Part 3 of eBike Conversions For Beginners series

Continuing the series of eBike conversions for beginners, in this DIY guide we will be looking at converting your existing bike to an electric pedal assist or throttle-only bike using a rear wheel hub motor eBike conversion kit.

Completing an eBike conversion using a rear wheel hub kit can be completed in 5 relatively easy stages.

This is part 3 of eBike Conversions for Beginners. If you are a complete beginner to eBike conversions it is strongly advised that you read or at least skim Part 1 An introduction to eBike conversions as it covers topics such as safety considerations that you need to think about particularly regarding hub wheel motor conversions.

Tools Required

You will need a standard bike toolkit including torx bits for disc brakes, wrenches, spanners, flat and crosshead screwdrivers plus a crankarm extractor and pedal wrench.

Type of Rear Wheel Conversion Kit Required

Preparation and installation of hub wheel

Remove old rear wheel from your bicycle. From old wheel remove inner tube, rim tape, and disc brakes (if you’re going to be reusing)

  • Check and if necessary tighten the spokes on your new wheel.
  • If freewheel didn’t come attached to the new hub motor, install the freewheel – initially screw it on by hand, then use the chain tool to tighten it up.
  • Line the hub wheel with the rim tape – this helps to prevent punctures from the spokes.
  • Place the hub wheel into the tire.
  • Insert inner tube. TIP If you partially inflate the inner tube – this will prevent pinching when finally fitting the tire over the inner tube and ensures a tight fit.
  • Now fit the tire with your tire levers and pump it up.
  • If the new rear wheel hub motor has provided mounts for a disc brake rotor, remove the six screws and spacer/dummy plate, before screwing your disc brake to the new wheel.
    • Use the same screws that were provided in the hub. If you use longer screws you risk damaging the hub motor as they can catch inside the hub.
    • TIP From the first screw put in, the next screw should be opposite that screw. Continue like that till all 6 screws are in.  This ensures an even fit.
  • Assuming your bike is upside-down, make sure the entrance point where the cables protrude from the hub motor are facing upwards to prevent rain etc from entering when on the road.
  • Install the rear wheel on to the bike with round washers inside of the frame. Make sure wheel fits evenly within the brake caliper (if using disc brakes)
    • CHALLENGE  If wheel doesn’t fit properly, you’ll need to file the inside of your dropouts a little bit at a time. The spacing should be 10mm.
    • The distance between the forks is generally 135mm. If your distance between the rear forks are too narrow you can gently prise them apart.
  • Install the torque arm to prevent the wheel from spinning out of the forks. The torque arm transfers the axle torque up the forks. See video below on how to install a torque arm.
  • Fit external washer or the lock washer/mounting nut on the chain side. Initially tighten the nuts by hand.
  • Once wheel is running true, and movement on the chain is aligned to your satisfaction,  tighten the nuts with wrench/spanner.
EBIKELING Universal Torque Arm for Electric Bicycle e-Bike Bike Front or Rear Hub Motors and Mid Drive e-Bike
Universal torque arm kit ebike for hub motor installations; A must for high power 1000W+ kits which will be installed on dropouts
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TorqArmV4
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Pedal Assist Sensor (PAS)​ - non-chain side

Pedal Assist System part 3 of eBike Conversions for Beginners
Pedal Assist Sensor Ring & Disc Magnet
  • On the non-chain side of your bike, remove the cap covering the nut, undo the nut either with spanner/wrench or allen key. Take your crank arm extractor and screw it in clockwise and tighten the lower nut (nearest the crank) with a spanner using the crank as leverage. Once it’s firmly in, turn the top nut clockwise holding the crank for leverage – this applies a pulling pressure inside the crank – until the crank arm is pulled off. See video below for crank removal.
  • Once crank is removed, unscrew the outer ring – if you have one – then on the exposed crank shaft slip on the sensor ring and screw the outer ring back on top of it.
Challenges you may face
If bottom bracket doesn’t allow you to fit the sensor easily you may have to cut the sensor ring and mount it using a hose clamp and bend it into position with a pair of pliers. ALTERNATIVELY remove the sensor by unscrewing it from the plate ring and glue the sensor to the frame.
  • Once the sensor is in place then add the magnetic circular disc with the magnets facing outwards ie away from the bike, with no more than 3mm gap between sensor and rotor.
placing magnetic pedal sensor disc over the sensor, eBike Conversions for Beginners
place magnetic pedal sensor disc over the sensor
  • Put the pedal crank back on – CHALLENGE – some bikes may need to have a washer put on behind the pedal crank to make it snug or may have to file around the opening of the crank arm to get it to fit.
  • The cable from the PAS will connect to the PAS cables on the controller
 
NB Some people prefer to install the PAS and disc on the chain side of the bike as it is less visible to prying eyes. However it is far more fiddly as it can involve removing the whole crankshaft. If you do, be aware that on this side of the bike, the disc must have the magnet side facing inwards ie towards the bike.

Install the Battery

  • Install the battery mount to the existing water bottle mount holes. If you don’t have any you will have to drill holes and fit.
  • Fit battery on to the plate.
  • See video below for alternative battery fitting.

Install the Cockpit / Handlebar Area

  • Remove everything from your handlebars
  • Install the LCD display, control switch, throttle and e-brake.
  • You’ll need to remove the cable/housing from existing brakes and install on to the e-brake levers.
  • Put back your gear shifter and grips.
     
    Challenge
    If your bike has an all in one shifter and brakes combined – common on mountain bikes – it means you’ll be unable to use included e-brake levers meant for cutting off motor.
     
    Please see video below for alternative.
  • At this stage we’re going to combine cable management and connectivity.
  • Grab all the wires hanging from the components on your handlebars – ie LCD, switch & throttle –  cable tie or insert spiral cable “tidy” over them following the frame of the bike toward where your controller will be.
  • Do the same thing with the motor cable, battery cable and PAS cable.
  • Take both bundles and thread them into the controller bag through the hole in the bottom of your controller bag.
  • Doing it this way makes it a bit easier to now connect everything to the corresponding cables on the controller.
  • See next section

Install controller and connect the Wires

Controller connectors for eBike eBike Conversions for Beginners
Typical controller wiring
The wires from the controller are color coded and should simply be a case of connecting these to the color coded connectors on the throttle, motor, battery, PAS and LCD. If a connector has directional arrows make sure they line up properly with its corresponding connector.
 
The diagram above shows the connector wires and their functions. Be aware that different controllers may use different colored wiring to what is shown here as there doesn’t seem to be a universal standard yet.  Also understand that many controllers may come with wires that you will never use and are totally irrelevant for your situation. They can be cut off if you wish.
 
Generally speaking, the red wires are positive and the black wires are negative (or ground) and the other colors are in the main, giving or receiving signals from the other components. The thicker the wire the more power it can handle.
 
The most important wires coming out of the controller are:
  • Battery connector – usually made up of 2 thick wires. One red and one black. Increasingly there is third thinner wire which may also be red or brownish as in the diagram. This is the on/off or ignition switch wire.
  • Motor connectors known as three-phase power connectors are yellow, blue and green and tend to have bullet connectors with plastic looking sleeving over them. If after plugging them in, the motor spins backwards swap over the green and yellow wires and it should spin forwards.
  • The Hall sensor wires also for the motor with the small boxy connector will usually have 5 thin wires (sometimes 6 wires) – red, black, yellow, green and blue.
  • Throttle cables are made up three thin wires – red, green and black. If your throttle has a power button or voltage display there will be a 4th wire possibly yellow which plugs into the positive of the switch system
  • Pedal Assist sensor wires are made up three thin wires red, black, blue with small black connector.

Once you’ve finished all your connections, wrap the excess spiralled covered wires around the controller, fit the controller in the bag supplied. Zip up. 

If you read Part 1 of this series you should already have an idea of where you’ll place your controller.

Use the zip ties to tie down your bundles along the frame.

Turn on the battery. Does it light up?  Does the LCD turn on? Does the wheel turn when you turn the throttle? Does motor come on when you turn the pedals?
 
If no, it’s time to do some troubleshooting. If yes, congratulations. You’re now the proud owner of a decent specced bike at a fraction of the cost of retail.

Summary

In summary to complete a successful rear wheel eBike conversion as a complete beginner
  • Prepare the rear wheel hub motor and install
  • Install the pedal assist sensor
  • Install the battery
  • Install the cockpit area
  • Connect everything to the controller and do basic cable management
  • Check everything works
  • Enjoy your new eBike

You can see other step by step guides on converting your bike by clicking on one of the links in the yellow box below – eBike Conversions for Beginners.

eBike Conversions for Beginners series

You might also be interested in reading Bike Accessories You Didn’t Know You Wanted which includes tips and tools to keep your bike and yourself safe on the roads and having a look at the review on eBike specific helmets for fast eBikes

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Last update on 2020-07-25 / Affiliate links / Images from Amazon Product Advertising API