Dimensions 1 1/8" : 45° x 45°, 30.2 x 41.8 x 8mm
 
Tange Seiki Japan makes the most respected top-notch replacement bearing for headsets in the cycling industry.
Periodic replacement of headset bearings is necessary to eliminate play for smoother, more effective steering. The headset bearing is a vital part of any bicycle, as it helps to precisely and smoothly rotate the bike’s handlebars. If you’re experiencing play (unwanted movement) in your headset, or a rough grinding when you turn the bars, it’s likely that it’s time to service your headset or replace the headset bearings.

You will know if the bike bearings need to be changed, as the steering will feel gritty and the movement will become jerky and stiff. You may also hear a grinding noise when moving the handlebar.

headset bearings on bicycles do need to be replaced from time to time. Below we share a simple guide on how to remove old headset bearings and how replace them.
 
Inner Diameter: 30.2mm
Outer Diameter: 41.8mm
Race Width: 8mm
Degree: 45° x 45°