electric bike spare parts

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When you decide to fit a conversion kit to your bike, it is inevitable at some stage in the future you will need to find replacement parts.  To make life easier I have compiled several product tables for e-bike parts and accessories for all the popular brands including Bafang and Tonsheng mid-drive motors as well as essential parts for most of the popular electric bike hub motor kits.

All the parts listed in this article come from reputable suppliers that I use regularly for my electric bike conversion business. They ship globally and you can expect delivery usually in 14-21 days (in some cases less).

E-Bike Spares, Parts and Accessories

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Electric bike components explained

Electric bike kits are composed of various different parts, all of which play an important role in the continued function of your e-bike. If you are new to the world of DIY electric bike conversions, it is always useful to know what roles these parts play (and where to buy them).

1. Electric bike controller

The electric bike controller is an essential part of the whole system and your e-bike will not function without it (it can be thought of as the brains of the system).  The controller has multiple functions including regulating the voltage and current as well as taking important data from pedals sensors, torque sensors, speed sensors and the handlebar display.

bafang bbs02b controller

A controller will also determine how fast your e-bike will be. For example, a 36v 15A controller when used in conjunction with a 36v battery will give you a maximum peak power output of 540 watts and a 48v30ah controller using a 48v battery (with 30A BMS) will give you a peak power output of 1440 watts. Note: the peak power output will be slightly higher on a fully-charged battery.

There are several reasons you may wish to change your controller. Sometimes the controller may just fail and need replacing, or you may want to increase the power output of your bike.

1500w electric bike controller

If you have purchased a 250w hub motor kit with a 36v 15A controller, you may feel you need more power to help you on the hills. A moderate increase in power can be achievable just by changing the controller. A 36v 22A controller would increase your nominal peak power to 792 watts.

If you decided to increase the power output, you would need to check the specification of your battery. Some cheaper batteries will only be able to handle a continuous current on 15A, so you would also need to upgrade your battery to one with a 25A BMS (battery management system).

48v 30ah triangle ebike battery

If you wanted even more power, a 48v 22A controller would give you a peak power output of 1056 watts. You would need to change your battery to a 48v with a 25A BMS.

One very important thing to remember is a 250w geared hub motor is designed to handle a finite amount of power and I would not recommend going to go too high with the power output as you would compromise reliability. The extra energy generated by a higher voltage / current controller will increase wear on the motor’s planetary gears.

2. Electric bike display

bafang 500c mini color display

An e-bike display will have a number of functions (depending on the model): Speed, power level, mileage, power output and even GPS navigation. There have been big improvements in recent years, notably full-colour displays and increased functionality. Bafang displays allow the user to choose up to 9 levels of pedal assist, which is great as you can gently increase the power available to suit your riding.

3. Pedal Assist Sensor

There are two different types of pedal sensors found on e-bikes: Cadence and torque sensing.

A cadence-based pedal sensor measures your pedalling rpm and gives you assistance as soon as pedalling starts. Most modern pedal sensors will ramp the power back once a high pedalling rpm is reached.

pedal assist sensor for ebike

On the Bafang mid-drive motor the pedal sensor is integrated into the motor unit. On a hub drive motor, the sensor would usually be a plastic disc with a ring on 5-12 magnets and a pick-up sensor.

The magnetic disc is usually mounted on the non-drive side on the square-tapered part between the crank arm and bottom bracket, with the pick-up sensor aligned with the disc and mounted less than 5mm from the magnets.

A torque-sensing pedal assist sensor is generally more intuitive and gives you assistance proportionate to the amount of force you are applying to the pedals. These types of pedal sensors are usually fitted to factory-produced electric bikes. Like the cadence-based pedal sensor, torque sensors usually reduce power at higher pedalling speeds.

a torque sensing bottom bracket for ebike

The Tongsheng TDZ2 mid-drive motor uses an integrated torque sensor and there are torque-sensing bottom brackets available for hub motors. These replace the bike’s existing bottom bracket and usually, a hole needs to be drilled in the bottom bracket shell (on the bike frame) for the sensor lead – this needs to be done carefully and a rubber grommet inserted into the hole as to prevent damage to the sensor lead.

4. Speed Sensor

Certain motors require an external speed sensor – primarily the Bafang and Tonsheng motors, but also some hub motor kits. The pedal assist will not work properly on the Bafang without a correctly installed speed sensor and will throw up an error code.

bafang speed sensor

A speed sensor is usually mounted on the chainstay and a small magnet is fitted to one of the spokes to align with the sensor.

The speed sensor has a couple of functions, one is to provide an accurate speed reading for the display and the other is to provide data to the controller for pedal assist.

5. Gearshift Sensor

bafang gear shift sensor

Not long after the Bafang mid-drive was released, it quickly became apparent that the extra power being transferred through the bike’s drive-train was causing premature wear to the chain, derailleur and gear cassette (particularly on the more powerful models).

The Bafang gearshift sensor was released soon after, and it works by threading the rear shifter cable through the hole in the sensor. When shifting through the gears it senses movement in the cable and briefly cuts the motor to enable smooth gear changes and thus prevent wear on the gear components.

Having a gear sensor is even more important if you have an internally geared rear hub like a Shimano Nexus or Alfine, as these hubs weren’t really designed to handle the torque of a BBS02 or BBSHD.

6. Throttle

Most e-bike kits come with throttles. There are different types of throttles available: The most common type is a thumb throttle. These are easy to fit on the handlebar and allow for the electric motor to be used independently if the pedal assist.

Throttles are very useful to get you going, especially if you have knee problems that make pedalling from a standstill difficult. They can also provide you with a break from pedalling if you get tired.

ebike twist throttle

It should be noted that it is unwise to use throttles on long, steep hills (unless your motor is very powerful) as the extra load can cause heat build-up and result in the controller or motor failure.

Other types of throttle available are twist and half-twist throttles the same as would be found on a motorcycle. These throttles work well but can interfere with gear shifters.

7. Brake cut-off sensors

These are nearly always provided with e-bike kits. They function as an auxiliary safety measure to cut power. Fitting these is a matter of personal preference. On torque sensing systems they are not necessary, but with more powerful motors that have a throttle control, it may be wise to have them fitted just in case the throttle sticks open.

There are different kinds of brake cut-offs. The types usually provided with kits are simply brake levers with a simple switch and a lead coming off the lever that plugs into the wiring loom (or directly into the controller). These kinds of brake sensors are only suitable for cable-operated brakes and would not work with hydraulic brakes.

hydraulic brakes for ebike

There are sensors available for hydraulic brakes, these work by sticking a magnet to the brake lever and aligning the sensor so that when the brakes are pulled in the magnet moves away from the sensor and cuts the motor out. In my experience, these kinds of sensors can be difficult to fit on certain brakes and are also prone to getting knocked out of alignment.

If you really feel you need the cut-off sensors, it would be worth buying a complete set of special hydraulic brakes with the sensors fitted. These will add to the cost of your build but will give you a much cleaner, more professional finished product.

8. Wiring Harness

bafang wiring harness

This is basically a wiring loom that connects various components, usually from the handlebar back to the controller.


Nearly all electric bike parts and accessories are manufactured in China, and if you are happy to wait a couple of weeks then there are great savings to be made buying directly from suppliers on Aliexpress.

I am an affiliate for Aliexpress and earn a small commission for referrals from my website, you will pay exactly the same price as if you visited their site directly and the commissions I receive help to support the upkeep of my website.

Bafang Parts

The table below contains all of the Bafang motor parts you will ever need. All the parts listed below come from reputable suppliers and are shipped globally to most countries.

Find and compare prices on Bafang motor parts and accessories

A lot of Bafang parts are also now available through eBay

Tongsheng Parts

The Tongsheng parts listed below all come from trusted suppliers with international shipping to nearly every country

Find and compare prices on Tongsheng motor parts and accessories

Visit eBay for more Tongsheng parts

General electric bike parts

Click on the link below for a selection of essential motor parts to fit most generic e-bike kits. These include upgraded controllers, colour displays, torque sensors and much more. Global shipping applies and all the sellers I have personally used myself.

Find and compare prices on general e-bike conversion kit parts and accessories

If you are after a particular part, leave a comment below and I will try and source it for you.

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    1. I have checked on Cycle Republic’s website and it looks like they have compatible chargers in stock. When did you buy the bike? If the charger has failed it should be covered by the 2-year warranty. Here is the link for the charger.

  1. I also wanted to add that I think even if there is no internal speed sensor on the TSDZ2, I think it’s not likely required (strictly speaking). The torque sensor determines whether the motor needs power, and AFAIK the speed sensor is only used to print the speed on the display. But if a rider has a satnav or doesn’t care about their speed, the speed sensor can probably be omitted.

    1. Hi Bob,

      I checked out that link you sent and it looks like a typo. The eBay listing it links to clearly shows the external speed sensor (which mounts to the chainstay). I think they’re getting their wires crossed. The only internal sensors on the TSDZ2 measure torque and pedalling cadence.

      You can use the TSDZ2 without the speed sensor, but you will not be able to set a maximum assisted speed limit (for legal requirements) or use the trip function on the display. I have tested them without the speed sensor fitted and it doesn’t appear to impact the pedal assist function as that primarily relies on torque and cadence sensing.

      I’m servicing a customer’s bike on Monday, so I will take the measurement of the TSDZ2 from the BB shell to the end of the shaft (chainring side) and post it here.


  2. Ronald Cashmore, It all sounds very good, I like it, especially the torque control, if I understand correctly one can also pedal normally with motor disengaged ? Could I use a Lekkie bling ring with this motor ?I am now 88 yrs old and begin to feel it; I live in a very hilly area, I am now 10 to 20 Km/hr slower than 20 years ago but speed is not important I am also mildly asthmatic, throughput max 440-480 ltr/min,not serious and until recently not a problem; I live in a very hilly area and don`t avoid the climbs, I still have the strength but during the last two years lung performance has steadily declined, I still climb the hill but on the big ones I have to stop for a one to two minute break, time is not important but it would be nice to keep rolling and a bit of assistance will keep me rolling longer, I would rather die on a bike than in bed.Thank you for a helpful review, from what you say it might be as well to buy the nylon reduction gear as a spare in hand.I am an amateur engineer with a well equipped shop, a manual is always helpful but I should be able to cope with installation and wear and tear problems.Thank you again, best wishes, Ronald Cashmore

    1. Hi Ronald,
      With the torque-sensing Tongsheng TSDZ2 motor, there is a slight increase in pedalling resistance with the motor switched off, but in my experience it isn’t as noticeable as on the Bafang. There is also a 104 BCD chainring adaptor available for this motor or you can purchase a small 34t chainring if required.

      Lekkie only seem to do chainrings for the Bafang BBS motor. Here is the link to the supplier I purchase most of my Tongsheng mid-drive motors from: http://s.click.aliexpress.com/e/balgbzT2 they also offer a duty-paid shipping option, which works out cheaper than paying duty your end.

      This company can also supply the 34t chainring option and all the spare parts you would require (nylon gear etc). The last kit I ordered from them took 5 working days to get to the UK.

      My battery supplier UnitPackPower usually have a good choice of batteries in stock in Germany, so delivery would be very quick.

      I will be posting an installation video on YouTube soon and will put it on my Tongsheng TSDZ review page.

      I share your passion for cycling. I ride about a 100 miles a week on average and can’t ever imagine being without my Dawes Galaxy touring bike.

      If you need any more help or advice, please let me know.

      All the best,

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