14-26T 6-speed freewheel with Italian thread

[sebinho]

Hello,

If you have a 13 or 14-26-tooth 6-speed freewheel with Italian threading for sale, please let me know. A Regina freewheel would be ideal. Must have 26 teeth on the largest cog.

Thanks,

 

[Cycleops]

Hen's teeth come to mind. There's only one on the EvilBay and that's an eye watering price.

 

[sebinho]

Hen's teeth come to mind. There's only one on the EvilBay and that's an eye watering price.

Yes, indeed. There are Suntour and Shimano 14-26t freewheels there that are affordable. I haven't asked yet what thread these have. If ISO, I think they can be used. There are new Interloc Racing Design (IRD) 13-26t freewheels too with ISO threading. But with import duties to this country, they cost more than I'm willing to pay.

Right now I've got a 5-speed 14-24t freewheel on the bike (the frame/hub fits 6s). I don't live in such a hilly place but an extra 2 teeth would help my knees. My rear derailleur (Campagnolo 980) takes up to 26t apparently.

 

[Ajax Bay]

Suggest you just get on and use a 'normal' freewheel with ISO thread diameter. It'd be, what, 80 microns different.
I also suggest you'd be fine with a 14(or 13)-28. My Nuovo Record RD copes perfectly well with that (6sp).
Paste from Sheldon below [ https://sheldonbrown.com/freewheels.html ]

Freewheel Threading​

The standard ISO threading for freewheels is 1.375 x 24 TPI, the same as for standard ISO bottom brackets.

Type	Imperial	Metric
Italian	1.378" x 24 tpi	35 x 1.058 mm
ISO	1.375" x 24 tpi	34.92 x 1.058 mm
British	1.370" x 24 tpi	34.80 x 1.058 mm
French	1.366" x 25.4 tpi	34.7 x 1 mm
Metric BMX	1.181" x 25.4 tpi	30 x 1 mm

All recent freewheels and threaded hubs, regardless of where made, use ISO threading. The older British and Italian standards use the same thread pitch but a very slightly different thread diameter, and are generally interchangeable.

 

[sebinho]

Suggest you just get on and use a 'normal' freewheel with ISO thread diameter. It'd be, what, 80 microns different.
I also suggest you'd be fine with a 14(or 13)-28. My Nuovo Record RD copes perfectly well with that (6sp).

Thanks. Yes, ISO threading gives a lot more options and 28 teeth would give many more still. I'll see if I can find anyone that has actually tried the Campagnolo 980 RD with a 6-speed X-28T freewheel. Would make life a bit easier as a rider too.

 

[sebinho]

I saw on this old thread:

https://www.cyclechat.net/threads/old-school-campagnolo-friction-rear-dérailleur.169542/post-3392425

You can tell by shifting into the largest cog and see if you can still find X mm of daylight between the top jockey wheel and the largest sprocket when the chain is as tensioned as you are prepared to accept. For every 2mm in X you can have an extra T.

Here are photos of my 980 RD on a 24-tooth cog:





Not sure if I've measured this correctly but there seems to me more than 8mm of space to accommodate an extra 4 teeth.

Does it look like 28T might be a goer to anyone here?

 

[Ajax Bay]

A 28t sprocket is 116mm diameter (tooth tip to tooth tip) (well a 28t chainring is!)
Its radius is about 8mm more than your 24t (btw the plus or minus 2mm in radius per tooth is an accurate rule of thumb* for chainrings too) - relevant for FD height on the seat tube).
Put the chain on small ring / largest sprocket and measure the vertical gap between guide pulley wheel and the sprocket to give you the assurance it'd work.
A 14-28 6sp block is inexpensive and widely available.
I've already told you my Nuovo Record (Pat 76) manages (with a few mm to spare): I suspect the specs (both Campagnolo) are the same.
* Maths: Each tooth needs 12.7mm on the circumference: one extra tooth is ΔC. Δr=ΔC/2π