Varstrom EC38-FO Crank Arms User Manual

1. Product Overview

The Varstrom EC38-FO Crank Arms are high-quality aluminum replacement parts designed for electric bicycles. These 170mm crank arms ensure optimal performance and a precise fit with various e-bike motor systems. They are engineered for durability and compatibility, providing a reliable connection for your e-bike's drivetrain.

A pair of black Varstrom EC38-FO aluminum crank arms, designed for electric bicycles, featuring a square taper interface.

2. Compatibility

These crank arms are designed for broad compatibility with several popular electric bicycle motor systems. It is crucial to verify your motor model to ensure proper fit and function.

• Shimano E5000/E6000: Developed to integrate seamlessly, ensuring optimal performance and precision fit.
• Yamaha PW-SE/PW-TE: Engineered to provide a smooth and efficient user experience.
• Panasonic: Designed to enable a secure and powerful connection, enhancing overall functionality.
• BAFANG M300/M400: Specifically adapted to offer a precise fit and high performance.

Important: Always check your motor model before installation to confirm compatibility.

3. Setup and Installation

Proper installation is essential for the safety and performance of your electric bicycle. If you are unsure about any step, consult a professional bicycle mechanic.

3.1. Required Tools (Not Included)

• Crank puller tool
• 8mm Hex key or 14mm/15mm wrench (depending on crank bolt type)
• Torque wrench (recommended)
• Grease (for spindle and pedal threads)

3.2. Installation Steps

1. Preparation: Ensure your e-bike is stable, preferably on a repair stand. Remove the old crank arms using a crank puller tool. Clean the bottom bracket spindle thoroughly.
2. Grease Application: Apply a thin layer of bicycle grease to the square taper spindle of your motor and the inside of the square hole on the new crank arms. This prevents creaking and corrosion.
3. Crank Arm Alignment: Slide the new Varstrom EC38-FO crank arms onto the square taper spindle. Ensure they are correctly oriented (left crank arm on the left side, right crank arm on the right side, typically opposite the chainring). The square hole should align perfectly with the spindle.
4. Secure Crank Bolts: Insert the crank bolts into the crank arms and tighten them. For square taper cranks, it's crucial to tighten these bolts securely. Use a torque wrench if possible, following your motor manufacturer's recommended torque specifications (typically around 35-45 Nm). Overtightening can damage the spindle or crank arm, while undertightening can lead to loose cranks and damage.
5. Install Pedals: Apply a small amount of grease to the pedal threads. Note that the left pedal has a left-hand thread (tightens counter-clockwise) and the right pedal has a right-hand thread (tightens clockwise). Screw the pedals into the crank arms and tighten them firmly with a pedal wrench.
6. Final Check: Spin the cranks to ensure smooth rotation and no wobbling. Check that all bolts are securely tightened.

A detailed view of the square taper spindle interface on the Varstrom EC38-FO crank arm, showing the precise machining for connection to the bottom bracket.

A close-up shot highlighting both the threaded hole for pedal attachment and the square taper interface for the bottom bracket on the Varstrom EC38-FO crank arm.

4. Maintenance

Regular maintenance will extend the lifespan of your crank arms and ensure safe riding.

• Cleaning: Periodically clean the crank arms with a mild soap and water solution. Avoid harsh chemicals that could damage the finish.
• Bolt Tightness Check: After the first few rides (approx. 50-100 km) and then every few months, check the tightness of the crank bolts and pedal bolts. Loose bolts can lead to damage to the crank arms or spindle.
• Inspection: Regularly inspect the crank arms for any signs of damage, cracks, or excessive wear. If any damage is found, replace the crank arms immediately.
• Lubrication: Ensure pedal threads are greased during installation. Re-grease if pedals are removed and reinstalled.

5. Troubleshooting

Here are some common issues and their potential solutions:

• Creaking Noise from Cranks:
  • Cause: Loose crank bolts, dry spindle/crank interface, or loose pedals.
  • Solution: Re-tighten crank bolts to specified torque. Remove crank arms, clean and re-grease the spindle and crank arm interface, then re-install. Check pedal tightness and re-grease pedal threads if necessary.
• Crank Arm Feels Loose/Wobbly:
  • Cause: Crank bolt is loose, or the square taper interface is damaged due to prolonged riding with a loose crank.
  • Solution: Immediately stop riding. Tighten the crank bolt to the correct torque. If the crank arm continues to wobble or feels stripped, the crank arm or bottom bracket spindle may be permanently damaged and require replacement.
• Pedal Unscrews Itself:
  • Cause: Pedal was not tightened sufficiently during installation, or incorrect pedal (left/right) was installed on the wrong side.
  • Solution: Ensure the correct pedal is on the correct side (left pedal is reverse threaded). Re-tighten pedals firmly.

6. Specifications

Detailed specifications for the Varstrom EC38-FO Crank Arms:

An image detailing the product specifications including model, material, crank length, type, color, and compatibility.

An image illustrating the EC38-FO-JIS crank arm, emphasizing its 45-degree rhombus type and 0mm offset, with a close-up of the 15.9mm/0.6inch square hole dimensions.

7. Warranty Information

Varstrom provides the following warranty for the EC38-FO Crank Arms:

• Returns: 30 days return policy from the date of purchase.
• Repair or Replace: 365 days (1 year) repair or replacement warranty for manufacturing defects.

Please retain your proof of purchase for any warranty claims.

8. Customer Support

For further assistance, technical support, or warranty inquiries, please contact your retailer or the Varstrom customer service department. When contacting support, please have your product model (EC38-FO) and purchase details ready.

For general information and resources, you may also refer to the official Varstrom website or consult a certified bicycle mechanic.