Can anyone say what reach the SunTour Vx rear dérailleur has.

I have 42/52 in front and (6-speed) 12, 13, 16, 21, 26, 31 on the freewheel.
Now donīt suggest me to try it to know if it might work. I do not have all parts to run a practical test. Otherwise it would be the obvious solution

I also wonder if I can take for granted that a freewheel marked with "REGINA CORSA 2 ITALY 78" has italian threads? Is it made in '78 and therefore the number "78"?

Thanks for any input in these matters.

The Sun Tour literature I've seen seem to indicate that the Vx will run with a 30t, anyway. They don't specify a long cage until 32t. FWIW, I run a V-luxe with a 28t with no troubles.
I also would guess that your Regina freewheel is standard thread. The one that came off my '73 Atala was, as are the three others I have in the freewheel bucket.
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I know of italian-, french-, english- and ISO-threading. Standard thread, is that ISO-threading?
I have an other Regina freewheel, 5-speed, marked with "REGINA CORSA 2 ITALY 79" and it was sold to me as italian threded freewheel on ebay. Should not the freewheel be marked with the kind of threading it has?

Yes, they are marked, but you have to know the codes. Here are the Regina codes:

ISO - 3 grooves on back
English - 1 groove or F.I. stamped on back
French - 2 grooves or F.F. stamped on back
Italian - no grooves or stamping on back

ISO is marginally different than English in diameter (0.005") but completely interchangeable, so consider ISO and English to be standard.

Thanks, very helpful. The one I bought as an italian threaded seems to be just italian since there are no grooves or stamping on the back. The freewheel I was asking about has 1 groove on the back which must indicate english threading.

I've read somewhere that if you use a english threaded freewheel on an italian treaded hub you should not go back to italian threaded freewheel because the threads on the hub gets a little damage and there will be a risk of stripping the threads on the hub if you fit a italian threaded freewheel after the english treaded. Is this just in theory or just if you are a strong rider that apply much force to the threads?

Anders K - I like your avatar.

Sorry - can't help you with your question, but wanted to say that.

Thanks Jon,
Your avatar is nice to

FWIW, I had a Vx on a old Fuji and it had no trouble with a 30 tooth cog.

Thanks,
Better to be on the safe side and run 30 T as the largest sprocket then

I answered that recently in another thread. If you are a strong or heavy rider, it is inadvisable to mix English and Italian threading on hubs and freewheels. There is a 5 degree difference in the thread profile and it MAY cause failures.

It is generally safe to mix the Italian and English threads on hubs and freewheels for cyclists of medium strength and weight, however, once you mixed the threads, you should not switch back and forth.

The above rules of thumb are not just theory. I received a stripped English hub earlier this year, after the owner went back to English freewheel, because he couldn't find an Italian threaded replacement for the one he had worn out.

Thanks T-Mar for your help!
/Anders