Rear Hub Threads.

meagain

Help, I'm confused! (OK, little new there, then.)

Wishing to convert a screw on to fixed, I naively assumed that standard sprockets would fit the hub I intended using: they won't. Mixing and matching bits to hand revealed that the block ("Atom. SICC. Made in Italy") on the hub WILL screw on a Campag - and the fixed sprockets won't. I also have one sprocket (French I think) that won't fit these NOR UK hubs. So that's three threadings?

So, can I source sprockets that fit the Campag and the no-name one (presumably also Italian?). If so, how will the threading be specified?

Any info appreciated! Otherwise I'll have to rebuild the wheel onto a different hub...

meagain

PS Further research (Sheldon naturally!) reveals the differences (tho' not being an engineer I'm not sure of the significance). BUT he concludes "ISO, English and Italian are all semi-interchangeable, but it you shouldn't go back and forth between different types of freewheels on the same hub repeatedly."

Does this mean that I can simply brutally force an English threaded sprocket onto the no-name (I shan't so mistreat the unused Campag Record L/Fs, honest)? Obviously be a b*^"*$r to remove, but a problem delayed is a problem overcome!

Dickie

Hi Dave it is possibly the thread angles as well which differ.

If there is a pitch error it wont matter to much over a short distance. But my feeling is if its pitch error dont force it, this is the worst sort of mismatch.

Use lots of lube I find rocol rtp is best, liquid or semi solid which can be thinned. You are effectively using the sprocket as a die so one turn foward and half back (or till you "feel" it clear) to clear any swarf. You must be clinical when you degrease the hub and sprocket, as swarf gets everywhere and it is not somewhere you need or want lube. If you dont do this you will embed swarf particles into the thread, which will be difficult to clear and further complicte matters. Near pure ali is horrible to machine/work as it is like turning/milling cheese, as this is a forging you should bo ok.

Any problems post it to me and I will see what I can do. If you have a mic or vernier measure the thread od. Hope this makes sense.

1" = 25.4mm (sorry if any of this is teaching you to suck eggs)

Campag/Phil Wood 1.32" x 24 TPI

English/ISO 1.29" x 24 TPI

Old French 33 mm x 1.0 mm

I have edited this 1,000,000 times, english me hmmmm.

meagain

Thanks Rob. Think I'll give it a try and yes, on and off just like a die. Not much at stake really: if it doesn't work then the hub ain't much use to me anyway (unless I continue to run it with its current 5 speed block - which has lots of life in it) so if I knack it, so be it. Also got a near worthless sprocket to use as a die first.

We shall see...