New Generations of BB Torque Sensors (Bafang and Sempu)

notger

100 W
Joined
Mar 14, 2013
Messages
279
Hi,

I'd like to make people aware of two new BB - torque Senors witch look really interesting.

One is the "New Generation Sempu T4" measuring torque on both sides cause measuring the chainring-force.
HTB1wL8FexGYBuNjy0Fnq6x5lpXaG.jpg

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https://www.ebikes.ca/documents/Sempu_Sensor_Manual_2018.pdf
https://de.aliexpress.com/item/dual...32795184280.html?spm=a2g0s.9042311.0.0.NQeeH7

with following specs:
sempu.JPG

the other one the Bafang SR PA31.32.ST and other Versions of it.
Using the same mesuring method, but with different specs.
HTB1HUdoOVXXXXcTaXXXq6xXFXXXt.jpg

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http://www.bafang-e.com/en/components/component/sensor/sr-pa0112s.html
https://de.aliexpress.com/item/Hot-...-acde-ccf8482dd9ce,scm-url:1007.13339.90158.0
-----------
Specs.:
bafngt.JPG

the interesting thing on Bafang is the the
Input Voltage(DCV) 4.2 - 5
Output Voltage(DCV) 0.74 - 3.2

cause that ??could allow to use the Bafabg without potential Pre-Controller like CA in any throttle-input.
But it could also be that it is specially produced for bafang controllers and would make strange behaviour acting as throttle.


So my main Motivtion for this thread is, instead of buying and testing both by my own, and mayb finign out that one of them is trash, i ask you for potential experiences with those Sensors ???

greets
Notger
 
And now, ontop of that, another Motivation would be to create a custom mi-drive-freewheel-bb-torque-sensor for my several mid-drive options with freewheels.

This could look like this.:
FW+spacer.jpg


adding a.:
index.php


to this Spot (lets call it chainring-spider-mount).:
index.php


any ideas on that ??
 
I'd make an adapter with BSA threads, the adapter would attach to the torque sensing BB using the splined/bolted interface. All the hardware for flanged freewheels could then be re-used. Chainline may be skewed outboard but a custom offset spider is easy.

-dave
 
tangentdave said:
I'd make an adapter with BSA threads, the adapter would attach to the torque sensing BB using the splined/bolted interface. All the hardware for flanged freewheels could then be re-used. Chainline may be skewed outboard but a custom offset spider is easy.

-dave

exactly my idea, just not sure, if the 1,37" / 35,8mm thread would fit on the......
index.php


and another Problem could be that the Sqare tapered crank would not, or very tightly fit on the crank ??
Many coulds,....Probably goot to test it.

What do you think about the Bfang ? or any experiences ?
 
Does anyone know this multi-tooth standard that Bafang is using on its chainring-spiders ? (if it is any standard)

HTB1HUdoOVXXXXcTaXXXq6xXFXXXt.jpg
 
I bet the 1.37"x24 threads are the same diameter as the 5 bolt pattern, so the FW would have to stick out over the spindle and impede on the crank. Would need some minimum spindle stickout to give the FW room.
 
Lingbei, a manufacturer, is also listing a torque and speed sensing bottom bracket on their website: http://lingbeimotor.com/a/products/p1/7.html

Little information, and I don't see any output flange so I assume it is only single sided. Also it is only square taper, so I wouldn't personally be interested in fitting one to a mountainbike, but I thought I would add the information to this thread in case it is useful to someone.
 
That Bafang BB crank looks really promising with those input/output voltages. Since I have a Phaserunner that has programmable throttle levels I think I’m going to pick that up for my bike.
 
zro-1 said:
That Bafang BB crank looks really promising with those input/output voltages. Since I have a Phaserunner that has programmable throttle levels I think I’m going to pick that up for my bike.

It does, but not sure if its supported by the CA as pre-controller ?
Probably it has its own "intelligence" inside ?
 
notger said:
It does, but not sure if its supported by the CA as pre-controller ?
Probably it has its own "intelligence" inside ?

I don’t use a CycleAnalyst, just the Phaserunner by itself
 
I just ordered the Bafang BB it was $149 USD from the US/EN site. I’ll need to get a chainring and pedal arms now too...

EDIT: The model the EURONAU is selling uses the square-taper shaft, not the splined shaft as linked to above in the original post - just FYI.

EDIT 2: I figured I should add the specs for the square-taper version here as they are slightly different from the version linked above.

Specifications:
Type Torque Sensor. Speed Sensor
Signals (Pulses/Cycle) 32
Input Voltage(DCV) 4.5 -5.5 (slightly wider range than the other model)
Output Voltage(DCV) 0.74 -3.2
Resolution (mv/N.m) 35
Operation Temperature -25 - 45 ℃
Shaft Standard JIS
Weight (g) 650-780

Mounting Parameters:
BB Width(mm) 68, 100, 73, 84, 110, 120 (it look like Bafang makes this in different BB widths, though the one on AliExpress is only 68mm)
Mounting Position Bottom Bracket
Cable Length(mm), Connector Type 150 G6.4 / 950 G6.4

Tests & Certifications:
IP IP 65
Certifications EN 15194 / EN 14764 / ROHS
 
I really wish it was possible to buy direct from Bafang. They have 4 items on their site that I would buy today if they had direct sales. I haven't found the Bafang BB with ISIS shaft standard on AliExpress. The EURONAU BB is listed 3 times, but it's the same square-taper JIS BB. I personally think JIS is fine for hub-drive bikes. I could see the benefits of an ISIS BB in the case of a mid drive that is powering through the shared chainring.

I really like that these new BB's all use a torque sensor that reads torque from the chainring spider instead of through bending of the shaft. And the integrated PAS sensor is just an added benefit. I am really pumped to see how this works with the torque throttle of the Phaserunner.
 
The Bafang BB I ordered has shipped. As soon as I get it I'll post pics here. I'll probably end up documenting the instal and testing in my build thread, but I'll be sure to link that here for easier reference.
 
I am looking at this wondering if it would be compatible with the GNG. Any thoughts?
I would rather avoid a throttle if at all possible.


Thinking about it, I am more interested in the Luna/Cyclone 3000W unit; however, I expect that when it comes time to order I will return to the BBS02, like I had before.
 
Just got a Sempu T4. Although it looks like it has external bearings on the non-drive side , it doesn't (the drive side has an external bearing to make room for the sensor bit), which is ok, and it will allow us to machine some of the material away to make room for mid-drive motor mounting plates, and possibly a freewheel. The spider mount is too large to adapt to freewheel threads easily. So, I will probably be looking into modifying a freewheel to fit. It seems to work as advertised on the bench. I'll try to get it into a bike today.
Sempu T4.png
 
I got the Bafang/EURONAU bottom bracket today. I'm not sure I'm going to be able to make it work with the Phaserunner on the throttle connection. While the input and output voltages are correct to use as a throttle, this bottom bracket has 6 wires in the cable rather than just 3 as you'd find in a throttle.

Here's pics:
bb-1.jpg

bb-2.jpg

bb-3.jpg

I have a feeling this BB was designed to only work with specific controllers and isn't a universal component.
 
Probably 3 of the wires are for the torque signal (input +, common -, and analogue torque signal out), and the others are for the cadence signal.
Did the supplier not send you a connection diagram? If not, that's pretty slack! Contact them and ask for one.
 
Drum said:
Probably 3 of the wires are for the torque signal (input +, common -, and analogue torque signal out), and the others are for the cadence signal.
Did the supplier not send you a connection diagram? If not, that's pretty slack! Contact them and ask for one.

That's my suspicion as well regarding the wiring. I should have known that it would have the additional wires, but I was hoping it was something totally new since the input/output voltages matched a throttle.

No, the supplier didn't even include a packing slip. It was literally just the BB parts in a plastic bag that was put in a padded envelope. I've reached out to them and they said they'll provide a wiring diagram for me. We'll see...

EDIT: Update: they wrote back and said they couldn't get a wiring diagram. Totally useless reseller. I gave them a poor rating.
 
Really happy with the response and feel of the Sempu T4. So much better than the left-leg only Thun sensors with lower pole count. The main issue is the lack of freewheel which results in an occasional tug on the pedals with the inertia of the motor and gears slowing down. Also, it's nice to be able to back pedal without dragging the motor around.
SempuT4 installed.png
 
zro-1 said:
I got the Bafang/EURONAU bottom bracket today.

There are some new pictures of the Bafang sensor at the german pedelecforum. The sensor is used in some Kalkhoff and Raleigh ebikes obviously. The brand of the motor system is called "Groove go" by Derby-Cycle.
But the pinout of the six wires is still not known... :(

regards
stancecoke
 
Anyone know where to get the Sempu T4 model in different BB widths? From their website, they offer a version with for 100mm BB, so it will fit on fat bike frames with a 100mm BB. But I can't seem to find it anywhere.

http://www.sempu.net/newsshow.php?id=1
 
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