Headsets

[Thorpie]

Being new to this Retro bike game can anyone help me with headset sizes? I know most modern headsets are threadless and usually 1 1/8 in size but how do I find out what size headset/fork steerer I need for my 97 Kona Explosif. It has a threadless A-Headset(Dia Compe) but can someone tell me what I need to measure to confirm what size it is. I sure someone will know anyway but an explanantion would be good for future reference!
Cheers.

 

[Kneedowndean]

It will be 1 1/8"

 

[Hilts]

As a rule 1" headsets dies out around 93 (I think), very few manufacturers used 1 1/4 (Yeti/Alpinestar) so you can normally be safe to say 1 1/8 will be the required size for most bikes post 1993 ..

(prepared to be corrected on any or all of the above)

 

[one-eyed_jim]

As a rule 1" headsets dies out around 93 (I think)

A bit later I'd say. Stumpjumpers were still 1" in '94. Ritchey and Bontrager also used 1" a little later than most. But certainly, things changed pretty quickly from the early nineties when all three standards had a fair showing to the mid nineties where 1 1/8" was the norm, 1" was the exception, and 1 1/4" had effectively vanished.

A '97 Kona is certainly 1 1/8"

 

[one-eyed_jim]

can someone tell me what I need to measure to confirm what size it is. I sure someone will know anyway but an explanantion would be good for future reference!
Cheers.

If you have a bare frame, you can measure the internal diameter of the head tube where the headset cups press in. A 1" headset is 30mm, while a 1 1/8" is 34mm. If the headset is installed and complete, measuring the upper bore gives you the steerer diameter. Measuring the crown race seat tells you it indirectly as the seat diameter is always bigger than the steerer size (obviously) but smaller than the next size steerer up.

Here's a handy table:

http://www.sheldonbrown.com/cribsheet-headsets.html

 

[Thorpie]

Brilliant, thanks.