If you are an electric unicyclist, then you will have experience with electric hub motors. These e-motors can be found in many different types of electric unicycles and provide the power needed to move the device.
This article will discuss symptoms of bad bearings in a hub motor as well as suggestions for fixing this issue and safety concerns associated with bad bearings.
What is an Electric Hub Motor?
Hub motors are the mobility power source for electric unicycles. They provide the torque needed to move the wheel and come in a variety of shapes, sizes, and capacities. Hub motors can be found in all types of electric unicycles and have varying amounts of power, often measured in watts.
Hub motors are often used in tandem with regenerative braking which allows them to recharge their own battery while decelerating or breaking to slow down on a hill or when coming down from speeds greater than 20 mph. This is because hub motors do not produce any electricity on their own so they need a way to recharge themselves as they use it up during operation.
The size and type of hub motor will depend largely on the intended use for your electric unicycle. If you are looking for a high performance electric unicycle, then it will be fitted with larger hub motors that produce more power than smaller hub motors which may not provide enough speed and acceleration to keep up with the demands of an experienced rider
In addition to powering your vehicle, they can also double as regenerative braking systems when used in tandem with this technology.
Pro Buyer’s Tip: Nominal vs Peak Wattage in Electric Hub Motors
Electric motors are rated “nominally” by how much power can be safely output without overheating. This is subjectively determined, and it’s always better to err on the side of caution when considering what your motor needs in order not to burn out from overuse or heat up too quickly.
The limits placed upon human beings with regards uninterrupted versus intermittent power output, e.g., cyclist in the Tour de France, also applies well to electronic devices, such as electric hub motors in e-unicycles. A motor has a nominal rating (wattage) that reflects their ability potentially stay intact after being put under strain. This can change, however, depending on an the wheel design, battery power, software design, and other factors.
Peak output of an electric unicycle hub motor maybe up to double or more than that of the rated nominal power of the motor. But, as you may expect, running a hub motor above the nominal rating will eventually damage the unit, usually starting with high temperature overheating. The peak motor output rating of an electric unicycle will determine how steep a hill you can climb, or how quickly you can accelerate at different speeds, e.g., torque.
There is a lot of confusion about how different motors work. For one, you can get different power ratings for the same motor depending on what type of measurement your EUC brand uses. One example would be peak watts vs nominal wattage. While these two measurements sound like they measure very similar things there are actually significant differences between them that might have implications in other areas such as price point or durability over time. Not all companies provide both types of data and it’s impossible to know which number reflects reality without looking up their technical specs online with every product listing you come across!
What is the Function of the Bearings in an Electric Hub Motor?
A set of bearings helps the motor to run smoothly and achieve maximum power. They allow for safe operation of the electric unicycle and prevent friction between internal components of the hub motor. There are two different types of bearings that may be found in an electric unicycle–one is a light-bearing, which is often called a sleeve bearing, and the other is a heavy-bearing which can sometimes include ball bearings.
Light-bearings typically provide more protection against abrasion but have less load capacity than heavy-bearings. In addition, light-bearings typically cost less than more robust bearings which can lead to more frequent replacements.
Both types of bearings are vital because they act as shock absorbers between the motor shaft and the wheel, helping to reduce vibration that can be transferred into the hub.
What are Some Symptoms of Bad Bearings or Wheel Issues in an Electric Unicycle?
There are several symptoms of bad or worn out bearings in the hub motor of electric unicycles. Here are a few common issues that may arise with your electric unicycle hub motor, wheel, or tire.
1. Knocking, clunking, snapping or clicking sounds while riding
You may be hearing a worn or damaged outer Constant Velocity (CV)-joint, which may or not play a part in your particular unicycle. This relates to the axle interface with the motor. Here, your hub joint could may just need to have its bearings tightened up with the clamps so they are not too loose and rattling around in there. This noise is typically heard when cornering, making turns that require quick acceleration (rather than slow gradual turn).
Ultimately, the noise you hear while riding involve either excessive play from bad balancing of the axle bolts/nuts, which leads to endplay and cause more vibration during maneuvers like turning corners as well as accelerating quickly versus gradually braking down onto sharper turns–pretty much any maneuver where rapid changes in speed happen often and abruptly such as sharp curves
2. Grinding when you’re riding the electric unicycle
As your electric unicycle starts to make strange noises, it is important that you take a closer look at the issue. The likely source of these grinding sounds will be from mechanical damage in either one or both of two parts: axle bearings and wheel/hub-end systems. In most cases this means there has been some kind of external force put on them which caused material loss such as roller wear or bearing overheating due to lackadaisical maintenance practices like failing to lubricate the moving parts, for example.
3. Low frequency humming
In contrast to “grinding”, this annoying sound may be due to an underinflated off-road tire. In this case, simply inflating your tire to proper air pressure can solve this innocuous issue. But a constant humming or growling within the hub motor itself, may suggest electrical or drive train part problems. In other words, this may mean your bearings are in need of replacement. The humming/growling may get better when you’re rolling off-axis, e.g., turning, and get worse when you’re riding straight. Or, you may find a particular side is worse sounding than the other when you’re corning; in this case, you’ve found the problem side on your wheel.
4. Excessive wheel vibration or wobbles
On an electric unicycle, quality control issues may lead to poorly installed and assembled wheels, tires, or motors. The symptoms of excessive wobbling or vibration of your electric unicycle can be a result of various things such as damaged or worn tire, wheel or a suspension component. One that is more severe would be the chassis being misaligned to where it’s at an angle. This may not be a big problem, but could be a cause for concern if lug nuts had not been tightened enough on one side of your unicycle. This could eventually lead up to some serious damage, a crash, and in turn costly maintenance down the line.
Another thing that may disrupt a smooth electric unicycle ride is anything related to mechanical faults or failure within the hub bearing clamps. This could underlie all sorts of extreme wear and tear within the motor hub. At this point, a complete replacement of the hub motor may be necessary for safe and comfortable riding of your electric unicycle.
5. Uneven tire wear
The most common source of abnormal tire wear is improper inflation, which may lead to problems with alignment. In addition, a worn or damaged axle or chassis, which can cause irregular movement of the rotating hub. This may be subtle at first, leading to gradual tire wear on one side of your electric unicycle. Abnormal wear on your tire may also be a related symptom to other issues above.
How Do I Avoid Bad Bearings in an Electric Unicycle?
In some cases, bad bearings could be due to poor manufacturing processes, faulty design, and subpar quality control measures at the factory side. Here, the best recommendation is to purchase your electric unicycle through a reputable third-party dealer with a robust after-market warranty. Yes, you will pay more than if you purchased direct from the electric unicycle factory, but the long term (or short term) benefit is clear, especially with electric unicycles, a niche technology.
One preventive measure that may help is to periodically check and lubricate the axle bearings with a light oil. When you open your electric unicycle for it’s regular checks (which I recommend you do every few hundred miles), you can add this lubrication to exposed areas around your hub motor. I do not recommend exposing your bearing encasement (often it is packed with grease), unless you know what you’re doing with your particular unicycle model. You may also want to check with your vendor to see if this type of maintenance you perform yourself will void your warranty or not.
Another thing you could do to minimize damage is to make sure your electric unicycle tires are properly inflated. If the tire pressure is too low, it will put more strain on your bearings causing them to wear out faster. You can also look out for any wobbling, shaking, or grinding when you’re riding your electric unicycle wheel. These may be signs that there’s something wrong with your hub bearings and you need to have them repaired or replaced if they’ve been damaged in any way. Even if your hub bearing starts making a new noise, it’s always a good idea to have them checked out.
As you continue riding your electric unicycle over time, you may notice other symptoms of bad hub bearings such as irregular tire wear or excessive wobbling when the wheel is spinning. If you notice any of these symptoms, or other unusual behavior from your electric unicycle, it’s a good idea to have the hub motor inspected as soon as possible.
Finally, unless your electric unicycle is rated for water exposure, avoid getting your wheel motor hub wet. Submerging or exposing your hub motor in water during riding can allow debris and moisture into your motor bearing case. This can lead to abnormal wear and tear, as well as accelerate corrosion and oxidation within the hub motor. This will degrade your electric motor, significantly reducing its service life.
Are Bad Hub Bearings Considered a Safety Issue?
Hub motors that have worn or damaged bearings may cause the wheel to stop spinning due to the lack of lubrication and/or overuse. The rider could also suffer from an accident if he or she rides the unicycle and is unable to predictably and controllably stop if the EUC hub motor fails in any way.
Excessive noise or squeaking coming from the wheel hub may be a sign of bad bearings in your EUC motor. If you notice this symptom, it is best to have someone inspect the unicycle for damage and/or poor lubrication before riding again as it could cause an accident if continued to use without stopping.
A less serious problem with bad bearings or fault within the hub motor of an EUC is reduced riding efficiency. With increased friction, there’s additional heat and wear on the motor. This can reduce the range of your electric unicycle. The increased current (amperage) demand from the inefficient, defective motor unit, can drastically diminish the life of your other electronic components, including the battery and control board.
Summary: Suggestions for Preventing and Solving Bad EUC Bearings
- The best recommendation for avoiding bad bearings is to buy your electric unicycle through a reputable third-party dealer with a robust after-market warranty
- Another thing you could do to minimize damage is to make sure your electric unicycle tires are properly inflated. If the tire pressure is too low, it will put more strain on your bearings causing them to wear out faster
- As you continue riding your electric unicycle over time, you may notice other symptoms of bad hub bearings such as irregular tire wear or excessive wobbling when the wheel is spinning. If you notice any of these symptoms, or other unusual behavior from your electric unicycle, it’s a good idea to have the hub motor inspected as soon as possible.
- Unless your electric unicycle is rated for water exposure, avoid getting your wheel motor hub wet. Submerging or exposing your hub motor in water during riding can allow debris and moisture into the encasement of the bearing causing abnormal wear and tear as well as accelerated corrosion and oxidation within the center bearings which will degrade the electric motor significantly.
- To maintain the best performance, it’s always a good idea to have your electric unicycle serviced by an authorized repair center from time to time.
Don’t let bad hub bearings on your electric unicycle ruin the fun of riding. By following these simple steps for identifying and suggestions for fixing a problem with your wheel hub motor (or tires), you can keep it in excellent condition and enjoy years of fun without having to worry about safety or comfort issues.
I am always on the lookout for ways to improve our enjoyment with the electric unicycle, and would love to hear from you!
Do you have any experience with a bad bearing, worn out motor, or tire/wheel issue? How did you resolve the problem and was it costly? Let me know with a comment.