Learn how to maintain your headset and you'll save yourself the trouble of trying to find a replacement
The traditional design of headset used to use threaded locknuts that needed huge spanners to adjust; it often came loose, the stems used with it flexed and weighed a ton, and the whole thing was a total faff to work on for home mechanics. Those old threaded headsets were junk, but unless your bike is really old or costs less than £300, then you’ll have a threadless headset (also called an Aheadset) instead. This system revolutionised bicycle steering and we should all be thankful for that.
The biggest headset headache these days is knowing what type fits your bike. Manufacturers have gone crazy over the last decade or so, adding more and more subtly different sizes and designs. However, if you look after your headset you won’t have to worry about finding a replacement for a good while yet.
The most important thing is to eliminate any play. If you find some in your headset then you need to adjust it out ASAP before you ruin the bearings or, worse, the frame.
Adjusting a headset takes about five minutes, but a six-monthly service should also be on your to-do list. The service intervals should be shorter if you’re a fan of river crossings, the jet-wash, or your bike has a cheap headset.