Bosch gen 3 performance, strange issue, torque sensor?

Nisse

New Member
Region
Europe
I have a strange issue with 2 bikes, both with Gen 3 performance motors. Both be running some 2k kilometres.
The torque sensor is hyper sensitive, have a look at the video (in the attached zip)
Any ideas on what can be the reason?
 

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if the wheel is not rotating when you do it does the cranks still spin? just want to make sure its not the drivetrain. you could take off the chain too and see if it does it. hope its not the torque sensor as that would mean a new motor.
 
if the wheel is not rotating when you do it does the cranks still spin? just want to make sure its not the drivetrain. you could take off the chain too and see if it does it. hope its not the torque sensor as that would mean a new motor.
Wheel rotates, its just behaving as an thumb gas. The motor drives the cranks with full force, pretty scary first time it occurred.
 
Its out of warranty so i guess its a new motor from ebay then. Bit disturbing that my other bike with same type of motor start to act the same.
Never had these issues with other e-bikes so start to wonder if the gen3 performance is flawed.
 
"I have a strange issue with 2 bikes, both with Gen 3 performance motors. Both be running some 2k kilometres.
The torque sensor is hyper sensitive, have a look at the video
Any ideas on what can be the reason?"
YES i could but the video is gone
"Wheel rotates, its just behaving as an thumb gas. The motor drives the cranks with full force, pretty scary first time it occurred." yeah it works.

OK then it's not the motor - right NISSE ? because the motor runs so remove that from your logic.

It's the torque sensor - which is a rotating dynamic ( read 'static' ) strain gage and it's associated signal transmission mechanism and that must be fixed.
I do know how to do this repair but most individuals do not.

From what I can determine from reading on line there is no one knowledgeable, with proper time and motivation to investigate and repair even one of these
and then document it for posterity like : UTUBE How to fix your: CHINESE/TORQUE/SENSORS[aka strain gage calibrated for the steel BB axle cross section stress @ 59DEG F {sniff} for fun and profit.]
 
"I have a strange issue with 2 bikes, both with Gen 3 performance motors. Both be running some 2k kilometres.
The torque sensor is hyper sensitive, have a look at the video
Any ideas on what can be the reason?"
YES i could but the video is gone
"Wheel rotates, its just behaving as an thumb gas. The motor drives the cranks with full force, pretty scary first time it occurred." yeah it works.

OK then it's not the motor - right NISSE ? because the motor runs so remove that from your logic.

It's the torque sensor - which is a rotating dynamic ( read 'static' ) strain gage and it's associated signal transmission mechanism and that must be fixed.
I do know how to do this repair but most individuals do not.

From what I can determine from reading on line there is no one knowledgeable, with proper time and motivation to investigate and repair even one of these
and then document it for posterity like : UTUBE How to fix your: CHINESE/TORQUE/SENSORS[aka strain gage calibrated for the steel BB axle cross section stress @ 59DEG F {sniff} for fun and profit.]
I added the video to an attached zip above
 
Are there Bosch E-Bike dealers/technicians where you live?
Yes, but as but as the motor more than 2 years old its out of warranty. Only to analyse will cost more than 100 USD.
I can get an new from ebay for +300USD. There no spare parts anywhere for the Bosch motors, only bearing kits
 
Yes, but as but as the motor more than 2 years old its out of warranty. Only to analyse will cost more than 100 USD.
I can get an new from ebay for +300USD. There no spare parts anywhere for the Bosch motors, only bearing kits
you could not replace the torque sensor anyway it is a extremely delicate and precise part.
 
Before replacing motor make sure its not faulty freehub causing back wheel to drive motor. Remove chain is best way to prove it.

Given you have 2 bikes doing same thing I'd approach shop you bought it from see what they come back with. A SW upgrade maybe all that is needed.
 
Before replacing motor make sure its not faulty freehub causing back wheel to drive motor. Remove chain is best way to prove it.

Given you have 2 bikes doing same thing I'd approach shop you bought it from see what they come back with. A SW upgrade maybe all that is needed.
Tested without chain and speed sensor unplugged, still same bug. The bosch system was updated last November
 
I have a strange issue with 2 bikes, both with Gen 3 performance motors. Both be running some 2k kilometres.
The torque sensor is hyper sensitive, have a look at the video (in the attached zip)
Any ideas on what can be the reason?
I couldn’t download your video so I am not clear on your problem.
Can I relate an oddity from my last Bosch Motor performance report?
(Performance Speed motor)

The report for the last 1,200 miles indicated the motor assist at all levels was only working for about 60% of total run time.

Given being known for my biking style of full speed Turbo all the time, neither my LBS Tech nor I could explain it. He even sent an investigative query to Bosch.

The answer became clear when I paid close attention to my cadence for the next few days.

I WAS COASTING 40+% OF THE TIME! I am worse than just lazy!

I had been riding near my Winter home in Arizona where the terrain is basically flat. And coasting a lot.
 
Some more input: normal functional motor has a "click" when stop peddling, some kind of freewheel clutch?
the malfunctional motor lacks it, could it be some mechanical failure?
Anyone have a service manual for Bosch motors?
 
The % coasting is close to equal for all assist levels.
Different gear, cadence and speed, along with assist level? If so, that's a different scenario to what I thought and is more complicated.

My comment was assuming all parameters remained the same, only assist level changed.

But then again if you're going the same speed, regardless of assist level, then there's equal opportunity to coast during a ride. Therefore my original comment would be incorrect!

This requires some experimentation.
 
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