Jupiter Electric Bikes Support

If you find you have to pull hard on the brake lever to slow down, or it squeezes right into the handlebar, it's likely your brake cable needs adjusting.

There are two main points of adjustment for your cable-based disc brakes. One is at the caliper and the other is the barrel adjuster. The caliper is the claw-looking device at the disk in the centre of your wheel. The barrel adjuster is the metal cuff on the brake cable at your brake lever.

Pull the brake lever to check the tightness of your brakes

The clearest giveaway that something is wrong with your brakes is if the brake lever is too tight or too loose.

If the lever touches the handlebars, the brake cable is too loose. If you can barely squeeze it at all, the cable is too tight. Ideally, the brake lever should squeeze 1 to 1.5 inches before becoming difficult.

Tighten or loosen the barrel adjuster accordingly

After diagnosing whether your brake cable is too tight or too loose, you can make minor adjustments using the barrel adjuster. Tighten or loosen the barrel adjuster by turning it clockwise or anti-clockwise. This will increase or decrease tension in the cable.

Once you've tightened or loosened the barrel adjuster accordingly, give the brake lever another squeeze to see if it's fixed the issue.

Top tip: Tightening or loosening the barrel adjuster is a quick and easy way to address braking issues if you're out on a ride. Even if it doesn't solve the problem, it might improve the situation long enough for you to get home safely and fix it properly.

Loosen the bolt on the brake caliper to readjust

If the brake lever is still too tight or loose after correcting the barrel adjuster, the cable may be too tight or loose on the brake caliper.

Take your Allen key and loosen the cable from the caliper by turning it anticlockwise, taking care not to entirely unbolt it as you'll find yourself having to reassemble the brake.

Pull or release the brake cable through the caliper

Once the caliper bolt is loose enough, it should spring back away from the wheel and cable. From here, you should pull the cable outward to tighten the brake, or allow the cable to retract inwards to loosen it.

The cable threads through a lever on the caliper that moves when you apply the brakes. When you tighten the cable, make sure the lever still has enough room to move and can't reach back so far as to hit the caliper. If it does, your braking will be obstructed and the pads won't reach the rotor. Skip to 1:11 in the below video for a demonstration of this.

Tighten the caliper bolt back up

When you've found the spot your brake pads sit comfortably over the rim and the cable is tight, screw the caliper bolt back up and give your brakes a squeeze. If they're still not quite right, it's worth revisiting the barrel adjuster to make final tweaks to loosen or tighten the brakes.

Stay safe while cycling

Knowing how to adjust your bike brakes will help you safeguard your bike in the long run. Please always make sure your brakes are working properly before riding, and always wear a helmet.

Straightening Your Brake Rotor (Truing)

A warped rotor on disc brakes can cause loud noises while braking and squeaking while riding. Warping can happen from normal use, abuse, or simply by it getting too hot. A bent rotor is often the result of a direct impact when parking or storing the bike. If a rotor is badly bent, it's best to replace it.

It can be hard to determine if your rotor is repairable. If your rotor doesn't show any signs of improving after several minutes of working, then it's probably time to get a new rotor. When a rotor gets too worn it will not be possible to make it straight again. Use caution when working on rotors as their edges can be sharp.

Noise from the brake is often a sign that the rotor needs to be straightened

Before you start, check wheel alignment and play in the bearings. If the wheel isn't seating properly or the bearing allows the wheel to rock, then this is probably your issue, not the rotor.

Other issues that can cause rotor rubbing are:

Misaligned brake calipers — see How To Adjust Brake Cables.
Brake mounts on the frame may need to be adjusted / refaced. You will need a special tool for this, or high end bike shops will have it.
Loose rotor mounting bolts or a loose lockring.

Straightening Your Brake Rotor (Truing)

Straightening the rotor can often be done while keeping the wheel on the bike by watching the rotor move through the brake caliper.

Set the bike upside down on the ground in order to get the wheel spinning freely.

Watch for wobble at the caliper between pads. Look for the opening and closing of the gap. Find a section of the rotor that needs truing, and note which way it needs to be bent to correct the runout. Use a flashlight if you need more light.

Rotate this section of the rotor out of the caliper.

Use a rotor truing fork tool to flex the rotor in the appropriate direction in order to improve the bend. Always begin with a small amount of effort on the tool, and then apply more effort if no improvement is seen.

Spin the wheel and sight the rotor again. Repeat as necessary. When the rotor is not rubbing the pads as it spins, it is adequately straight.

My Jupiter Bike Will Not Power On

You've read the instructions, pressed & held the power button, but your Jupiter Bike will not turn on. 3 quick things to check for this are:

1. Is the bike frame closed and latched.
2. Is the battery in the frame.
3. Does the battery have a charge.

If this doesn't solve the issue, please read on and try the follow more advanced troubleshooting.

1. Check if the LCD Cable Became Unplugged

Some Jupiter Bikes have an inline cable plug a few inches south of the LCD display. This 'quick connect' cable was designed to allow the user to easily replace the LCD display if it got damaged, unfortunately it's also the #1 reason that the bike will not start.
To troubleshoot: Unwrap the cable coil holding the LCD cable, on the left side of the hanlebar. Look for a plug that is part of the cable that has become unplugged - and re-connect it.

2. Check the Battery Prongs

Your bike uses 4 or 5 metal prongs to pull power out of the battery. If one of those prongs get bent, the bike can not get power.
To troubleshoot: Unlatch the bike frame, fold the frame in half and check the battery prongs. If one (or more) of them are not straight then take a pair of pliers and straighten the prong. Slowly close the frame, making sure the prong properly aligns with the battery terminal. The bike should easily close and latch with no excessive force. Re-fold the bike to make sure the prong is still straight. Close the bike again, and hold down the power for a few seconds to turn it on.

How to Replace a Tire or Tube

Watch this step by step video on tire and tube replacement. Defaint bike is shown, but the steps and concepts can be adapted for any Jupiter Electric Bike.

How To Replace Brake Pads

When to Replace Your Brake Pads

You should replace your brake pads when they get worn out. Your pads should measure at least 1 mm thick, if they are less than that then it's time to replace them.

Another reason to replace pads is if the pad becomes contaminated with oil or grease. The contamination is not always easy to see. Contaminated pads may cause your brakes to squeal and can show as darkness on the rotor and pads that smear when rubbed with your finger.

Brake Pad Replacement

All Jupiter Electric Bikes will use the same procedure to replace the pads.

Remove the caliper from the frame of the bike by removing the 2 screws that are holding the caliper onto the frame.
Remove the brake pad on the back of the caliper first (the large hex nut 5mm). do not lose the magnets.
With a flat-head screwdriver, remove the brake pads from both the left and right sides of the caliper.
Take the new brake pads and insert them into the caliper. Put the 5mm hex nut back onto the back side of the caliper and reinstall it onto the frame of the bike.
Adjust the caliper as needed for optimal brake tension.

How to Replace the Bike Throttle

Tools Needed

3mm Hex Wrench (Allen Key)
5mm Hex Wrench (Allen Key)
Phillips head screwdriver
Windex or other Glass Cleaner

NOTE: Before removing wires from the controller, take a picture of the wires and where they go so that there is no confusion when installing new components and what wires they should be plugged into. The recommended method is to install each wire on the controller one by one in the event of a complete controller swap.

Throttle Replacement

All Jupiter Electric Bikes will use the same proceedure to replace the throttle.

Start by removing the handlebar grip. This can be done by spraying some Windex around the edges of the grip and twisting the grip to work the Windex underneath. Continue to twist and pull until the grip comes off of the handlebar.
Loosen the Phillips head screw on the Shifter (if applicable) and loosen the 5mm hex screw on the brake handle. Do not remove the screws from these components, just loosen them up enough so that they slide off of the handlebar with ease.
Undo the wrap that goes around the wires all the way to the underside of the bike. There will be a hole where all the wires meet. That hole is the controller compartment.
Open the bike to access the controller compartment. There will be 5 leads on a black plate with screws. This is the controller male plug. Remove the 5 screws from the plate to take the male plug off.
Remove the bundle of wires inside the controller compartment.
Remove the silver box (controller) from the controller compartment.
Trace the old throttle wire from the throttle to the controller and mark the wire on the controller, then unplug the old throttle from the controller, and remove the wire from the controller compartment pulling the wire out of the hole on the underside of the bike.
Run the new throttle wire into the controller compartment from the underside of the bike and plug it into the marked wire of the controller.
Run the new throttle wire under the bike and up along the handlebar stem, and slide (in this order) the brake lever, the shifter (if applicable), and the throttle into place.
Spray Windex directly onto the handlebar and reinstall the grip, sliding and twisting it into place.
Tighten down all components and wrap the wires with the same wrap the wires were wrapped with.
Put the controller and wires back into the controller compartment, and reinstall the male plug.
Test the bike to see if the throttle works by leaning the bike onto the kickstand so that the rear wheel is slightly off the ground, and twisting the throttle.

Product Support

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Please reach out to us if you need more support.