All the headsets in this category are to fit standard 1 1/8" head tubes. This is a standard mountain bike size but is used on a large percentage of trials bikes across all wheel sizes.
The most basic headsets use standard ball bearings housed in cages, this keeps all the bearings in place if you need to disassemble the headset for any reason. Most of the headsets listed below use cartridge bearings, where the bearings are housed in a steel retainer to keep all the loose balls in place and help shield them from the elements. In more expensive headsets, seals are added to these cartridges to ensure smoother running and better resistance to water and dirt. In all cases the bearings can be serviced and re-greased. All of the headsets we sell are strong enough for trials use, but they generally become lighter and of better quality the more money you spend.
If you need to double check that one of these headsets will fit your frame, the size of the hole in your frame's head tube should be 33.90mm. If your head tube is a different size it's likely that you need an Internal headset, where the headset cups sink inside the frame (rather than being visible externally). The size of head tube for an internal headset is 43.90mm.
TartyBikes Ltd, Units 3-4, Club Street, Bamber Bridge, Preston, PR5 6FN