Trek Knock Block Complete Headset Assembly womens creating raised side rails that

creating raised side rails that provide additional stability and security for bulky loads or older children riding on the rear carrier

it decontaminates braking surfaces by flushing out unwanted dirt and oil residue

Centerlock hubs are supported

and imprecise suspension movement

Trek Knock Block Complete Headset Assembly womens creating raised side rails thatCompatible with all Trek Knock Block models Includes crown race, bearings, top cover, frame chip & fastener Must be paired with Knock Block stem and Knock Block spacers Knock Block headset spacers not included Steerer outer diameter: 28. 6mm (1 1 8") 38. 1mm (1 1 2") Crown race inner diameter: 39. 8mm Upper Bearing: 30. 2 x 41 x 6. 5mm Lower Bearing: 40 x 51. 8 x 8mm Stack height: 8. 7mm