Bafang BBS02: Terry Symmetry Shift Sensor & Cable Guides

The Bafang BBS02 came with (because I added it to the order) what looks like a genuine shift (“gear”) sensor made by the original company in the Czech Republic:

Terry Bafang - shift sensor - installed
Terry Bafang – shift sensor – installed

On a typical bike, it mounts against a cable stop with the cable housing holding it in place against its other end:

Tour Easy Bafang BBS02 - shift sensor - installed
Tour Easy Bafang BBS02 – shift sensor – installed

The Terry Symmetry has only two lengths of housing: in front of the adjuster on the downtube and behind the stop brazed to the chainstay. In either position, the sensor would move as the shift cable flexed and (IMO) put unreasonable stress on the electrical cable running to the motor.

Yes, the Tour Easy has those same two lengths of housing, but the forward one joins a sheaf of wires & cables that barely moves.

Fortunately, the sensor fits neatly between stations 1 and 2 along the downtube, with a snippet of PTFE lIned housing holding it firmly in place, with the 3D printed battery mounting blocks including paths for both cables:

Terry - Bafang battery - all stations - solid model
Terry – Bafang battery – all stations – solid model

The shift cable originally ran from the adjuster in the front to the guide under the bottom bracket along a slightly diagonal path I could not possibly match. Instead, the path is now parallel to the downtube from the front adjuster:

Terry Bafang - OEM shift stop
Terry Bafang – OEM shift stop

.. to the rear block, where it angles downward over the motor to the bottom bracket:

Terry Bafang - shift cable clearance
Terry Bafang – shift cable clearance

The front block at station 1 has a Delrin / acetal bushing to align the cable with the rest of the blocks:

Terry shift guide - acetal installed
Terry shift guide – acetal installed

Yes, it’s a round peg jammed in a hexagonal hole:

Terry shift guide - acetal hole
Terry shift guide – acetal hole

Turning it from stock is well within the capabilities of Tiny Lathe™:

Terry shift guide - acetal cutoff
Terry shift guide – acetal cutoff

For great slippery, a similar UHMW PE bushing supports the cable bend at the rear of the station 4 block:

Terry shift guide - UHMWPE installed
Terry shift guide – UHMWPE installed

The Basement Laboratory Warehouse Wing disgorged an overly large rod taxing Tiny Lathe™ to its limit:

Terry shift guide - UHMWPE turning
Terry shift guide – UHMWPE turning

Memo to Self: next time, just saw off a stub and move on.

3 thoughts on “Bafang BBS02: Terry Symmetry Shift Sensor & Cable Guides

  1. I hope this isn’t one of those projects where you say, “You buy the parts and I’ll install them for you some afternoon.”

    1. I know myself better than that! [grin]

      The big question: would the battery fit anywhere on the downtube?

      After that, it was just pleasant problem-solving, solid modeling, and routine 3D printing, the kind of thing you can’t do when driven by either (or both) schedule or profit.

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