Crystalyte Hub Motor Review

May 13, 2012

The Crystalyte hub motor is one of the front runners in cheap and powerful hub motors from China.  They are especially well known for their large and heavy performance motors, the 5300 series (currently used in the $12,000 Stealth Bomber).

In the summer of 2011 Crystalyte released a new series that may become a game changer, an affordably priced and rugged hub motor designed with the US market in mind.  The model shaves 10 pounds off the older 5304 series, and a lower price as well. You can find the new Crystalyte motors from some dealers for as low as $280.

The Hx25 is the front wheel version
The Hx35 is the rear wheel version

The front wheel hubs are all designed to allow a front disc brake, an essential on a high speed bike. However, because the front hub motor is built narrower to fit a standard front bike fork, expect a 25% reduction in power when compared to the rear-drive motor.

The “T” in the model name stands for Torque, i.e. faster starts and more climbing power, but less top speed.
The “S” stands for Speed, and indicates that the motor is wound for slower starts but higher top speeds.

Different models of Crystalyte compared

Crystalyte has decided in this new series of motor to adopt many of the features found in the 9C motor clones which have been manufactured in dozens of factories in China. The 9C clones have become a staple product sold in various cheap kits found on the internet and on eBay, but they have many problems in terms of quality control, as well as several small design issues which make them problematic to use in the demanding western e-bike markets. Crystalyte has adopted the 9C design and tweaked it to better fit western users. For example, with the new Crystalyte, disc brakes and rear freewheels fit much easier than on comparable 9C motors.

The Crystalyte borrows many of the favorable design characteristics found in the 9C such as cast (instead of stamped) motor sideplates , and it also has the same proven magnet and stator tooth count. However, one noticeable difference is that the cables do not exit the hub through the end of a hollow axle (the normal method found on most hubs). Instead they pass through a short slot on the axle side near the left side bearing, similar to the Bionx hub pictured below. This is a great improvement for fitting the rear torque arm, which are a must for all rear hub motors, as well as for changing out the wire end-connectors to match a different controller. Now, both of these operations are much easier.

Different motors compared


The Crystalyte is a powerful motor, easily capable of handling 2000 watts without risk of electronic meltdown. Although it’s lighter than the Crystalytes of the past, this motor feels very solid out of the box. Here are the weights of the different motors in this series:

HT2425 weight 12.60 lbs (5.71 kg) FRONT Hub Motor
HS2440 weight 12.88 lbs (5.84 kg) FRONT Hub Motor
HT3525 weight 16.60 lbs (7.52 kg) REAR Hub Motor
HS3540 weight 16.38 lbs (7.42 kg) REAR Hub Motor

Crystalyte on Scale

If you are thinking about buying one of these, you will have a number of choices to make:

  • Front or rear hub motor drive (see our article here)
  • Torque or Speed wind
  • Sensor or sensorless
  • controller options
  • battery pack options

Production Ebikes Utilizing Crystalyte motor
The $9000 Stealth Fighter uses the HS3540 Crystalyte hub motor running 3000 watts at 40-MPH, and Stealth is still is able to cover the warranty. The $8000 Kenny Roberts Picycle which I test rode (see article here)  was made to be dependable, and runs the HT3540 at 40-MPH. The Picycles “Limited” version runs the same motor, but restricted to 30 MPH. Picycles president Marcus Hayes reports that not a single Picycle has been sent back for warranty repair to date. Other bike manufacturers  that are using this sturdy Crystalite platform are Haberbrink bikes, and Hi-Power Cycles.



The $9000 Picycle shown with the HT3540 in the front


High Speed (S) or High Torque (T)

One of the decisions you will have to make if you buy a Crystalyte is whether you want to go with a motor wound for torque or one wound for speed.  Some of the following factors need to be weighed before making a selection appropriate to your needs:

  • Wheel size
  • Battery pack voltage you anticipate running
  • Amperage requirements/limitations
  • Terrain and riding style requirements: will you be climbing a lot of hills or primarily using it on moderate
  • How big of hills do you ride? Off-road or blacktop? Aggressive riding style or around town laidback cruising?
Gearing will change depending on what the size of your wheels are.  A 20-inch wheeled bike will be geared lower than a 29er, which will be geared super high. The more amps and voltage you pump, the more likely you should go with a speed motor for top speed since torque will not be much of an issue. However if your daily commute involves climbing steep grades you are better off with the high-torque motors and smaller wheels, and may want to consider limiting the volts and amps to keep from smoking your motor.

Rule of thumb: The HT is more efficient at lower speed; the HS is more efficient at higher speed.

To Sensor or not to sensor:

The Crystalye hub motor comes either sensored or non-sensored. A sensored motor means you have extra wires going to Hall sensors, which track the position of the rotor and  help control the timing of the motor, especially at low RPMs.

Advantages of sensorless motors:

  • Less things to go wrong. Hall sensors can overheat or get wet and fail.
  • More water resistant
  • Less complicated to install.
  • Less wires to hide, looks cleaner and stealthier.
  • Price is sometimes lower than sensored motors.

Advantages of sensored motors:

  • Sensored hub motors are more efficient
  • Smoother start ups from dead stops (sensorless can have jolting starts)
  • Smooth and balanced all across the RPM range
  • Most e-bike controllers are sensored. (easier to source controller)
  • Runs better at higher voltages

If you are in doubt as to whether to go with a sensored or sensorless motor, then do what most E-bikers do and go sensored. If you decide you don’t want hall wires (or if the Hall wires fail), you can always cut them off and still use a sensorless motor. Manufacturers producing a motor with Halls is a wise choice. It allows the customer to decide what controller they want to use. Also, a customer may already own an expensive controller that requires Halls, saving the expense of having to replace it.

The  Crystalyte and Drag (“cogging”):

The Crystalyte motor is notorious for being very draggy when you are pedaling with no power.
The HT-35 Crystalyte has been tested, and found to have around 50 percent more drag than a 9C clone motor.

If you want your E-bike to freewheel easily when you are pedaling unpowered, you should consider a geared hub such as the BMC hub motor (read our review here).

It is recommended that you use the regenerative braking feature to at least get some payback for this drag.

Regenerative Braking
If your controller is set up for it, you can have regenerative braking with the Crystalyte motor. When I set up my hub, I quickly realized that I was unable to adapt my hydraulic disc brakes to it. I had to then use Avid bb mechanical disk brakes, which bolted on just fine. There will be clearance issues adapting the disc brake onto this giant hub motor.

To utilize the regenerative braking you need an E-brake handle. An E-brake has a wire that connects to the controller and plugs into a 3-pin connector. You then attach your brake cable, just as you would on a normal bike. The slightest movement of the brake handle cuts the motor power off no matter what you are doing with throttle, and then the regen steps in. This system is either completely on or off with nothing in between, and its braking is strong enough that you can feel it. It effectively slows the bike, even on steep downhills where you can just coast with the regen engaged to help moderate your speed as well as force power back into your battery pack.

Regen braking also helps keep your bike brakes from overheating. However, if you need a fast emergency stop the regen isn’t very effective, which is why it’s wise to use both regen and a disc brake on the rear. When you first pull the brake handle the regen kicks in; squeeze it a little more and you start to feel the disc brake grab. The level of regen is pre-set in the controller. Most controllers come from the factory with maximum regen set as default mode, which is ideal for most riders.

Crystalyte Reliability

The Crystalyte has only one moving part (the center bearing), making it extremely reliable when ridden under normal conditions. Only hot rodders will have a problem with the Crystalyte smoking, usually when they repeatedly exceed 2000 watts to the motor. Like most hub motors, the Crystalyte is sealed so that water and dirt cannot get in. Even if water or dirt does manage to make its way into the motor casing, it should not cause the motor to fail. Hot rodders have been known to drill holes in the Crystalyte casing (to aid cooling) and still run the motor off road with no problems.

Hot Rodding a  Crystalyte

A massively modified LFP Crystalyte motor cover

If you want to run serious power to your Crystalyte (high voltage and high amperage), you might want to consider modifying your motor for better cooling. There are a few ways to do this:

  • air holes in cover. Many hotrodders are drilling holes in their cover so that heat can escape the motor. From what they report the Crystalyte continues to run strong this way even when riding off road in dirt and even in wet conditions. They recommend putting some kind of corrosion spray on the motor like corrosion x if using this kind  of system.
  • active air cooling – smaller holes are drilled in the cover and air is pumped through using an airpump with the air line ran through the axle with the electrical wiring.
  • water cooling – air is sprayed on the cover of the motor which has holes drilled in it.
  • oil cooling – a small hole is drilled into the motor plate and a few pints of oil is poured into the motor. This allows for the motor to transfer heat quicker to the cover plates making for faster heat dissipation. Check out this endless sphere  thread for more info.

Crystalyte Noise

If you have not ridden an electric bike before, you will be amazed at the silence of the Crystalyte. It is nearly silent, but you can hear a low rumbling noise, especially at start up when tire and wind noise is not prevalent. The Crystalyte is slightly louder than the 9C motor when run at the same wattage, and about the same noise level of the geared BMC hub motor. However the BMC has a more high-pitched whine where as opposed to the Crystalyte’s low grumble.

Ride Characteristics

The Crystalite definitely feels like a heavy motor, and the bike become rear heavy.  You really feel big bumps especially if running without rear suspension. The motor feels fairly silent and solid. Knowing how robust the motor is gives you confidence when climbing steep or long grades.  The Crystalyte feels as if it is built for abuse so you don’t have to be reluctant about riding her hard.  I really miss the free wheeling effect of my BMC motor when riding the Crystalyte.


Pros and Cons


Very heavy. (16lbs in rear wheel)

Noticeable drag when riding. (no more freewheeling)


A lot of motor for the money.

Super reliable (only one moving part)

Fast when overvolted.

Regenerative braking.

Choosing a controller:

The Crystalyte motor is designed for speeds of up to or greater than 30 MPH. If you don’t need a 30 MPH E-bike, you can go with a much lighter and cheaper solution. But if you are looking for big speed and maximum power, you should run a minimum of 48 volts and may even want to consider a 60 or 72 volt battery pack.

I have ridden with this motor on both 48 volts and 72 volts. At 48 volts / 40 amps (1900 watts) I had a fun E-bike with a top speed of around 30 MPH. At 72 volts/40 amps (2800 watts) I had a 40 MPH speed machine.

The wattage an E-bike puts out is a result of its voltage times amperage.

Crystalyte sells various controllers for this hub motor that are either sensored or sensorless and they have various amp limits. Generally the more mosfets the controller has, the more amperage the controller can put out.

If you are looking for the ultimate performance in an affordable controller, check out, a San Francisco resident who is well-respected in the DIY community for modifying Infineon controllers from China for peak performance.

Most E-bike controllers are designed to run sensored motors. If you buy a sensorless motor you must buy a sensorless controller.

Choosing a battery

Once you have a controller and have decided on what voltage and amperage you would like to run, it’s time to select or build a battery pack to fit your needs. We recommend some kind of lithium battery technology, either lifep04 or lipoly. Read our article on battery selection here.  It’s absolutel critical that the battery pack you select is capable of putting out the amperage you’ll need by reviewing both the pack’s continuous and momentary or “burst” amp ratings. “Continuous” means exactly that, namely how much power you’ll be needing at maximum throttle when climbing or going off road. “Burst” ratings, OTOH, represent momentary maximum power draws of just a few seconds, typically when accelerating with a wide open throttle from a dead stop. Burst demands can be almost double continuous, and are always measured in amps.

Make no mistake: If you buy an underpowered pack you can be sure it will be destroyed in short order should you push it repeatedly above its amperage ratings. And be forewarned that most Chinese battery makers vastly overstate the power ratings of their packs. The Endless Sphere forum is the best place to do your homework before ordering any pack given the wide discrepancy in manufacturing quality amongst brands.

Other possible accessories:


Battery bag of some kind

Torque arm (especially if going for front wheel hub)

Special ebike brake lever especially if regenerative braking is wanted

7 or 8 speed freewheel cassette for back (9 won’t fit)

Cycle-Analyst for monitoring battery (see article here)

Eric has been involved in the electric bike industry since 2002 when he started a 6000 square foot brick and mortar Electric Bike store in downtown San Francisco. He is a true believer that small electric vehicles can change the way we operate and the way we think.


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