Alps2Ocean Bike Crank Arms — Forged 6061 Alloy Diamond-Hole 170mm | Lightweight Durable Ebike Replacement

Alps2Ocean Bike Crank Arms are forged 6061-alloy replacement crank arms with a 12mm diamond-hole spindle interface, offered in ten lengths to fit a wide range of ebikes and bicycles.

These crank arms are engineered to deliver reliable strength and a precise fit for mid-motor electric bicycles and conventional bikes that accept a diamond-hole interface. Built from forged 6061 aluminum, they resist deformation while keeping weight low. Choose from ten lengths — from 89 mm for aggressive riding positions to 175 mm for riders who need extra leverage — and install the left and right arms labeled L and R for correct operation.

Which lengths are available and how do I pick the right one?

Alps2Ocean offers ten crank arm lengths: 89, 102, 114, 127, 140, 152, 160, 165, 170, and 175 mm. Shorter arms suit aggressive or high-cadence riding, while longer arms increase leverage and are better for lower-cadence, torque-focused situations. Measure your current crank length or consult a bike fit specialist to match pedaling style and knee comfort.

• Lengths cover compact to long-crank needs (89–175 mm).
• Short arms favor quick cadence and clearance in technical riding.
• Long arms deliver more torque for climbing or heavy loads.
• Confirm measurement from pedal spindle center to crank center.

What is the spindle interface and will it fit my bike?

These crank arms use a diamond-hole spindle interface with a 12 mm hole diameter designed for compatible mid-mounted motors and certain ebike bottom brackets. Verify the diamond-hole orientation and size on your current crank or motor. Using mismatched interfaces will prevent installation, so compare shapes and dimensions before buying.

• Diamond-hole interface: 12 mm diameter.
• Compatible with mid-mounted motors and some ebike setups.
• Check orientation and hole pattern against your existing crank.
• Not universal — confirm compatibility prior to purchase.

How strong and durable are these crank arms?

The arms are forged from 6061 aluminum alloy, a common material for performance drivetrain parts, offering high strength and resistance to bending under normal riding loads. Forging increases material density and fatigue resistance compared with simple casting. While robust for intended ebike and bicycle use, correct installation and periodic inspection increase service life.

• Forged 6061 alloy for enhanced strength and durability.
• High hardness minimizes deformation under load.
• Designed for ebike torque loads when used as specified.
• Routine torque checks and inspections recommended.

How do I install these crank arms and what is included?

Crank arms come as a left/right pair clearly marked L and R; installing them on the correct sides is essential. The package includes two crank arms plus crank bolts. Follow your motor or bike manufacturer torque specs and ensure both sides share the same diamond-hole orientation for proper fit and safety.

• Package: left + right crank arms and crank bolts.
• Parts labeled L (left) and R (right) for correct installation.
• One pair intended for ebikes with compatible mid-mounted motors.
• Use correct torque settings and verify alignment during fitment.

Who is this for: Riders and maintenance technicians who need a strong, lightweight crank arm solution for ebikes or bikes with a diamond-hole spindle interface. These Alps2Ocean arms suit riders who require specific crank lengths for bike fit, cyclists replacing worn or damaged arms, and ebike builders using compatible mid-mounted motors. Ensure the diamond-hole interface and length match your setup before ordering.