What is a torque arm?
A torque arm is a vital device designed to counteract the high torque levels generated by an e-bike's electric motor, which can cause the axle to rotate within the bike's frame. This issue is very common in both front hub motors and rear hub motors, where the motor's power puts considerable strain on the axle and dropout. Without a torque arm, this force might lead to axle damage, misalignment, and even accidents.
In short:
Torque arms prevent axle movement on e-bikes, used for safety with high-torque motors. They stop axle rotation and prevent damage and accidents. Crucial for e-bikes with a high torque output, especially those over 500W. Installation involves a kit matching your motor's specs and secures the motor against high torque.
Imagine riding an e-bike with a rear hub motor up a steep hill. Without a torque arm, the motor's torque could cause the axle to rotate within the dropout, jeopardizing your bike's stability. With a torque arm installed, you can tackle the hill confidently, knowing your e-bike's hub motor is secure.
Why Torque Arms are Crucial
Installing a powerful electric motor like a hub motor on your e-bike, means it can generate considerable torque during acceleration and hill climbs. Torque arms are usually necessary for motors equal to, or over a 1000 Watt power output. However, we still recommend using them on any hub motor that will draw over 500 Watts and up. Without a torque arm, the axle could twist within the dropout, leading to several issues:
- Safety Risks: In some cases, axle failure could lead to the whole wheel detaching during a ride, causing accidents and even serious injury's.
- Axle Damage: Ongoing twisting can bend or break the axle, causing expensive repairs like having to buy a new frame.
- Frame Damage: Continuous stress may cause cracks to the frame, weakening its structural integrity.
- Misalignment: Axle twisting and deformation can misalign the wheel, causing uneven tire wear, your disc or rim to rub against your brake pads and poor handling in certain cases.
Installing a Torque Arm: A Comprehensive Guide for High-Power E-Bikes
Tools and Materials
To successfully install a torque arm, you'll need the appropriate torque arm kit, which matches your motor's specifications, a Spanner and either a Philips or Flathead screwdriver. Before buying a torque arm kit, measure the axle diameter and length to make sure the torque arm(s) you get will pass through your hub motors axle without any problems. For most common hub motors, ranging from 500W to 3000W, the axle dimensions will likely be 14x10mm. Typically, for high power "Stealth Bomber" motors, such as those rated at 5000W or more, the axle dimensions are usually 16x10mm. Look for 16x10mm or 14x10mm torque arms retrospectively.
Installation Process
- Prepare the Bike: Unplug or disable your battery or make sure your ebike is switched off and not resting on any power buttons or throttle whilst upside down. Remove the rear axle bolts to get clear access to the dropout area where the torque arm will slide into place.
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Attach the Torque Arm: Slide the small piece through so that it rests flush against your frame dropout. Then match the longer piece in the best position for your frame so that it rests against the frame like so:
Repeat the process on the opposite side if your installing 2 torque arms. If your e-bike is equipped with a motor exceeding 3000W, it's strongly recommended to install torque arms on both sides of your hub motor. - Clamp Installation: Tighten any bolts and secure the torque arm(s) against your bicycle dropout (frame) using the any provided hose clamps, or by bolting it directly to your frame if you can. This is crucial for preventing the motor from rotating within the dropout under high torque conditions.
- Tighten the your axle bolts: Once you are happy with where your torque arm is positioned and secured, firmly tighten your back wheel in place.
- Route Cables: Carefully arrange any cables or wires near the dropout to ensure they do not interfere with any moving parts i.e. spokes, tyre, or disc.
- Test and Adjust: Make sure everything is working as it should be, any major misalignments in the back wheel could mean something was not done properly, or you missed out on a washer. Always check for anything unusual after installing to make sure you haven't missed any washers, spacers ect. Give it a spin test!
Installing torque arms, especially on high-power e-bikes, is an essential step making sure you have a safe ride. By taking the time to install a torque arm, you can avoid potential injury's and enjoy a more safer and stable riding experience.
The Benefits of Torque Arms
- Safety: Prevents axle failure and possible wheel detachment.
- Component Life: Reduces stress on axles, frames, and dropouts, prolonging the lifespan of your parts.
- Performance: Keeps your wheel in line.
- Peace of Mind: Keeps your wheel locked into the frame which gives you a sense of clarity, when using high-powered e-bikes.