RISK 155 Aluminum Alloy Hollow Crank Arm Cap Bolt — M18/M20 × 9mm BB Bottom Bracket Dust Cover for Mountain & Road Bike, 10mm Hex Drive,

The RISK 155 Hollow Crank Arm Cap Bolt is a precision CNC-machined aluminum alloy replacement cap for one-piece hollow crank systems. Designed to secure and dust-proof your bottom bracket spindle, this lightweight cap features a striking clock-face pattern with Roman numerals, a laser-engraved RISK logo, and clear size marking. Available in M18×9mm and M20×9mm specifications, each in 4 anodized colors (Red, Black, Blue, Green). Requires a 10mm internal hex wrench for installation.

Key Advantages

• CNC machined aluminum — precise threads, smooth finish, no tool marks
• Anodized coloring — durable, scratch-resistant, vibrant finish that won’t fade
• Laser-engraved logo & size marking — permanent, clean identification
• Ultra-lightweight — M20 ~8.54g / M18 ~6.85g per piece
• Clock-face design — Roman numeral pattern adds a unique custom look
• 10mm hex drive — compatible with standard internal hex wrenches
• Dust & moisture seal — protects bottom bracket spindle from contaminants

Suitable For

• Mountain bikes and road bikes with one-piece hollow crank systems
• M20 fits Shimano-style cranks (M4000, M590, SLX, XT, XTR and similar)
• M18 fits Prowheel/Howow-style one-piece cranks
• Riders looking to replace worn or damaged stock crank caps
• Bike enthusiasts who want color-coordinated drivetrain components

Notes

• Confirm your size before purchase — measure the threaded hole diameter on your crank arm (M18 or M20). If unsure, use a caliper to measure.
• Torque specification: 5–8 N·m — do not over-tighten
• Requires a 10mm internal hex wrench (not included)
• Package includes 1 crank cap bolt only; crank arm and bottom bracket shown in photos are for demonstration
• Anodized colors may vary slightly from screen to physical product

Product Details