Cube / Bosch - Speedometer started fluctuating but now reads zero

[winelight]

I have a Cube Touring Hybrid Pro 500 and last time I went out on it, the speedometer would occasionally, but with increasing frequency, start fluctuating wildly (both above and below the actual speed).

I took it to the bike shop today (it's under a year old) and they flashed it with the latest firmware, so I took it out to road test it, and the speedometer fluctuated again before finally giving up and reading zero.

The magnet / sensor were still correctly aligned (and there's a lot of tolerance anyway).

They're going to try changing the sensor (which I believe to be a hall effect type) and I'll report back when I hear any more from them.

To be honest a faulty sensor would surprise me. Yes I know they can fail, I had to change one on my car, but that was after 15 years and 100k miles, and the car engine goes round a lot faster than my legs do!

Just thought this might be of use / interest. And maybe someone else has had similar experiences they can share.

 

[winelight]

Just for the record, changing the speed sensor has indeed fixed it.

 

[Nev]

I had exactly the same problem when I first bought my e-mtb, Cube/Bosch combo like yours. Problem started in the first week or two of ownership. The sensor was changed, problem sorted, this was around 2 years ago, I've since done nearly 6000 miles on this bike and the problem never came back.

 

[David John]

I've been having the same problems just recently and my trip is under reading. Just a quick question.... does the motor still work if the display reads zero/speed sensor failure as I use it everyday for work.

 

[winelight]

If the sensor is not working, and so the display reads zero, then the motor will not work (as far as I know?). I think it needs to detect speed, as well as the torque that you apply (as measured within the bottom bracket).

If the sensor has gone flaky then in my experience, at any rate, it could fail completely at any moment.

 

[Nev]

If the sensor is not working, and so the display reads zero, then the motor will not work (as far as I know?). I think it needs to detect speed, as well as the torque that you apply (as measured within the bottom bracket).

If the sensor has gone flaky then in my experience, at any rate, it could fail completely at any moment.

Yes I agree with all this, that was my experience as well.

 

[David John]

If the sensor is not working, and so the display reads zero, then the motor will not work (as far as I know?). I think it needs to detect speed, as well as the torque that you apply (as measured within the bottom bracket).

If the sensor has gone flaky then in my experience, at any rate, it could fail completely at any moment.

Thankyou for your advice, i'll get hold of the bike shop and book it in asap. Thanks again