Headset Bearing Enduro ACB 4545 405495 SS (40.5×49.5×6.5–45/45) 440C Stainless

ENDURO BEARINGS is an American premium bicycle bearing manufacturer, founded in 1996 in Oakland, California by two old friends — Matt Harvey and Mike Alders. The brand's origin story is a classic garage dream: it started in the attic of a forklift repair shop, with a pile of steel balls, a couple of steel bars, two Apple II computers and a single desk phone as equipment. The idea came from the collision of two men's different careers: Matt had been a bicycle engineer at Gary Fisher Bicycles, White Industries and Bianchi (his signature is on, among other things, the legendary Fisher RS-1 — one of the first seriously credible full-suspension MTBs — and the Bianchi full-suspension road race bike on which Johan Museeuw started Paris–Roubaix), while Mike was working in his father's forklift repair business, hand-crafting forklift mast bearings for older forklifts whose spare parts were no longer being produced. One day Matt realised that exactly the same solution — a full complement bearing, with more balls and no traditional cage — would work brilliantly in smaller bicycle bearings too, where loads are high and rotation speeds are low (for example, on suspension pivots). That insight became the cornerstone of Enduro Bearings. Today Enduro has a roughly 4,600 m² facility at its Oakland headquarters, plus production centres in Gilroy (California), Singapore, Taiwan and a joint venture in China — meaning the company covers the entire spectrum: from economical mass-produced ABEC 3 bearings all the way to its flagship, the XD-15 ceramic hybrid bearings, which are produced from start to finish in California. The XD-15 stands out in its materials: the races are made of nitrogen-infused steel that does not corrode and outlasts even stainless steel thanks to its finer microstructure, while the balls are made of silicon nitride ceramic. The result is a bearing that gets smoother with age, not slower like most ceramic hybrids — and all of that comes with a lifetime warranty. The range also includes, alongside standard bearings, bottom brackets, headset bearings, suspension pivot bearings, fork seals, derailleur pulleys and all the specialist tools required to replace these bearings. Today Enduro bearings are fitted to millions of bikes every year — OEM customers include world-leading brands such as Santa Cruz, Pivot, Rocky Mountain, Trek, Canyon and Cervelo. The philosophy Matt and Mike set out in 1996 still applies today: listen to the problems of mechanics, bike builders and riders — and then build a solution that handles them and lasts longer than anyone expected.