Everything about the HELRGELRN rear fat 1500W kit lives on its spec sheet, because almost nothing lives in the review section. Two buyers have rated it, averaging 2.5 stars, and both report the gap between claimed watts and delivered performance. This is a caution-flag review for a kit priced like a bargain and performing like an experiment.
Specs and Value
This entire conversion kit revolves around a 1500W rear hub motor. The high wattage output indicates a huge amount of torque. That kind of torque will allow you to climb steep hills and clear obstacles with ease. However, a higher power draw tends to produce excessive heat in the motor's housing during extended periods of use. Low-quality internal windings may cause overheating and render the motor useless after a few miles of intense pedaling uphill.
The LCD display provides access to your speed and remaining battery life. Your ability to monitor your power consumption is completely dependent upon this display. There is a good chance that the wiring may be fragile. Flickering or complete failure of the display mid-ride may occur due to brittle wiring, and you will then be left with a large, heavy manual bike to push.
Your decision to purchase this kit is purely based on the raw numbers listed in the Amazon description. The 1500W motor is substantially more powerful than the typical 500W motors utilized in most entry-level kits. More power equates to faster acceleration from a dead stop. However, there is also the possibility that the controller will deliver power jerkily or shut down when you apply full throttle. You are purchasing the opportunity for high-speed riding rather than the reality of the components' quality. Due to a very limited number of reviews available, you are essentially one of the initial test subjects for this particular batch of hardware.
Mounting and Fat Tire Fit
This kit targets fat-tire bikes on 26-inch wheels, the usual platform for snow and sand builds. To accommodate these wider tires, the dropout widths must be broad enough. If your frame is a standard mountain bike design, this motor will not fit inside your frame's axle area. The addition of a rear hub motor increases the weight located at the back of your bike. This weight shift affects your bike's handling and causes your front end to feel lighter than normal. You must determine whether your frame is strong enough to withstand the torque produced by a 1500W motor without distorting.
To install this kit, you replace your current wheel with this assembled wheel unit containing the motor. Installing this type of kit is far from being easy for someone who does not own a bicycle tool set. Inadequate tightening of bolts may result in the motor losing traction while under load, resulting in catastrophic damage to your frame and/or serious injury due to loss of control.
In addition to ensuring proper bolt tightening, you also require sufficient cable length to connect to your battery mounting location. Insufficient cable length will subject the connectors to constant vibration as you ride, ultimately causing a short circuit.
When comparing a 1500W hub motor to a standard wheel, the mass and rotational inertia associated with a 1500W hub motor are substantial. By adding this additional mass along the circumference of the wheel, your bike's acceleration and deceleration characteristics are altered. Additionally, cornering speed may decrease due to increased mass at the periphery of each wheel added by fat tires. With the motor adding even greater weight to both ends of your bike, you must evaluate whether your braking system is able to safely bring your bike to a halt.
Speed, Range, and Battery Demands
A primary advantage of this 1500W configuration is raw power. High-power motors consume more energy than lower-powered designs more quickly. Using a low-capacity battery greatly limits the distance you can travel using motor-assisted propulsion. Under heavy loads (such as climbing) and when you pedal aggressively, your battery may drain rapidly. On flat sections of road, this motor produces sufficient power for fast cruising. However, increased speed decreases battery life and places additional thermal stress on the motor.
Torque produced by the rear hub is ideal for traversing terrain types including snow or sand. Traction for your fat tires plus the forward thrust provided by the motor allow you to overcome obstacles that other ebikes cannot. However, if the motor lacks precise gradability, it may lose traction and spin freely in loose terrain conditions. Freewheeling in situations where you need maximum mobility is unacceptable. Therefore, you trade-off fine control for brute force, and hope that all component parts can withstand extreme stresses.
High-wattage configurations place incredible pressure on the battery pack. Constantly operating at 1500W will quickly deplete voltage and cause premature disconnection of the controller prior to total depletion of the battery. You need a high-discharge-rate battery pack to take full advantage of this kit. Without the appropriate battery source, you are merely paying for a 1500W spec sheet number.
What Amazon Reviewers Are Saying
Two ratings, 2.5 stars each, and neither buyer saw the performance the listing promises. With a sample this small, nobody can say whether both units were lemons or the whole batch disappoints. What you can say is that neither early buyer got what they paid for.
The complaint both reviews share is the watts gap: a listing that says 1500W delivering performance closer to a mid-grade motor. Whether the HELRGELRN rear fat kit deserves the benefit of the doubt is exactly what future reviews will decide. Inflated wattage claims are the oldest trick in the conversion kit market, and with no independent testing here, there is nothing proving otherwise.
Who Should Buy This
The only buyer this suits is an experienced mechanic building a snow or sand bike who accepts that the rating history says the watts may be fiction. If you possess a fat bike measuring 26 inches and need that raw strength to tackle difficult terrain obstacles, this option may suit you. You should be knowledgeable about mechanics and accustomed to troubleshooting when problems arise during operation.
Skip it if you want plug-and-play. The 2.5-star rating and minimal number of reviews suggest that this product has not been thoroughly vetted for every user. Commuters utilizing their e-bikes daily for transportation purposes do not want a product with an uncertain history or potential for failure during peak hours.
Compare it against the rest in our ebike conversion kit guide, or dig through the GoMotorbikes blog.
Check the latest price on Amazon.
Frequently Asked Questions
Five quick answers before you order. This kit is for people who want to ride their fat bikes through snow without experiencing slippage and lack of traction at every corner. Using a 1500-watt rear hub motor in conjunction with 26 x 4.0 fat/snow tires converts your seasonal bike into a winter bike. Commuters who regularly ride in cold weather or utilize their fat bikes on beaches or snow trails will find value in this product.
Is This Kit Suitable for Casual Commuters?
No. This kit was developed for extreme commutes in harsh conditions and has been designed for serious cyclists. While this kit can perform well in mild conditions, it is intended for aggressive use. For example, casual commuters who merely desire a gentle boost while riding on paved roads will want to consider smaller motors (i.e. 250 - 750 watts).
Does the Kit Include a Battery?
No. The kit includes a pre-built motor wheel along with all necessary electronic components except for a battery. You will need to select and purchase your own 48-volt battery that corresponds to the required wattage of yourthis kit. A weak battery will severely restrict performance regardless of how powerful the hub motor.
How Realistic Is the Claimed Top Speed?
While the claimed top speed of 55km/h is accurate (with respect to actual motor capabilities), there are several factors that affect maximum achievable speed including rider weight, tire pressure, air resistance and condition of battery. In milder conditions with lighter weights, etc, this motor can achieve higher speeds.
Do I Need a Torque Arm?
Yes. Because the Helrgelrn is a gearless hub motor capable of producing massive amounts of torque (over 180 ft/lbs) it is imperative that you utilize a torque arm in order to prevent destruction of your frame from excessive rear axle movement.
What Makes This Kit Different from a Geared Hub Motor?
One of the primary advantages of gearless direct drive hub motors is that they contain far fewer moving parts than geared hub motors. Since there are few moving parts in a gearless hub motor (i.e. none internally), there are also fewer opportunities for them to fail (due to wear & tear) when subjected to high mechanical loads (i.e. constantly fighting snow). The primary disadvantages of direct drive hub motors are their size and weight. They are generally larger and heavier than equivalent sized geared hub motors.
Therefore, because most riders utilizing their fat bikes in snowy conditions will be commuting at slower speeds than faster speeds encountered in warmer conditions or smoother surfaces, riders will benefit from the added torque produced by direct drive motors.