Old Campy Freewheel and Derailleur

[sailorkevin]

With advice and encouragement from this group, I replaced the original 13-20 six speed freewheel on this 40-year old CIOCC with a new 13-28 six speed. A longer (8 speed) chain and some adjustment of the B Screw and the bike shifts flawlessly through the full range and quiet as a mouse. This beautiful classic machine will get a LOT more riding time now.

I'm grateful for your advice and actually rather proud that I did it myself. I'm confident working on modern bikes and I have most of the tools to do so, but classic bike present a different challenge (but also a special kind of satisfaction).

Thanks for your help.

[Spaghetti Legs]

That’s great! I love seeing these beautiful bikes still out on the road.

[Hindmost]

Very nice. You're ready for Eroica.

[NHAero]

Excellent! Lovely bike and great to keep it pleasing to ride.

[Ken Robb]

Originally Posted by dddd

I ran that very derailer with an 8s, 11-28t cassette, and it worked surprisingly well.

So using a 7s freewheel having modern HG-type tooth features can give very good shifting across a 13-28t range which is currently offered by Sunrace.

You will likely need a longer chain, and I believe there may be an adjustment feature at the mounting bolt which will adjust the "B-tension" to accomodate the 28t cog.
You won't have a lot of leeway in terms of chain length with which to alter the chain gap between the pulley and largest cog, but adjusting the axle position in the dropout will possibly allow either some chain length choice or at least some fine-tuning of the chain gap.

Some of the chromed Sunrace freewheels are very good-looking, here's a 13-25t:


And here's a 13-28t made by Giang, axle spaced for only 124mm spacing:

My Nuovo Record derailer shifted a 13-28 Sunrace 7 speed very well.