Carrera Subway Torque Sensing Bottom Bracket

[OldManToy]

Hey, I hope someone can help me with this.

I've the 2021 Subway 2.0 that has a torque sensor in the BB.

I came off my bike and bent the right side crank arm to had to change it. After my accident the motor worked fine and I could limp home.

After I changed the cranks I've had an odd experience with the motor mostly not kicking in. On one test it worked for 15 minutes, it was a bit jumpy but then it stopped and never worked after that. The head unit shows me battery power and speed (I've read it reads it from the hub) so I'm guessing those connections are all fine. I've checked the cable from the BB sensor to the controller and it's intact. Also its all clean and dry where the cables and controller are in the frame.

So, does anyone have any tips for other checks on the torque sensoring bottom bracket? Or any experience of how easily they fail?

I'd happily just buy a replacement BB but there aren't many and prices are quite high. It's part no EBBS20 T2. Also, does it have to be a like for like replacement or could I try the bafang equivalent? It seems to have the same six pin connector.

Anyway, tips and advice appreciated. I really can't face any faff taking it in to Halfords so really want to avoid that if possible.

Michael

 

[saneagle]

Pull the controller out of its compartment under the downtube and check the connectors. Also, check that you didn't damage the wires where they go through the BB. Any sideways movement would damage the cable if the crank took a bang. After that, you need to get it out and check the wires where they attach to it.

They're normally built strong, but the cables are easily damaged. Intermittent operation sounds like a bad connection rather than a U/S unit.

 

[OldManToy]

Thanks Saneagle.

I've done those checks of the controller and cables plus have carefully removed the BB but can only confirm it looks fine, ie no visible damage where the cable attaches to the unit. I couldn't see anything else to check. Is there?

The only cable near the BB is the one that attaches to it. The others drop out of a hole in the frame behind the controller bulge the pass externally under the BB. They all look fine.

One thing I found was that when I first reassembled ît I just did the BB cups up hand tight. That gave me odd intermittent power but only on the drag back of the pedal stroke. Next day I torqued it up properly to the 35Nm spec and got 15 mini of almost standard use but then it cut out and nothing after that.

So, I'm stumped!