Choosing the right left crank arm is essential for smooth pedaling and reliable performance across road, mountain, and commuter bikes. This guide reviews five compatible options, focusing on material quality, hole type (diamond or square), length, and installation ease. Whether you’re upgrading to reduce flex or replacing a worn part, the selections below cover common sizes and interfaces for most Shimano-compatible and generic cranksets.
| Product | Crank Arm Length | Hole Type | Material | Compatibility Notes |
|---|---|---|---|---|
| BLLREMIPSUR 2 PCS Bike Wheel Crank Arm | 170mm | Diamond and round hole (left side) | Solid steel | Left crank for square or diamond shaft configurations; includes two left cranks |
| Rhinenet Left 170mm Crank Arm Set | 170mm | Diamond Hole | Aluminium alloy | Left-only crank, lightweight, easy installation |
| Alps2Ocean Universal Left Crank Arm | 152/160/165/170/175mm | Diamond Hole and Square Hole | Forged 6061 Alloy | Multiple sizes, checks hole orientation; city, folding, MTB, and e-bike use |
| WEEROCK Bike Left Crank Arm | 170mm | Diamond Hole | Steel | Left crank replacement for standard 170mm applications |
| THALOUS Universal Left Crank Arm | 170mm | Diamond Hole | Forged aluminum alloy 6061-T6 | MTB, road, e-bike compatibility; ensure right crank matches hole type |
Note: This table summarizes core attributes to help quickly compare five relevant options. Always verify hole orientation and thread compatibility with your specific crankset before purchase.
BLLREMIPSUR Left Crank Arm Pair – 170mm
The BLLREMIPSUR crank arm is a left-side replacement built from solid steel, delivering high strength and durability for mountain and road bikes. It ships as a two-pack with two 170mm center-to-center arms, designed to fit center shafts with a diamond or round access, depending on the original configuration. The product emphasizes robust construction to resist warping and extend service life, making it a practical option for riders needing a reliable replaceable left crank.
Rhinenet Left 170mm Crank Arm Set
Rhinenet offers a lightweight aluminium alloy left crank arm designed for 170mm setups. The listing emphasizes high-strength, high-hardness materials that resist deformation and provide reliable operation. It is advertised as easy to install and use, with a length that prevents overlap with chainring bolts. The product is specifically labeled as a LEFT crank arm, simplifying shopping for replacement parts in mixed crank systems.
Alps2Ocean Universal Left Crank Arm
Alps2Ocean supplies a forged 6061 alloy left crank arm available in multiple lengths, including 152, 160, 165, 170, and 175mm. The model supports both diamond and square hole orientations, making it a versatile choice for various crank configurations. Prospective buyers should confirm hole type and compatibility with their crankset’s spindle interface, ensuring a proper match to avoid installation issues.
WEEROCK Left Crank Arm – 170mm
WEEROCK offers a steel left crank arm at 170mm with a diamond hole interface. The construction emphasizes durability and a straightforward installation process. This option is suitable for riders who prioritize a robust steel component and a standard left-arm replacement that aligns with many older or heavier-duty cranksets.
THALOUS Universal Left Crank Arm
THALOUS presents a forged aluminum alloy 6061-T6 left crank arm at 170mm with a diamond hole interface. The listing highlights high strength, light weight, and durability, suitable for MTB, road, e-bike, and exercise bikes. Before purchasing, confirm that the right crank arm uses a compatible hole orientation, as diamond holes require matching configurations to ensure proper fit and function.
Buying Guide: Key Considerations For Selecting A Left Crank Arm
Choosing the correct left crank arm involves a balance of fit, material, and installation practicality. The following factors help buyers evaluate options based on typical cycling needs and crank configurations.
- Hole orientation: Diamond hole versus square hole. Diamond holes align with certain crank designs and need matching spindles; square holes are more common in legacy systems. Verify both the left and right crank interfaces to prevent mismatches.
- Crank arm length: 152–175mm is typical. Longer arms can provide more leverage but may require adjustments to pedal position and cadence. Choose a length that matches your riding style, leg length, and crankset compatibility.
- Material and durability: Steel arms offer maximum strength and impact resistance but are heavier. Aluminum alloys provide good balance of weight and stiffness, while forged alloys (like 6061-T6) are popular for their durability and corrosion resistance.
- Compatibility: Confirm spindle type, thread pitch, and whether the replacement is left-arm specific. Some products are sold in pairs (two left arms) while others are single items; check what your bike requires.
- Installation ease: Some cranks include simple press-fit or bolt-on installation, while others may require professional alignment to prevent misalignment and chainring interference. Review the product’s installation notes for torque specs and alignment tips.
- Intended use: MTB, road, city, folding, or e-bike designs may dictate different crank arm materials and strengths. If you ride aggressively or in rough terrain, prioritize higher durability and better load distribution.
- Aesthetics and finish: Painted or anodized finishes can improve corrosion resistance and appearance, especially on exposed frames. Consider color and finish matching for a cohesive look with your bike.
Across these options, buyers should focus on the correct hole orientation, arm length, and material to ensure a long-lasting, reliable replacement. The five products covered here represent common choices from steel to forged aluminum, spanning standard and versatile designs suitable for a wide range of bikes.