Ritchey logic threadless headset 1 to bring you a solid and reliable component with a low overall weight, ritchey has given its smooth performing logic threadless headset a smaller upper bearing and a larger bottom type. This prevents unnecessary bulk from being added to your bike and ensures its hard wearing. Extensively tested to twice the requirements of european standards, its deep bearing cups sit securely in your road bike's headtube to prevent any flex as your sprinting or attacking a climb. Features material chromoly crmo and plastic steerer tube compatibility 1 threadless type conventional stack height 28.3mm upper bearing size 30mm external, 25.4mm internal lower bearing size 30mm external, 26mm internal upper standard headset information s.h.i.s ec30 25.4  lower s.h.i.s information ec30 26 bearing type retainer ball bearingbuy ritchey components from chain reaction cycles, the world's largest online bike store.