Originally Posted by
mountaindave
I like caveman's idea unless you have a cassette lock ring tool, chainwhip and chainbreaker.
I would suggest a 12-32 over 11-32. Nearly uniform spacing in gear ratios. I believe that necessitates a Sunrace cassette rather than Shimano or SRAM, but it'll work fine.
Lastly, I would also go lower on the front large chainring. At least down to a 48. My experience (with one bike) indicates that a smaller gap in tooth count up front helps the RD exceed max tooth count in back. And it can go at least two teeth beyond max.
You likely have a 1056 RD with a 28t max cog, I have nearly the same (same vintage 600 RD with same max) and am running a 30t in the back. I would't be surprised if a 32t would also work. Only a test fit will tell. The thing about starting with a 12-32 and possibly going down to a 12-30 or 11-30 is that your chain only needs to be shortened a bit more to fit.
Good luck!
I with you. I now have learned I can only change the larger Chainring. Mark at Rivendell suggested I do as you and others have suggested. He suggested I go with a 11-28T or a 11-32T with a 46 or 48 T chainring. They stock the 11-28 and 11-32 for $30. They didn't have the chainring but he found one for me on a closeout and Excel sports for $39.95.
Now my only decision is deciding between the options. 46 or 48T and how large on the rear cassette? I'm playing around on Bikecalc.com trying to understand and learn.