

Here some pics and a build thread of my Fatbike with Bafang Ultra + Phaserunner.
I started the build in July, its almost complete now.



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. (As it turned out later, it wasn't a Ludicrous)
And found a titanium frame on Alibaba.

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 chainstay, a Rohloff mount and I would have moved the mount for the speed sensor a bit more backwards.

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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.

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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 wanted 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.

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[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

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.

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Didn't like the black rimtape and changed it to Neon Green.

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Derailleur cable runs between motor mount and the Ultra drive

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Nice clean look.

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[Daxxie]

Bike runs great but the power of the "Ludicrous" Ultra was dissapointing.
After checking settings, wattage and amps I could only conclude that this was a standard drive.
Display went up to a nice 1500W 30A, where the Ludicrous only should indicate 1250W and 25A (x2)

After some mails to Luna they agreed that I got a standard drive and gave me a refund.
What now?

I have a BBSHD Ludicrous bike which is a lot faster then this.
And I really wanted some extra power.

Would a phaserunner fit inside an Ultra drive?

Only one way to find out.
I ordered a CA3 and a Phaserunner and took some measurements.

First I hooked it all up and did some tests.

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The Ultra runs quite well with the PR.

The Phaserunner is about 1cm to big to fit inside the Bafang drive.
With a little modification (hacksaw!) it might fit.

The PR can be shortened a bit.

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And the motorcasing needed some milling.

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[dirt huffer]

Looks awesome!

[soaresdacosta]

Top work.

[Daxxie]

How I wired it:


Phase
Phase wires go to Phase wires on Phaserunner

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Hall
Hall Connector has 6 wires.
5V and Ground + 3 Hall sensors and a white cable that is a NTC thermistor that I connected to the CA to monitor the temperature.

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PAS
It took some time before I figured this one out.

The Ultra's PAS needs 5V, you can steal 5V and ground from the CA or from the Phaserunner. (There is 5V and ground at the PR throttle connector.)
The CA didn't pick up the PAS signal from my Ultra. I had to add a 20K pull-down resistor between Pas signal and ground to make this work.
The Green Dir cable is not used
The Purple Pas Phaseshift is connected to the dir tab on the CA
Brown Torque goes to the Trq on the CA.

My Ultra had a Higo6 connector for the PAS with the right colours, which made it a bit easier.

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This is a diagram I made:

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I used the standard Bafang Speed sensor.
Gearsensor and 1X Magura MT5e rear brake.

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[Rube]

Outstanding write up, thanks for sharing this information. Much milling did the case? Looks like a .5mm on the large section. Please let us know if/ when you hit thermal protection on the phaserunner. Cheers

[dutchlincoln]

hi, my son and i followed your thread with a big big smile on our faces!
Gorgeous build!
Can you tell me where you got the frame (and wheels and motor?)?
i'd like to build something similar.

Looking forward to hear, thanks ahead.

Great build!

[fechter]

That's a really nice looking frame.

The controller in the Ultra has been a problem for quite a few people. With a decent external controller it should be very good. The rotor is substantially larger than the one in a BBSHD.

[Daxxie]

Some Ultra motors have the white connectors for PAS/Torque.
How to determine which wire is which?

Thanks "Ivanovitch_k" for the pic!

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+5V and GND is easy.
You can see it on the backside of the controller board.

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I still have a picture of my plug that will make it easier.

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orange | purple | white
black | brown | green

These colors correspond with :

+5V | Pasphase | PAS
Gnd | Torque | Speed/Dir

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You can check with a multimeter

Between Gnd and PAS : gives you a pulse signal when rotating the crank FWD and REV 0V | 5V | 0V | 5V etc...

Between Gnd and PASphase : gives you a pulse signal when rotating the crank FWD and REV 0V | 5V | 0V | 5V etc...

Between Gnd and Speed/Dir : gives you a pulse signal (0V or 5V) when rotating the crank FWD and 5V constant when pedaling backwards

Between Gnd and Torque : gives around 1V and a bit more when you put torque on the pedals.

This is a video I made from PAS and Speed/Dir signal on a scope.
(Top signal is PAS, bottom is Speed/Dir)

[Daxxie]

hi, my son and i followed your thread with a big big smile on our faces!
Gorgeous build!
Can you tell me where you got the frame (and wheels and motor?)?
i'd like to build something similar.
Great build!

The frame supplier I already mentioned above:
https://bjcsti.en.alibaba.com/product/6 ... G510.html

I bought one Bafang Ultra from Lunacycle
https://lunacycle.com/bafang-ultra-magn ... mid-drive/

And another one from CNEbikes. They were quite cheap.
660USD incl shipping to Europe and all taxes paid.
https://www.cnebikes.com/product_catego ... -1000.html

With the wheelset I was quite lucky. Found them secondhand on ebay for 300€
- DT-Swiss BR710 (changed the rimtape from black to Neon Green)
- Hope Pro 4 Fatsno 150x15 -197x12 (I don't like them. Terrible clicking sound and too much backlash)
- Jumbo Jim 4.0 (I replaced them with 4.8's)

Phaserunner from:
https://fasterbikes.eu/en/controller/31 ... oller.html

Higo connectors:
https://www.e-bike-technologies.de/inde ... ctors/higo

[dutchlincoln]

hi, my son and i followed your thread with a big big smile on our faces!
Gorgeous build!
Can you tell me where you got the frame (and wheels and motor?)?
i'd like to build something similar.
Great build!

The frame supplier I already mentioned above:
https://bjcsti.en.alibaba.com/product/6 ... G510.html

I bought one Bafang Ultra from Lunacycle
https://lunacycle.com/bafang-ultra-magn ... mid-drive/

And another one from CNEbikes. They were quite cheap.
660USD incl shipping to Europe and all taxes paid.
https://www.cnebikes.com/product_catego ... -1000.html

With the wheelset I was quite lucky. Found them secondhand on ebay for 300€
- DT-Swiss BR710 (changed the rimtape from black to Neon Green)
- Hope Pro 4 Fatsno 150x15 -197x12 (I don't like them. Terrible clicking sound and too much backlash)
- Jumbo Jim 4.0 (I replaced them with 4.8's)

Phaserunner from:
https://fasterbikes.eu/en/controller/31 ... oller.html

Higo connectors:
https://www.e-bike-technologies.de/inde ... ctors/higo

Great info, thanks!!

About the motor: I thought you ordered a 2500 watt but got a lighter one instead? The one in the link is the 1500W model, correct? Is the Phaserunner still needed then?


Just saying once more: Great build, i love it!

[nataS@phnet.fi]

You sir, are a madman! Great work!!

[Mick48]

What was the conclusion of installing the phaserunner? Does it help smoothness upon signal or
increase power? Just curious. BTW, beautiful build and great ideas!

[Daxxie]

What was the conclusion of installing the phaserunner? Does it help smoothness upon signal or
increase power? Just curious. BTW, beautiful build and great ideas!

I had a Bafang Ultra with a faulty controller.
Spare parts are hard to find.
Installing a Phaserunner seemed the only option.

Power increase? Yes, depends on the battery. Currently it's only 52V 40A translating in ± 2000W
I'm planning a bigger 72V 50A battery for some more power.

Smoothness? The original Ultra is very smooth.
The Phaserunner / CA combo ... not so much.
I'm still struggling dialing it in. The Cycle analyst has so many settings.
At the moment there is a big judder/backlash in the drivetrain when taking off.
It's also quite hard to keep it at a constant speed.

[calfeetwenty]

What was the conclusion of installing the phaserunner? Does it help smoothness upon signal or
increase power? Just curious. BTW, beautiful build and great ideas!

Smoothness? The original Ultra is very smooth.
The Phaserunner / CA combo ... not so much.
I'm still struggling dialing it in. The Cycle analyst has so many settings.
At the moment there is a big judder/backlash in the drivetrain when taking off.
It's also quite hard to keep it at a constant speed.

I found your comment about the big judder when taking off very interesting. I built a TDCM Phaserunner KMX trike and I get just a hint of a noise/judder on take off. I have direct drive and you are geared. I wonder if the gearing is increasing the judder. I am seeing the same amp draw as you with my 52 volt system.

[Daxxie]

I found your comment about the big judder when taking off very interesting. I built a TDCM Phaserunner KMX trike and I get just a hint of a noise/judder on take off. I have direct drive and you are geared. I wonder if the gearing is increasing the judder. I am seeing the same amp draw as you with my 52 volt system.

I'm sure the slack in the drivetrain will increase the judder.
I didn't know that some Direct drives also suffer from this issue...
Must be the way the Phaserunner starts up the motor.
Hopefully they can smooth it out one day.

[Daxxie]

The judder problem has been keeping me busy for a while.

I read a thread of someone with a BBSHD/Phaserunner describing exactly the same problem.

My only remaining issue is that I experience a motor judder whenever I coast on no throttle and reapply throttle, such as coming out of rolling through a corner or coasting down a hill. I've read that this is not exactly easy to fix.
Can anyone point me in the direction of useful material for fixing/reducing this judder issue?
If I solve this, the bike will be basically perfect.

Here is a video I made of the problem. (It also shows you how flexible a Titanium frame is )


I tried all kind of settings.
Best result I got was with :

CA:
"Throttle Out Setting" of 4.00 V/Sec on The "ramp up rate"

and

Phaserunner:

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I also Tie wrapped the casette to the spokes to take the slack out of the freehub.

This didn't cure the problem completely but it made the bike at least driveable.

Then today I read this:

I think I have mostly solved the issue by Justin's suggestion in another thread. Basically, I put the bike on a stand with the rear wheel off the ground and raised the min throttle voltage in 0.01 V increments until the motor started turning (1.16V for me). That value provides very little torque, such that the bike will not move when the tire is contacting the ground, but it keeps the motor engaged. This morning on my commute to work it seemed to eliminate the issue I was having and it only increased the no load power consumption by about 3 W - totally reasonable. The only thing that is annoying is you can hear a high pitch (just barely audible) whenever the bike is powered up.

And gave it a try. (1.15V did it)
The judder seems completely gone!
Unbelievable.

[tolbert]

what pedals are those?

[Daxxie]

what pedals are those?

Got them from Ali.

https://www.aliexpress.com/item/TiTo-Ul ... 85445.html

[r3volution]

Fantastic build, that will take you anywhere.
Love the attention to detail.
My ‘Fatitty’ is identical with the exception of a 16S battery and nothing with a Luna badge

[tolbert]

thanks for the quick reply.

i have two bbs02's in the garage...looking to upgrade...love your build.

do you like the ultra now? what speeds you getting? range?

total price?

[msisko007]

Great job ,
I’ve just completed my first build and I’m planning my second build now. You’ve given me a few things to think about.

[El_Topo]

I wonder why this hasn't gotten more replies as this is such a great and clean looking build! Thanks for sharing as this is pretty much what I am aiming for except I need a frame with a narrower q-factor.

May I ask a few questions about the frame?

• How long are those chain stays?
• If you don't mind could you repost the first image (bike geometry) in your opening post again in higher resolution?
• Is there anything you would change about the frame if you could start from scratch, would you for example stiffen up any part of the frame given the high torque motor?
• What is the total weight of the bike with the battery and motor (48V 14Ah?), around 23 Kg?

I would love to hear more about your thought process on this build, if you don't mind just write down whatever comes to your mind or that you deem important.

Thanks in advance!