I have noticed that there are different styles and sizes of headsets and stems, what are they?
Traditional headsets fit threaded fork steerers, Aheadsets fit unthreaded steerers. You can tell which system you have by looking at the handlebar stem. Traditional quill stem for bikes with threaded steerers and headsets Aheadstem for bikes with unthreaded steerers and Aheadsets Traditional quill stem for bikes with threaded steerers and headsets Aheadstem for bikes with unthreaded steerers and Aheadsets When the fork is threaded, the stem’s quill fits inside the steerer. When the fork is unthreaded, the Aheadstem is clamped over the unthreaded steerer. Most better-quality mountain bikes and a growing percentage of road bikes have come Aheadset equipped since the mid 1990s. Note that headsets and stems made for unthreaded steerers are not interchangeable with headsets and stems made for threaded steerers. There are three common sizes. Standard or ‘one inch’ – found on most road bikes and first-generation mountain bikes. Fork steerer diameter: 1″ (25.4mm). Aheadstem clamp internal diam