How To Upgrade Vintage Bike With Sealed Cartridge Bottom Bracket

The crank arms spin on a beefy 24-millimeter spindle permanently fitted into the drive-side arm. Promax hf-2 hollow hot forged 2 piece crank arm set 24mm x 180mm black hollow-forged from 6061-t6 aluminum, both crank arms are hollow so they are super stiff, yet lightweight.