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What is a torque arm and why do I need

What is a torque arm

The torque arm is an additional support metal piece added to the bicycle frame to more firmly fix the shaft of the powerful hub motor. But let’s go back and learn more about torque arms in general to understand when they are needed and why they are so important.

Many people choose to convert standard pedal bicycles to electric bicycles to save on the cost of buying retail electric bicycles. This is a good choice for many reasons, and it’s very easy to do. Many manufacturers have designed simple electric bicycle conversion kits that can be easily bolted to a standard bicycle to convert it into an electric bicycle. The only problem is that the poor guy who designed your bike plans to use it with light bike wheels instead of huge electric hub motors. But don’t worry, this is where the torque arm comes in!

The torque arm helps your bicycle rear fork (the part of the bicycle fixed on the axle) to resist the torque of the electric hub motor. You see, ordinary bicycle wheels do not apply too much torque to the bicycle rear fork. The front wheel does not actually apply any torque, so the front fork of a bicycle is designed to simply fix the wheel in place, rather than resist its torque, while providing power to the bicycle through the power of multiple professional cyclists.

The rear wheel on a standard bicycle does traditionally exert a small amount of torque on the hook, but it does not exceed the torque that the standard axle bolts clamped on the hook can withstand.

The torque arm adds strength to the weaker bicycle frame

However, when you replace electric hub motors, torque becomes an issue. Small motors of 250 watts or less are usually good. Even the front fork can handle the low torque of these in-wheel motors. Once you start to reach about 500 watts, there will be problems, especially when we talk about front forks, especially when the material is weak, such as aluminum forks.

In this case, a torque arm is needed to resist the torque of the in-wheel motor. Torque arms come in various shapes and sizes. Some are mass-produced, one-size-fits-all styles. They slide on the motor shaft and are then clamped or bolted to the bicycle frame to provide a firm connection to the bicycle farther than the surface of the axle.

Other torque arms are customized jobs by men and girls in their garages, especially for their own bicycles and motors. One thing in common for all these torque arms is that they grab the flat part of the motor shaft and connect to the bicycle frame in a strong manner to help resist the torque forcing the disconnect pawl to open.

when do you need a torque arm

First of all, if you are buying a retail, commercially available electric bicycle, then you don’t need to worry about the torque arm. If necessary, the designer of the electric bicycle will already include one, or it is more likely that the bicycle will be designed as a dedicated electric bicycle with a sufficiently strong rear fork, without the need for a torque arm.

However, if you are modifying your own electric bike, you may need a torque arm, depending on the type of bike and the power level of the motor.

As mentioned above, the front and rear in-wheel motors have different requirements. The front fork is usually much weaker than the rear fork. This means that the front hub motor is more likely to require a torque arm than the rear motor.

Secondly, the frame material plays an important role. Steel is a stronger material than aluminum and can resist bending more easily. This means that if you combine the steel rear fork with the rear hub motor, your position is much better than the front aluminum fork.

Torque arm specifications

Three main factors control the effectiveness of the torque arm, so you need to pay close attention to these factors when buying or making your own torque arm. The first is the choice of materials. If possible, look for a stainless steel torque arm. They are even stronger than the mild steel or aluminum used in your bicycle frame.

Secondly, the thicker the better. always. You want as much meat as possible to grab that shaft. Try to find a good thick torque arm. I have seen a thin torque arm cut a gap around the axle, but still allow it to rotate, thus damaging the bicycle and the motor. A quarter inch (0.635 cm) is a good torque arm thickness. Of course, the thicker the better.

Finally, the farther the torque arm is mounted on the bicycle, the better. A torque arm that is one inch long is good, two inches is better, and three inches is better. The farther the torque arm is mounted on the frame from the axle, the greater the force it can resist.

If you are in a critical juncture, or you really want to make your own, a 10 mm adjustable wrench can make a very good torque arm. Just make sure that the wrench does not interfere with the firmly closed shaft nut in some way.

If you are in a critical juncture, or you really want to make your own, a 10 mm adjustable wrench can make a very good torque arm. Just make sure that the wrench does not interfere with the firmly closed shaft nut in some way.

The torque arm can protect your motor and bicycle. The cost of not using a torque arm when you should use it is very high: usually a damaged motor and/or a damaged bicycle frame. You can avoid this tragic ending by ensuring that you have the right tools for your electric bike manufacturing, including knowing when to use the torque arm.

Torque arm will help prevent the motor from coming loose from the front or rear and also prevent the slotted axle from bending or breaking your dropouts.

Additionally, these versatile torque arms can be installed inside the frame/fork or outside.

Inside or outside mounting is not always possible depending on your particular setup.This quad torque arm kit will provide you double protection for two bikes, or one dual motor/AWD bike, on both sides of the front fork and/or rear frame for maximum protection.

If you are interested in motorized bike and want to know more, you could browse previous articles or visit our Official Website, also choose to leave your message below. If you are interested in electric bike, you can contact us.

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