Bafang torque sensor + CAV3

E-HP

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I did some searching and have found a couple of posts mentioning a Bafang torque sensing bottom bracket and the Cycle Analyst, but not any where the two are used together.

I see one listed on Craigslist cheap enough to buy it to experiment with. Since I do a lot of stop and go while riding, this could contribute to my ultimate laziness, so I don't need to blip the throttle when starting off at an intersection. :wink:

I believe it may be this unit:
https://bafang-e.com/en/oem-area/components/component/sensor/sr-pa21132stc/
 
If it has an analog voltage out for the torque sensor, and a "standard" pulse output for the cadence sensor, there's no reason I can think of that it can't be used like any other BB torque/pas sensor. I think I posted in at least one thread about them around here with some details, but don't have a link.

If you don't want to use the cadence part, then as long as it has an analog voltage output from the torque sensor that goes from a low voltage up to a higher one, but is entirely within the 0-5v range, you could even just use that on the throttle input of the CA and not use it's PAS input at all, using the torque sensor as the throttle, and set teh CA's ThI range to match the sensor's range, and the ThO range to match your controller's input range.

In the latter use case, you might want to add a switch to the system that either activates the CA's brake input, or disconnects the TS from the CA's ThI pin, so that it can't send the bike going wild when you aren't actually riding it but you've turned it on. ;)
 
amberwolf said:
If it has an analog voltage out for the torque sensor, and a "standard" pulse output for the cadence sensor, there's no reason I can think of that it can't be used like any other BB torque/pas sensor. I think I posted in at least one thread about them around here with some details, but don't have a link.

If you don't want to use the cadence part, then as long as it has an analog voltage output from the torque sensor that goes from a low voltage up to a higher one, but is entirely within the 0-5v range, you could even just use that on the throttle input of the CA and not use it's PAS input at all, using the torque sensor as the throttle, and set teh CA's ThI range to match the sensor's range, and the ThO range to match your controller's input range.

In the latter use case, you might want to add a switch to the system that either activates the CA's brake input, or disconnects the TS from the CA's ThI pin, so that it can't send the bike going wild when you aren't actually riding it but you've turned it on. ;)

Thanks. I may take the chance. Next question though, is there a way to test it before installing it on the bike? Specifically, can I hook it up to test, before I start drilling a hole in the frame?
 
The test to be done depends on how it works. If it detects torque across the crank spindle you'd need to setup a test that applies torque that way, holding one end static and twisting the other relative to it. If it detects torque against the shaft you'd have to put a load on it like the chain does; it might only take holding the housing in a tube and pulling perpendicularly against the spindle end. The cadence sensor should output whatever pulse train it's designed to regardless of torque loading.

If all you need is a power-on test, that's as simple as wiring it up to the CA (or even just a power supply and voltmeter), and making sure it outputs the zero-torque-condition voltage expected, and that the cadence sensor pulses occur as specified during spindle rotation.
 
E-HP said:
I believe it may be this unit:
https://bafang-e.com/en/oem-area/compon ... a21132stc/
I've analyzed that sensor in detail:
index.php

https://www.pedelecforum.de/forum/index.php?threads/funktionsprinzip-bafang-drehmomentsensor.56636/

I would buy an ERider T9 or T15, that's the better choice, I think.

regards
stancecoke
 
https://www.ebay.com/itm/393292061715?hash=item5b92089c13:g:FhYAAOSw6r9g3Gsq

This ones 37$. ^^^^^ I think it has a 5v output. But it has that weird spider anchor that needs a specific chainring BCD mount. From the pics. Dont quote me. So you would have to buy the chainring spider too? ... I am looking for one too. I have been researching these cheepies.

ThIS one ( THUN) is also relatively cheap. https://www.ebay.com/itm/185182586819 Plus it is square taper on both sides. No fanch smanchy chainring spider needed. However, I think it is 5v too and the CA that I had with my last TSBB was 10v output. Can the CA3 do a 5v Tq sensor output? Work with it? I think so, but I have not done it yet.


I dont want to pay 125$ for a BB.

I am also looking for a bottom bracket that fits a 72mm and has a 150mm ( or so ) long axle. If anyone knows of one.. Let me know. Ty .
 
DogDipstick said:
https://www.ebay.com/itm/393292061715?hash=item5b92089c13:g:FhYAAOSw6r9g3Gsq

This ones 37$. ^^^^^ I think it has a 5v output. But it has that weird spider anchor that needs a specific chainring BCD mount. From the pics. Dont quote me. So you would have to buy the chainring spider too? ... I am looking for one too. I have been researching these cheepies.

Looks like the one I see on Craigslist. $29, but I'll need to check out the chainring thing. Thanks.
 
DogDipstick said:
I dont want to pay 125$ for a BB.
Normally the Bafang (including the spider :wink:) is much more expensive than the ERider. Good luck with sourcing the spider wherever :shock:

DogDipstick said:
ThIS one ( THUN) is also relatively cheap
This Thun is just a PAS, no torque output. The thun torque sensor is labeled with RT
https://thun.de/project/x-cell-rt-3-0suitable-for-pedelecs-and-e-bikes/

regards
stancecoke
 
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