BBSHD Controller Cover – Bafang Mid Drive Blanking Plate for ASI BAC Conversions

The BBSHD controller cover is a passive cover plate made for the Bafang BBSHD (BBS-HD) mid drive motor. It closes the empty bay left in the motor housing after the original factory controller is removed. Riders reach that point when they switch to an external ASI BAC controller. The plate simply seals the cavity, nothing more.

During a BBSHD conversion with an ASI BAC series controller, the stock controller is lifted out of the motor case. The controller then lives outside the motor, so an open aperture remains on the side of the housing. This cover closes that aperture. It carries no electronics at all, so there is nothing to wire in.

The part is shaped specifically for the BBSHD motor. BBSHD is a mid drive unit that mounts in the bicycle bottom bracket, so the housing contour is unique to that model. Because the cover follows that exact contour, no improvised patching is needed. It is aimed at e-bike conversion enthusiasts and workshops finishing an ASI BAC build.

Key Benefits

• Closes the open controller bay – after the factory controller comes out, an empty pocket remains in the motor housing, and this plate covers it.
• Built for ASI BAC conversions – the part exists for exactly one scenario, where the stock controller is replaced by an external ASI BAC unit.
• Matched to the Bafang BBSHD housing – the shape follows the BBSHD motor outline, so no improvised workaround is required.
• Keeps out dust and grit – a sealed aperture stops dirt and road spray from reaching the motor internals.
• Tidy finished look – the motor reads as complete after the conversion, with no visible hole in the side.
• Fully passive part – there are no circuits, wires or connectors inside, therefore no connection work is involved.
• No change to motor behaviour – power output and control settings stay exactly as they were.
• Straightforward fitting – the cover mounts to the motor housing in the position of the former controller lid.

Who Is This For?

This cover is made for owners of the Bafang BBSHD (BBS-HD) mid drive motor. Above all, it suits riders who have already moved to an external ASI BAC controller, or who plan that swap soon. It is the finishing piece of that particular job.

ASI (Accelerated Systems Inc.) BAC series controllers mount outside the motor. That applies to the BAC800, BAC855, BAC2000 and BAC4000 alike. Because each of these lives externally, the factory controller has to leave the motor, and its bay is left empty. At that moment this plate becomes necessary.

Conversion enthusiasts and e-bike workshops are the main audience here. It also suits anyone upgrading a BBSHD drivetrain who wants the motor to stay closed and tidy. However, the part is not intended for BBS01 or BBS02 motors, since those housings are different.

Technical Specifications

Why Choose This Cover?

After an ASI BAC conversion, the Bafang BBSHD motor is left with an open cavity. That opening lets dust and mud travel straight into the motor internals. Covering it is therefore a practical decision, not only a cosmetic one.

This plate is made for the BBSHD housing rather than sold as a universal fix. As a result, there is no need to cut plastic, glue on patches or wrap the side in tape. The fit follows the housing, so the job stays clean.

In addition, the cover changes nothing about how the motor works. It adds no power and takes none away. It is a spare part that completes one specific stage of a conversion. Once the external ASI BAC controller is wired and mounted, this plate is the last step before you ride.

Frequently Asked Questions

Which motor does this cover fit?

• It fits the Bafang BBSHD (BBS-HD) mid drive electric bicycle motor.
• BBSHD is a mid drive unit installed in the bicycle bottom bracket.
• The shape follows the BBSHD motor housing contour.

Does it fit BBS01 or BBS02 motors?

• No, the part is not intended for BBS01 or BBS02.
• Those motors use different housings.
• Only the BBSHD housing is supported.

Which ASI BAC controllers is this relevant for?

• It suits builds using ASI BAC series controllers.
• That includes the BAC800, BAC855, BAC2000 and BAC4000.
• All of these mount outside the motor housing.

Does the cover contain any electronics?

• No, it is a fully passive part.
• There are no circuits, wires or connectors inside.
• Therefore no wiring or connection work is needed.

Will it affect motor power or settings?

• No, it has no influence on power output.
• Control settings and motor parameters stay unchanged.
• Its only job is covering the aperture.

Where does the cover mount?

• It mounts on the motor housing itself.
• The fixing point is the former controller compartment.
• It takes the place of the original controller lid.

Do I still need it if my bike is stored indoors?

• An open aperture still admits dust and dirt while riding.
• Sealing the cavity protects the motor internals.
• It also gives the converted motor a finished appearance.

For anyone running a Bafang BBSHD with an external ASI BAC controller, this cover closes the last remaining gap in the build. It seals the housing, keeps grit away from the internals and leaves the motor looking complete. No wiring, no cutting, no compromise on motor behaviour.