How to Open an E-Bike Hub Motor

Based on your budget, there are two primary e-bike motor types to consider when selecting an electric bicycle: mid-drive and hub motors. The former are installed into your bottom bracket while cranks of both types tie into them directly, whereas hub motors can be located either on either the front or rear wheel of your bicycle.

Hub motors operate independent from your pedaling system, so they can still provide assistance even if your chain or derailleur snag. Furthermore, hub motors tend to be cheaper than mid-drive motors.

 How to Open an E-Bike Hub Motor

Remove the Axle

Before attempting to remove the axle from your ebike hub motor, ensure the bike is in a stable and safe position with its chain shifted into its smallest cog. Once in position, turn off and disconnect its plug.

Unknowingly opening an ebike hub motor without first disconnecting power and sensor leads can result in irreparable damage to its components. Sensors and power leads distribute current to the motor, and any damage to either of them could render the whole system inoperable.

After disconnecting power and sensor leads, use a wrench to loosen axle nuts on either side of the frame using appropriate size wrenches - be careful as these nuts can become very tight once loosen. Once loosed they can be difficult to dismantle once removed.

Once an axle has been taken apart, carefully store it away in a safe location, taking care not to damage its brake rotor. Also ensure that its cutout lines up with frame dropouts; and when reassembling wheels make sure there are no creases in either tire or tube and ensure its notch for motor cable is facing forward.

Dependent upon the make and model of your ebike, depending on which parts are broken you may be able to contact the manufacturer directly for assistance with finding replacements parts. In addition, local shops or online ebike communities could help find axles suitable for your model of bike.

Remove the Cover

Step two is to remove the cover from an ebike hub motor, which may prove challenging due to being held by magnets and axle. To do this, a small screw driver should be used; start off small as this will avoid damaging wires inside of motor.

Once you have selected an appropriate screwdriver, remove the cassette lockring tool and all six bolts on the drive side of the motor. Cradle the cassette side of the motor while lightly tapping its non drive side axle using a mallet or hammer; this should help dislodge its stator motor allowing you to remove its cover.

Once the cover is off, it is recommended to test all sensors for continuity using a multimeter in order to ensure there are no breaks or damages in their leads.

 How to Open an E-Bike Hub Motor

Remove the Magnets

Once you've removed all of the screws and carefully peeled off the cover (which holds your motor in place against magnet forces), it's time to un-solder and dis-solder magnets. While not difficult, this process may prove tricky if your hands or grip are small or large enough. If having trouble dismantling magnets is difficult for you, use a thin flat steel bar wedged under them; I found this worked particularly well when working on both my Giant Trance E+ and Specialized Vado ebikes.

Once the magnets have been taken off, it is advisable to inspect the wiring inside for cuts, scrapes or missing insulation as this can have a dramatic impact on how easily or hard your hub motor turns.

Multimeters can also be used to test hall effect sensors. When doing so, I advise creating a firing order table using masking tape and felt-tipped pen in order to mark 46 points around your motor for easy matching of readings later.

With the phase wire leads (heavy winding wires) disconnected from each sensor, you can test each separately by comparing resistance (in ohms) between two sensor leads. If one stands out as having significantly higher resistance than the others, this may indicate it is shorted with another sensor.

Remove the Sensors

The controller relies on these sensors to distribute power to each phase winding, so if one fails, the entire system becomes inoperative.

There are various methods for checking sensor leads, but the easiest is using a multimeter to check each output from each sensor lead (small wires on either side). A good sensor should produce a fairly low voltage change while dead sensors have almost no output or may sputter; this should help identify which lead is problematic.

Another method for testing sensors is creating a firing order table on a spreadsheet and assigning each lead with their magnet pole number (1-46 for this motor). When the motor is powered on and at rest, use your multimeter to record each sensor's output while slowly turning the wheel - do this for all 46 leads (there will be 46 total).

Once you have the firing order table and tested the sensors, remove all cable ties from the sensor board and sensor leads. With your wire cutters, cut away at any remaining wire ties to free leads and sensor board. Inspect for damage or replace as necessary before soldering them together again once complete. Once everything has been assessed as working, reattach both sensor board and motor leads back onto your stator yoke for reuse.