Leftside crank arm with diamondshaped hole — direct replacement for bikes that use a diamondshaped crank interface. Check your original crank arm interface shape before ordering to avoid the wrong fit. Key benefits Reliable strength and durability: Solid steel, fully forged construction resists bending and warping for long service life. Restores safe pedaling performance: Replaces a worn or damaged left crank arm to recover stable power transfer and reduce play or noise. Broad compatibility: Designed for cranksets with a diamondshaped interface, making it suitable for many bike types without custom adapters. Fast, loweffort installation: Simple, userfriendly design allows quick replacement at home or on the trail with basic tools. What it does and why it matters Function: Replaces the left crank arm on bicycles that use a diamondshaped crank hole, providing a secure connection between pedal and crank spindle. Problem solved: Fixes bent, cracked, or stripped left crank arms so you can ride safely again without replacing the entire crankset. Performance: Solid steel construction maintains alignment under load and withstands regular riding stresses. Compatibility and applications Interface: Fits diamondshaped crank holes only. Not compatible with square taper, splined, or other nondiamond interfaces. Side: Leftside crank arm only. Confirm you need a left replacement before . Bike types: Suitable for ordinary city bikes, mountain bikes, road bikes, folding bikes, fixedgear bikes, crosscountry bikes, and similar models that use a diamondshaped interface. Practical use scenarios Trail : a bent left crank arm after a crash on a mountain bike to get back on the trail quickly. Commuter maintenance: Swap out a damaged crank arm on a folding or fixedgear commuter bike to restore smooth, reliable daily riding. Weekend tuneup: Upgrade a worn left crank arm on a road or crosscountry bike during routine maintenance to prevent future failures. Notes and reminders Verify the shape of your original crank arm interface (diamondshaped) and that you need a leftside part before ordering. No additional specifications (length, thread, bolts) are included; use the existing hardware or confirm fit with your bike's setup.