Smartmotion Pacer power loss and DIY fix.

ian fisher

New 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.
 

ian fisher

New Member
been for a decent test ride today 54klm including 3 hill climbs, one climb of 5klm, Iv'e only ever used the torque mode and on the lowest power setting for hill climbs and it worked perfect today on level 1 and level 2 but still a slight hesitation on level 3 or above. The cadence mode still works perfect in all power settings. Using level 1 across town in torque mode the bike worked perfect and maintained an even 25kph, and on the hill climbs 10kph with no hesitation.
Anyone with a Smartmotion Pacer should check the way in which the bottom bracket cable is routed whether or not you have power loss issues, simply turn the bike upside down and see where the cable exits the bottom bracket, and where it enters the frame, if it is pinched underneath the gear shift cable against the frame then it's easy to re-route, you don't need to remove the cranks or bottom bracket. Using a flat blade screw driver carefully prise the LED light out of the frame, it pops out fairly easily, then find the connector on the bottom bracket cable, disconnect it and have a close look at this cable for chaffing, if it is not damaged then simply re-route the cable so it sits above the gear shift cable.
The Pacer is basically a great bike but not without some faults which so far have been easy to fix.
I had a previous power loss issue that I discovered was due to the battery shaking slightly loose and repaired this by making a steel collar that fits into the recess on the battery where the locking pin locates, the battery is secure tight now and cannot shake loose at all. I see a lot of people posting on this forum with power loss/motor cut out issues and I think that battery fitting is the first thing to check, if you can move the battery while it is locked in position, this could happen while you are riding and any slight disconnection could cause a power loss.
 

Robb

New 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.
Seems that Smartmotion are having a lot of problems with the Torque sensor
 

ian fisher

New Member
update: all is well with the pacer/diy fix, torque sensor still working well on the lowest two power settings, it will slightly hesitate on higher settings, however, I have discovered that if I set off first in cadence mode and increase the power to the highest level before switching to torque mode, it rides fine with no hesitation.
I have found a local Smartmotion dealer who can supply a replacement bottom bracket but I'm not going to do that unless the one that I fixed actually fails completely .
Since my last post in April 2020, I have added another 800klm on the odometer, fitted a shorter handlebar stem for a less stretched out, more upright riding position, and fitted two new narrower tyres, 175's instead of 2.0 and I regularly use the bike to commute around town.
the pacer is basically a good ebike with nice features .