{"product_id":"black-ops-one-piece-crank-sealed-bottom-bracket-51mm","title":"Black Ops One-Piece Crank Sealed Bottom Bracket – 24 TPI – 51mm – Chrome","description":"\u003cp\u003eThis Black Ops sealed bottom bracket set is designed for bicycles running a one-piece crank (OPC) system. It features a sealed bearing mechanism and chrome-plated steel cups.\u003c\/p\u003e\n\u003cp\u003eThis is for traditional BMX, cruiser, and older steel frame bikes that use American (Ashtabula) style bottom bracket shells. Confirm shell size and crank type before ordering.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eKey Functional Details\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eDesigned for one-piece crank (OPC \/ Ashtabula) systems\u003c\/li\u003e\n\u003cli\u003eThread pitch: 24 TPI\u003c\/li\u003e\n\u003cli\u003eSealed bearing mechanism\u003c\/li\u003e\n\u003cli\u003ePress-fit cup design\u003c\/li\u003e\n\u003cli\u003eCup outer diameter: 51mm\u003c\/li\u003e\n\u003cli\u003eCup material: Chrome-plated steel (CP)\u003c\/li\u003e\n\u003cli\u003eWeight: Approx. 310–315g\u003c\/li\u003e\n\u003cli\u003eSpindle Type: OPC (One-Piece Crank)\u003c\/li\u003e\n\u003cli\u003ePlatform Type: BMX \/ Cruiser \/ Vintage\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eCompatibility \u0026amp; Technical Notes\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eFits frames with American (Ashtabula) bottom bracket shell\u003c\/li\u003e\n\u003cli\u003eShell inner diameter: 51mm required\u003c\/li\u003e\n\u003cli\u003eDesigned for one-piece crank arms only\u003c\/li\u003e\n\u003cli\u003eDoes NOT fit 3-piece crank systems\u003c\/li\u003e\n\u003cli\u003eDoes NOT fit Mid, Spanish, Euro, or PressFit 30 systems\u003c\/li\u003e\n\u003cli\u003eRequires 24 TPI compatible one-piece crank spindle\u003c\/li\u003e\n\u003cli\u003ePress-fit cup installation required\u003c\/li\u003e\n\u003cli\u003ePlatform Type: BMX \/ Cruiser \/ Youth\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eService \/ Ownership Context\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThis bottom bracket presses into the frame’s 51mm American bottom bracket shell. Installation requires proper bottom bracket cup press tools. Sealed mechanism reduces maintenance compared to loose-ball OPC setups.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFit \u0026amp; Use Signals\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eGood Fit:\u003c\/strong\u003e Your bike uses a one-piece crank.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGood Fit:\u003c\/strong\u003e Your bottom bracket shell measures 51mm ID.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGood Fit:\u003c\/strong\u003e You are replacing an older loose-ball American BB.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNot A Fit:\u003c\/strong\u003e Your bike uses a 3-piece crank.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNot A Fit:\u003c\/strong\u003e Your frame uses Mid, Spanish, or Euro bottom bracket.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNot A Fit:\u003c\/strong\u003e You are unsure what bottom bracket standard your frame uses.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cdiv style=\"display: none;\" data-ai=\"mechanic-insight\"\u003eThis is for American BB shells only (51mm). Very common on BMX, cruisers, and big box bikes. Biggest mistake: customer thinks “sealed BB” fits all bikes. It does not. Must be one-piece crank. 24 TPI spindle thread matches most OPC cranks but confirm before ordering. Sealed style is cleaner and longer lasting than loose-ball sets. If frame shell is ovalized or rusted, install will be difficult. Press cups evenly. Don’t hammer them in crooked. Good budget repair option for youth BMX and cruiser bikes.\u003c\/div\u003e","brand":"BLACK OPS","offers":[{"title":"Default Title","offer_id":53103254569274,"sku":"GG-BB-BLKOPS-OPC-51MM-24TPI-CP","price":17.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0745\/5735\/8394\/files\/21462.jpg?v=1772324916","url":"https:\/\/gograva.com\/products\/black-ops-one-piece-crank-sealed-bottom-bracket-51mm","provider":"Grava Adventure Corporation","version":"1.0","type":"link"}