How to Replace Damaged Hub Motor Cable on E-Bike

Replacing a damaged hub motor cable on an e-bike involves removing the wheel, opening up the hub motor, and installing a new cable through the axle with careful soldered connections. In essence, you’ll need to disassemble the motor to access the wires, feed a replacement harness through the axle, and reconnect all the correct wires. It’s a delicate fix that requires some electrical skills, but it can be done at home with patience.

In this blog, we’ll cover a step-by-step guide to do it safely, why these cables get damaged, what tools you need, and tips to prevent future cable issues.

Why E-bike Hub Motor Cables Get Damaged (Common Causes)

E-bike hub motor cables are the bundle of wires running from the motor, usually through the axle, to connect with the controller. This location makes them vulnerable. One common cause of damage is improper wheel handling during maintenance.

For example, a rider “went to fix a rear flat... [and the] red wire snapped” due to rough handling. The cable can get pinched or severed if the wheel isn’t carefully removed or if the axle is allowed to spin unexpectedly.

Another major cause is axle spin-out. If the axle isn’t secured tightly (or lacks a torque arm), the motor’s torque can make it twist in the dropout. This spinning yanks the cable and can rip wires right out.

Axle spin-out often results in severe damage to the frame or motor – the cable usually gets torn in the process as well. Using a torque arm (a steel bracket that braces the axle) is critical, especially on powerful motors, to prevent this (more on that in the Tips section).

Physical strain or accidents can damage the cable too. A hard fall or crash might crimp or cut the wires – in one case, “after a fall, the power cable was injured and the motor stopped turning”.

Even a bike shop or DIY repair can accidentally hurt the cable: one user reported his hub cable was crushed in a vise during a gear install. Over time, normal wear can also take a toll. The constant flexing and vibration at the point where the cable exits the axle can cause the insulation to rub off or wires to fray, especially if the cable isn’t well-secured or protected.

If you see any exposed wire or cuts in the cable, take it seriously – a partially severed cable can cause intermittent power loss, error codes, or even short out your controller.

Signs of cable damage include the motor stuttering or not running at all, especially if it happened suddenly after an event (like a wheel removal or impact). You might visibly see a sliced or pinched section of cable near the axle.

Some e-bikes will throw an error code on the display when a hall sensor wire is broken (for example, “hall sensor error” or fault code 03 on certain models). In general, if your hub motor was working fine until a recent incident and now won’t spin, inspect that cable first.

SEE ALSO Common E-bike Error Codes Explained and How to Fix Them

Tools and Preparation for Hub Motor Cable Replacement

Replacing a hub motor cable is a technical job, so gather the right tools and set aside ample time. Here’s what you’ll need and how to prepare:

Basic Bike Tools: Wrenches or hex keys to remove the wheel. Many rear hub nuts are 18mm, and you’ll also need a wrench or hex key for any torque arm or anti-rotation washers. If your motor has a freewheel/cassette on it, you may need a cassette lockring tool or freewheel puller and chain whip to remove it (geared hub motors often hide cable connections or screws under the gear cluster).

Screwdrivers/Torx Bits: To open the motor casing. Some hub motors use small hex screws or Torx screws on the side cover. Make sure you have the correct bit (e.g. T25 Torx, which is common on motor case screws).

Soldering Equipment: A good-quality soldering iron (ideally 40-60W or temperature-controlled) with a fine tip for electronics. You’ll be soldering tiny wires on a circuit board in the motor, so your “solder game needs to be on point”.

Get electronics solder (rosin-core) and possibly solder wick or a desolder pump if you need to remove old solder. Heat shrink tubing in assorted small sizes is essential for insulating the new connections (plus electrical tape as backup). A heat gun or lighter to shrink the tubing is also useful.

Replacement Cable Harness: Obtain a new cable that matches your old one. Most e-bikes use a 9-wire motor cable (3 thicker phase wires + 5 hall sensor wires + sometimes one extra like speed signal). It often has a waterproof connector.

You might get one from the manufacturer, but generic ones are available (one DIYer noted a “9-wire replacement cable available on Amazon for $12”). Ensure the connector has the same pin configuration as your original for plug-and-play. If you can’t find the exact cable, you may salvage one from a similar motor, or buy a generic and swap the connector by matching wires.

Misc. Tools: Wire cutters/strippers, a utility knife (to carefully cut back insulation), pliers, and possibly a small hammer or mallet. A digital multimeter is handy to test continuity on wires or verify hall sensor signals after repair. Have safety glasses and gloves as needed, especially when pulling apart the motor (there are strong magnets inside).

Workspace Prep: Work in a clear area with good lighting. You’ll be handling small screws and delicate parts, so a magnetic tray or small containers for screws is helpful. Keep a notebook or camera ready. It’s wise to take photos at each stage (before unplugging or unscrewing things) so you remember how to put it all back together.

Disconnect Power: Always disconnect the e-bike’s battery before any repair. Also, unplug the motor cable from the controller before removing the wheel. Typically, you’ll trace the cable from the hub to where it plugs into the bike’s wiring harness (often under the frame or near the controller box) and disconnect it there. This prevents any chance of a short and also frees the wheel for removal.

Finally, mental preparation: This repair involves more fiddling than a typical bike fix. If you’ve never soldered wires before, practice on some spare wires or an old circuit board first. Have patience and allocate a few hours so you’re not rushed. If at any point it feels overwhelming, you can seek professional help, but if you follow the steps methodically, you’ll get through it!

Replacing the Damaged Hub Motor Cable: Step-by-Step Guide

Now to the main event – replacing that cable. The process can be broken down into several steps. It’s a mix of bike mechanic work (removing the wheel, opening the hub) and electronics work (soldering wires). Make sure you’ve read the prep section above and gathered everything you need. Let’s dive in:

Step 1: Remove the Wheel and Disconnect the Cable

Unplug the motor cable from the bike’s wiring first (if you haven’t already). As mentioned, find the connector between the motor cable and controller harness and unplug it. This often requires unscrewing or unclipping a waterproof connector. Take note of any alignment markers so you can reconnect correctly later.

Remove any zip-ties or clamps securing the cable along the frame or fork. You want the cable free from the bike so the wheel can come off without yanking the wire.

Loosen the axle nuts on the hub motor wheel. Use the appropriate wrench (e.g. 18mm for many hubs). If your bike has a quick-release skewer (less common on hub motors), open it. Support the wheel as you loosen the second nut; the wheel may drop out once released.

Detach any torque arms or washers: Many hub motors have anti-rotation washers or a torque arm plate on the axle. Note how these are oriented (take a photo). They prevent the axle from spinning in the dropouts, so it’s important to reinstall them the same way. Slide them off and set aside safely.

Slide the wheel out of the dropouts. Carefully drop the wheel free from the bike frame. If it’s a rear wheel, you might need to ease the chain off the sprocket. If there’s a disc brake, gently maneuver the brake rotor out from between the pads. Do not yank the wheel away by the cable – handle the wheel itself and keep the cable slack.

Remove freewheel/cassette (if needed): Examine the side of the hub where the cable enters. In many geared hub motors, the cable comes in on the side with the freewheel or disc. Often, the motor’s screws are under the freewheel/cassette, meaning you’ll need to remove those gears.

Use a proper cassette tool or freewheel remover to take it off so you can access the motor cover screws. (For direct-drive hubs, the screws might be exposed on the flat side of the hub, so this step isn’t necessary in that case.)

By the end of Step 1, you should have the wheel off the bike, with the motor cable completely free and disconnected from the controller. The next steps deal with opening the motor itself.

Step 2: Open the Hub Motor

Now it’s time to get inside the hub motor where the cable is attached. Opening the motor can vary by model, but generally one side of the hub shell will come off:

Identify the side to open: Usually, the cable side cover is the one to remove (since the cable is attached to the internals on that side). If you removed a freewheel, that’s likely the side to open. The cover is typically held by a series of small bolts around the perimeter.

Remove the cover screws: Use the correct screwdriver or bit (often hex or Torx) to undo all the screws securing the hub cover. Keep them safe in a container.

Break the seal: Even with screws out, the cover might be stuck due to a press-fit or sealant (and the grip of the internal magnets). If the cover has threaded removal holes or if you fabricated a tool as in some guides, use that.

Otherwise, you can gently tap around the cover’s edge with a rubber mallet to start it moving. In one repair, the DIYer milled a custom tool that bolted to the cover and allowed him to twist it off with some hammer taps.

Most of us won’t mill a tool, but the principle is to apply even force to rotate or pull the cover. Be patient and do not pry with a screwdriver (you could warp the mating surfaces or let metal bits into the motor).

Pull the cover and motor core apart: Once the cover is loosened, you may need to pull the entire motor stator out from the hub shell. The motor consists of a stator (the electromagnet coil assembly attached to the axle) and a rotor (the ring with magnets attached to the wheel hub). Often the stator will stick inside the rotor because of the magnets.

Grip the axle (or use the axle itself in a vise with padding) and pull the cover or rotor shell upward evenly. Be prepared for a sudden release when the stator comes out – it’s a bit heavy. When done, you should have the motor internals exposed: one half is the ring of magnets (still inside the wheel), the other half is the coil assembly attached to the axle you removed.

Locate the cable connections: With the motor open, look on the inside of the cover you removed or on the stator for where the cable’s wires are attached. Typically, you’ll see three thick wires (phase wires) soldered either directly to the copper winding ends or to terminals, and five thin wires (hall sensor wires) going to a small circuit board (hall sensor board) inside the motor. The cable may be held in place by a strain relief or glued where it exits the axle – note that as well.

Optional - clean and inspect: Before proceeding to remove the cable, take a moment to inspect the motor internals. If you see any dirt, debris, or rust, now’s the time to clean. Wipe out any metal shavings (the magnets attract them), and check bearings for smoothness. Minor surface rust on the cover or steel parts can be gently scrubbed off.

Everything open and clean? Great – next you’ll actually remove the damaged cable and put in the new one.

Step 3: Remove the Old Cable and Feed in the New Cable

This step is the heart of the repair. Take your time and document wire colors carefully.

Label or photograph wiring: Before disconnecting anything, make sure you know which wire is which. The phase wires are usually colored (yellow, green, blue) and the hall wires are often red, black, blue, green, yellow (with red = +5V, black = ground, and the others signal wires).

Still, colors should match one-to-one with the new cable, but double-check. Snap a photo of how the wires connect to the hall board and coils. If the replacement cable’s colors differ, you may need to match function (pinouts) rather than color, so having a reference is important.

Desolder or cut the wires: There are two approaches here:

Full replacement: For a clean repair, desolder all the old wires from the motor. That means heating each solder point on the hall sensor board to free the tiny wire, and desoldering the thick phase wires from the coils or terminals.

This can be tricky due to space constraints, but it avoids adding extra splices. If you go this route, once unsoldered, skip to the next bullet about removing the cable from the axle.

Internal splicing: Alternatively, you can cut the cable a few inches from where it connects, and splice the new cable’s wires to those stubs. This was done in some guides to avoid disturbing fragile connections on the hall board.

If you choose this method, stagger the cut points (don’t cut all wires at the exact same distance from the board – cut some a bit shorter/longer) so that when you splice, the solder joints are offset rather than bunched together. This staggering, followed by insulating each joint with heat shrink, prevents one big bulge of solder joints that could rub on the motor casing.

Remove the old cable from the axle: Once the wires are free (either cut or desoldered), you should be able to pull the old cable out from the axle channel. Sometimes there’s a rubber grommet or silicone sealing the exit – peel or pry that out gently. Take note how it was seated; you’ll want to reseal the new cable similarly to keep water out.

Prepare the new cable: If your replacement cable has connectors on both ends, cut off the motor-side connector (you can’t feed a bulky connector through the narrow axle). Strip the wires on the new cable end to expose about 1/4 inch of copper on each.

If the new cable came with one end open and the other pre-terminated, even better (feed the open end through). Twist and tin the exposed leads with solder for easier connection later.

Feed the new cable through the axle: This can be fiddly. Push the new cable through the axle hole from the outside towards the inside (motor side). If space is tight, feed one wire at a time or twist them together tightly.

In some motors, the axle hole has sharp edges – avoid scraping the wire insulation. It may help to put a bit of lubricant (like a drop of light oil) on the cable to wiggle it through, or use a pull-wire technique (attach a thin string to the old cable before pulling it out, then use it to pull the new cable through the same path). Feed enough length so that the new cable reaches all the connection points inside the motor comfortably, plus a little slack.

Solder the new connections: Now connect each new wire to the appropriate point:

If you went the full replacement/desolder route: Solder each wire from the new cable to the motor where the old one was attached. That means soldering the three phase leads to wherever the originals were (often they are soldered to the thick phase windings or a pad – make sure to get a strong joint because these carry high current), and solder the hall wires onto the hall circuit board pads (tiny work – use a fine tip and don’t overheat the board).

Match each color exactly to the corresponding pad/lead it came from. If colors differ, use your photo/notes to match functions. Take care that no stray strands of wire are left touching anything they shouldn’t – a short here will kill the motor or controller.

If you chose the internal splice method: Solder each new wire to its corresponding old wire stub that you left. Remember how we staggered the cut lengths – now solder the pairs one by one. A trick is to slide a small piece of heat shrink tube onto one wire before soldering each pair, so after soldering you can slide the tubing over the joint and shrink it.

Make sure each splice is fully insulated. Do not leave any bare solder joint exposed. It’s wise to also wrap the entire bundle of splices with a larger heat shrink or tape once done, for extra insulation and strain relief.

In either approach, insulation is key. Hub motors have very tight clearances inside; any exposed metal could touch the motor casing (which is metal) and short out. As one repair expert noted, a lack of protection on the wires can “short circuit everything” if the cable rubs the housing.

So double-check your work – all connections covered with heat-shrink or quality electrical tape, and the bundle of wires arranged neatly, not crossing any sharp edges.

Secure the cable: Re-install any strain relief. For example, if the original cable had a rubber sleeve or was potted in silicone at the axle exit, do the same for the new one. You can use a bit of silicone or hot glue to fill the axle hole around the cable (after soldering) to prevent water ingress and give the cable some support. Ensure the cable’s external part has a gentle curve and isn’t kinked sharply at the exit.

At this point, your new cable is attached inside the motor! The hard part is over. Now it’s time to put the motor back together and test.

Step 4: Reassemble the Motor and Wheel

Reassemble the motor cover: Carefully place the motor stator back into the hub shell (or align the cover back onto the rotor ring, depending on how your motor comes apart). Mind the magnets – they will try to slam the parts together when they get close.

Keep fingers clear and guide the pieces together slowly. Make sure none of the internal wires are getting pinched by the cover; push them neatly into any grooves or channels they originally sat in.

If your motor had a specific alignment mark (some have marks so that the cover goes back in the same orientation), align that. Grease the cover’s threads or edge if it was threaded on, to make future removal easier.

Tighten the cover screws: Replace all the side cover screws you removed and tighten them evenly in a star pattern (opposite sides) so the cover seats flat. If you have some medium-strength threadlocker (Loctite Blue), you can put a tiny drop on each screw to prevent them vibrating loose. Do not over-tighten and strip them – snug is usually enough, especially with Loctite.

Reinstall freewheel/cassette (if you removed it): Grease the threads on the motor axle and thread the freewheel back on (or slide the cassette and tighten its lockring with a chain whip). Make sure it’s fully seated and the lockring or freewheel is secure. Also reattach any disk brake rotor if you had to remove one.

Put the wheel back on the bike: Lift the wheel and line up the axle with the dropouts. Be cautious with the new cable – keep it from snagging. For rear wheels, loop the chain onto the sprocket. Slide the axle fully into the dropouts on both sides.

If you have anti-rotation washers or torque arms, reinstall them in the exact orientation they were before. These typically have a tab that fits into the dropout or a certain direction – refer to that photo you took to get it right. A misaligned torque washer can lead to axle spin, which we definitely want to avoid now that you have a fresh cable!

Tighten the axle nuts: Once everything is seated, tighten the axle nuts firmly to the manufacturer’s spec (if known) or good and tight if not. Do not overtighten to the point of stripping threads, but the wheel should be very secure. If your bike has a quick release, close it tightly and ensure the wheel can’t wobble.

Reconnect the motor cable externally: Plug the new cable’s connector back into the controller harness. Align any arrows or keys on the connector and push until fully seated. If there was a locking sleeve, screw or slide that in place.

A partial connection can cause a hall sensor error or phase wire arcing, so make sure it’s secure. Use new zip ties to strap the cable back along the frame as it was originally, leaving a bit of slack near the axle for movement.

Test the motor: Before taking the bike off the stand or flipping it upright, test the system. Reconnect the battery, turn on the bike, and gently apply throttle or pedal-assist while the wheel is off the ground. The wheel should spin up smoothly. Listen for any weird rubbing or grinding – if you hear that, stop and inspect in case a wire is touching inside.

If the motor doesn’t run or stutters, double-check your connections: are all hall sensor wires connected properly? (A single hall wire miswired or not connected can cause the motor to not spin). If it runs, great! Also test the brake cutoff and any other motor-related functions to ensure everything behaves normally.

Final touches: Flip the bike upright, do a short slow ride test. Keep an eye on that new cable – it should stay put, not moving around or stretching. After a brief test ride, double-check the axle nuts tightness again (sometimes they settle). Now you’ve successfully replaced the hub motor cable!

Replacing a hub cable is not an easy feat – even experienced tinkerers find it challenging. If your repair was successful, give yourself a pat on the back. You’ve likely saved a significant amount of money and downtime by doing it yourself, and your e-bike is back on the road!

SEE ALSO E-Bike Motor Winding Failure Troubleshooting Guide

Tips to Prevent Future Hub Motor Cable Damage

After going through all that work, you’ll want to avoid ever having to do it again. Hub motor cables often get damaged due to stress and mishandling, so here are some tips to extend their life:

Use Torque Arms

As mentioned earlier, axle spin-out is a cable killer. A torque arm is a metal bracket that secures the axle to the frame, absorbing the motor’s torque. Especially if you have an alloy frame or a motor above 500W, install a good torque arm on the hub motor. It will prevent the axle from twisting and shearing off the cable in high-power situations. Think of it as cheap insurance for your bike’s motor and your safety.

Secure and Protect the Cable

Ensure the cable is fastened to the frame with clips or zip ties so it doesn’t flop around and snag on anything. At the exit of the axle, the cable should have a gentle loop and not be sharply bent or under tension.

You can add an extra protective sleeve (some use a piece of spiral wrap or an old thicker hose) around the cable at the axle exit to shield it from rubbing or abrasion. If your motor’s cable had a grommet or strain relief, always put that back in place properly.

A user on a forum lamented that his motor had “bad cable protection” by design – if that’s the case, you might have to improvise your own protection (like reinforcing the cable with an extra layer of heat shrink where it leaves the axle).

Be Careful During Wheel Removal

The majority of cable damage seems to happen when fixing flats or doing wheel maintenance. So when you remove your wheel, never let it dangle by the cable. Always disconnect the cable first and support the wheel.

When reinstalling, make sure the cable isn’t getting pinched in the dropout or twisted. Take your time – a rushed job in “bad weather” led one rider to nearly yank his cables apart and get an error afterwards.

Regular Inspection

Make a habit of checking the cable condition periodically. Look for any cuts, squashed sections, or exposed inner wires. If you spot damage early, you might prevent a breakdown.

For minor abrasion, you can apply liquid electrical tape or additional heat shrink as a preventative measure. Also ensure the connector between motor and controller is clean and tight – a loose connection can overheat and burn the plug or wires.

Avoid Water and Corrosion

Although many motor cables and connectors are waterproof, prolonged exposure can wick moisture inside. Try not to submerge the hub area. After wet rides, dry your bike and consider unplugging the connector to ensure no water sits inside. A bit of dielectric grease on the connector pins can help repel moisture.

Internally, if you ever open the motor and see water, dry it out and reseal openings. Rust inside the motor (like on the covers or magnets) can eventually rub wires and cause shorts, so keeping things dry will help your cable and motor live longer.

Lastly, realize that cables do undergo strain over thousands of miles. Some ebike owners proactively add a bit of slack or a loop in the motor cable to accommodate suspension travel or wheel movement.

The key is to minimize repeated bending at the same point. If your bike’s design causes the cable to bend sharply whenever the suspension compresses or the handlebar turns (for front hubs), reroute or adjust it so the bending radius is gentler.

By following these precautions, you dramatically reduce the chance of ever dealing with a broken hub motor cable again. Many experienced e-bikers and mechanics report that cable damage is a common issue they see almost daily, but with the right preventive steps, you don’t have to be one of those cases.

FAQs

How can I tell my hub motor cable is bad?

Look for cut or pinched insulation near the axle, sudden loss of power, or a “hall sensor” error on the display. Any exposed copper means the cable’s shot—replace it before riding.

Can I just splice the broken section instead of swapping the whole cable?

You can splice, but it’s less durable. A full-length replacement sealed with heat-shrink and silicone lasts far longer and keeps water out.

Where can I buy a replacement hub motor cable?

Check your e-bike brand first. If they don’t stock it, search online for a “9-pin e-bike motor cable” or “Higo/Julet 9-wire harness.” Match the connector style and wire count.

How much does a new hub motor cable cost?

Generic 9-wire cables run $10–$25 online. Add basic solder/heat-shrink supplies if you don’t already have them. Still way cheaper than a new wheel.

Do I need a torque arm after replacing the cable?

Yes—reinstall (or add) a torque arm. It stops the axle from twisting, which is the #1 reason motor cables rip out in the first place.