Are all threaded headsets created equal?

The latest thread in my series of n00b questions is about headsets

Are all threaded 1" headsets the same fitment? Apart from the height, I can't see much difference between them. I guess my concern is the diameter of the head tube and the thread on the forks. Diameter for the handlebar stem is set by the inside of the forks isn't it? What usually determines the height of the headset? Is it the nut etc on the top or do they have a habit of stacking up the height between the top of the fork and the bottom of the head tube?

Thanks again for your patience with my l33t n00bity

Not that I know all about this but I'll start.

Apart from the different threads (English, Italian and French) and the stack height the main concern is the cups outside diameter. They must fit the head tube. The other is the crown race inside diameter. It must fit the steerer.

French steerers are also 22.0mm inside diameter instead of the English/Italian 22.2mm so you have to find a proper fitting stem.

Jonny69":30tmp7cx said:

The latest thread in my series of n00b questions is about headsets

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certainly not n00b question . Reading about the 22 and 22.2 is news to me
Learnt some thing new today

And even ones that are supposed to be equal sometimes aren't. I've had 2 Campag Record steel headsets where the frame races on one set were a loose fit in a frame and the other set was tight. They SHOULD be the same - but fork crowns!! I've had to mix and match beteen sets to get a working combination at times. At least 2 different diameters if not more.

It's all a bit of a minefield :twisted:

And don't get me started on stack heights.............................. :roll:

english and italian are identical. French is smaller. However, you can bodge it for french. A bit of sanding down the stem works and the thread pitch is the same, just smaller diameter. Wrap some masking tape round the steerer and then thread on a standard headset and it'll work. Some may scoff, and agreed its a bodge, but it does work.

pigman":1mvzv7gy said:

However, you can bodge it for french. A bit of sanding down the stem works and the thread pitch is the same, just smaller diameter.

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French is 1 thread per milimeter. English is 24 threads per inch. Unfortunately none of my english thread headsets will thread onto my french threaded fork. That fork is really one of kind as it came originally with an english BB threaded frame but has french thread on 22.4 inside diameter steerer! What a mess. LOL

Ok, so what does the stack height do? Looking at my other bikes, technically it could affect the ride height if the height on the bottom part is differrent. Otherwise, it looks like it's just the height of the stack of spacers, adjuster and locknut on the top?

This looks like it shouldn't be too hard to deal with. Just a matter of measuring the head tube and making sure the cups are the right diameter.

Jonny69":1hwoery4 said:

Ok, so what does the stack height do? Looking at my other bikes, technically it could affect the ride height if the height on the bottom part is differrent. Otherwise, it looks like it's just the height of the stack of spacers, adjuster and locknut on the top?

This looks like it shouldn't be too hard to deal with. Just a matter of measuring the head tube and making sure the cups are the right diameter.

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Stack height

Total stack height is the measure to often just under the top lip of the fully assembled top and bottom in the frame. As your frames headtube is fixed, this is just added to the headset stack height. You need to cut your steerer tube to that height. Some headsets may have a variable stack height built in, (notably mavic from bitd (late80/early90) for their mtb, road probably the same and doubtless other road are similar)
Sometimes you can pack the top lock nut upward with spacer in between it and the cup, it depends on the design.

If your steerer is already cut to a lenght, you cannot fit a 'taller' headset as there will be nothing there for the lock nut to screw on to. Look for a different one.

While not going into great details of old headsets (try sheldon brown website ) Sutherland 7th headset section has some nice diagrams
www.sutherlandsbicycle.com/Chapter12.pdf

Ok, I think I understand. Plenty of measurement then, before you start cutting. I think it might be an idea to take one of my other bikes apart to see how it fits together, prior to replacing the other one.