CANE CREEK 40 ZS49/28. 6 UPPER HEADSETON THE UP AND UPHeadsets can be a tough thing to figure out. Sometimes you'll need a different size headset on the top than you would need for the bottom and sometimes you'll need to replace one but not the other due to wear and tear. The Cane Creek 40 ZS49/28. 6 Upper Headset is the upper portion only (half of a complete headset) for use on bikes that require a non-matching top and bottom cup. This item allows the use of a traditional 1 1/8 steerer tube fork inside a frame with an upper headset built to the ZS49 spec. FEATURESDesigned to fit ZS49/28. 6 upper tubes | Cane Creek | 40 Zs49/28. 6 Upper Headset | Black | 49Mm, Conversion 1-1/8" Threadless