Building your dream headset may not be a goal on every cyclist's list, but we heartily support the endeavor, and so does Cane Creek. Its 110 Series IS5240 Bottom represents one of several separately sold headset pieces that let you choose exactly what will work with your frame and budget, and as its 110 Series, it's the best of the best from a company who only manufactures high end componentry. Part of Cane Creek's integrated headset line, the IS5240 comes compatible with a bottom head tube inner diameter of 52. 1mm. Its dual seal aluminum crown race measures 39. 79mm in diameter and it adds a 1mm to the bottom stack height. Fittingly, Cane Creek includes sealed stainless steel bearings ready to block out grit and water to give you a creak free ride from now until the next century. Yes, we're serious the 110 Series comes complete with a 110 year warranty, so with the proper maintenance, and barring any significant scientific advancements, your headset could very well outlive you.