ian fisher
Member
Smartmotion Pacer with intermittent power loss on torque sensor mode, Cadence sensor still worked fine.
Bike was purchased as used and is well out of warranty so I decided to look and see.
Removed both crank arms and turned the bike upside down then carefully prised out the LED light from the underside of the down tube, this exposes all internally routed cables and reveals a connector on the bottom bracket torque/cadence sensor cable.
The first thing I noticed was that the power cable from the bottom bracket was pinched under the gear shift cable tight against the bike frame.
I removed the left side bottom bracket cup and eased the bottom bracket out of the frame.
On close inspection the torque/cadence sensor cable was bent almost at a right angle, slightly damaged and a tiny bit of inner wire was exposed.
I straightened out the cable using thumb and finger and wrapped the cable with electrical tape then reassembled only this time I have inserted the gear shift cable into the frame recess first and routed the bottom bracket cable in a way that it is not obstructed by any of the other cabling.
Test ride went well and the torque sensor works perfect in the two lowest power settings but still just a slight hesitation on level 3 or above, this would indicate to me that the torque sensor cable is possibly damaged and maybe even a strand or two of wire is broken.
I will persevere with the bike as is for now but during the winter months I will remove the bottom bracket again and open the torque/cadence cable outer sheathing then solder a joint.
I did also actually disassemble the bottom bracket just to have a look and see how the sensors work, it's very simple to remove a circlip then remove two sealed bearings and the bottom bracket axle comes out, a circular magnet is attached on the axle and two sensor pickups are sealed into the bottom bracket with a small circuit board. It would not be difficult to cut the seal and remove the circuit board and sensor pickups to test the circuit and repair if necessary.
Initially when this problem occurred I emailed Smartmotion and several Smartmotion dealers to enquire about the cost and availability of a replacement bottom bracket...no one ever replied so f**k em all, there's no rocket science in ebikes so I have no hesitation in pulling something apart, after all, everything was assembled in a factory it can definitely be disassembled and repaired.
Bike was purchased as used and is well out of warranty so I decided to look and see.
Removed both crank arms and turned the bike upside down then carefully prised out the LED light from the underside of the down tube, this exposes all internally routed cables and reveals a connector on the bottom bracket torque/cadence sensor cable.
The first thing I noticed was that the power cable from the bottom bracket was pinched under the gear shift cable tight against the bike frame.
I removed the left side bottom bracket cup and eased the bottom bracket out of the frame.
On close inspection the torque/cadence sensor cable was bent almost at a right angle, slightly damaged and a tiny bit of inner wire was exposed.
I straightened out the cable using thumb and finger and wrapped the cable with electrical tape then reassembled only this time I have inserted the gear shift cable into the frame recess first and routed the bottom bracket cable in a way that it is not obstructed by any of the other cabling.
Test ride went well and the torque sensor works perfect in the two lowest power settings but still just a slight hesitation on level 3 or above, this would indicate to me that the torque sensor cable is possibly damaged and maybe even a strand or two of wire is broken.
I will persevere with the bike as is for now but during the winter months I will remove the bottom bracket again and open the torque/cadence cable outer sheathing then solder a joint.
I did also actually disassemble the bottom bracket just to have a look and see how the sensors work, it's very simple to remove a circlip then remove two sealed bearings and the bottom bracket axle comes out, a circular magnet is attached on the axle and two sensor pickups are sealed into the bottom bracket with a small circuit board. It would not be difficult to cut the seal and remove the circuit board and sensor pickups to test the circuit and repair if necessary.
Initially when this problem occurred I emailed Smartmotion and several Smartmotion dealers to enquire about the cost and availability of a replacement bottom bracket...no one ever replied so f**k em all, there's no rocket science in ebikes so I have no hesitation in pulling something apart, after all, everything was assembled in a factory it can definitely be disassembled and repaired.
