I have a semi integrated headset (push fit cups inside frame) which is soon in need of replacement. Looking at the options from different manufacturers, I see a huge difference in the depth of the internal cups. Some push in only about 8-10 mm deep some are really long (25mm or so at a guess) can any one tell me the reason why there is a difference and which type I should be getting ? Cheers

probably based on intended use – the deeper cups will be designed for harder hittign frames.

you need to get the one that’s designed for the standard of your headtube, though.

details here;