Bicycle Headset

It's been a while since I've adjusted headset bearings, but as I recall even high end bicycles the threads are on the fork tubes. The inner race of the top bearing engages these threads, and by tightening or loosening the top and bottom bearing sets are adjusted. The inner race of the lower bearing is pressed on to the fork tube, and the outer race of upper and lower bearings are pressed into the head tube and captured between the fork and the upper inner race.

The only thread-less system I've seen was on a very cheap bike (Walmart/Kmart). The upper race was held in place like a ferule. To adjust: you loosened the ferule moved the race with a hammer to tighten, or pryed it with a screw driver to loosen, then tightened the ferule nut. It took a while, but I was able to get the bearings correctly adjusted on a bike my mom bought for my nephew.

If your "thread-less" system is as I first described, replacement should be easy with parts available at any good bike shop. However; if they are the ferule type, to make it threaded would require replacement of the fork which is probably as expensive as a well made lower end bicycle manufactured by a reputable company.

The new style of headset is thread less, you have a star nut inside the steerer tube, and from which you have a bolt going straight to the stem. This is what you tighten/loosen to adjust headsets. Threaded are old, and now are almost obsolete in new bikes.

Just for your amusement... To me a headset is a small pair of loudspeakers, commonly called earphones, together with a microphone. I thought knackered meant tired - well, in a sense I guess it does...

Do I gather correctly that the headset is the front fork bearings?

"...in America they haven't spoken English for years!"

Yes, the bearings which go round the fork steerer tube, and go through the head tube of the bicycle frame.

Try Bike Nashbar, US online/mailorder discount bike parts. I saw an adaptor there that may work for you. Park Tools, a maker of bike tools, has a good website for how to do this kind of work.

If you have the old style threaded fork and bearing cups on the frame, you can convert it but it's a bit of work. You need a new fork. For a road bike that will carbon. You have to remove the old bearing cups from the frame and press in a threadless headset. Bike shops have a press for this that make the job easier. The other part of the job is to cut the fork steerer tube to the correct height, then installing spacer rings and the stem for the handlebars.

I agree, Park Tool has all you need for info. Also try Sheldon Brown and Leonard Zinn sites. There are a lot of old headset standards.

The Ahead type threadless sets are now very standard and easy to adjust. You may need just new bearings, or the cups could be worn and a new headset required, not really a big expense. Bearings are easy, and you can always place loose balls in place of the retainer types, I get the bearing balls right from McMaster Carr. Do not try to mix and match (unless you are using name brand adapters made specifically for the purpose) or kludge your own headset and stem, stem or fork /tube failures can be catastrophic to the rider.

If in doubt, see (and support) your local bike shop. Find the oldest mechanic in the place, he will be a wealth of info. Cheaper than a trip to the dentist if you mess up your stem assembly