TP_Mantis

I have a Record 10 speed cassette (11-23) and i am looking to make it a 12-25 or 12-27. Is there a place i can buy the cogs i need or do i have to buy a whole new cassette?
Any issues adding a cog to the end?
Any issues removing my 11?

timeedgevxr

I had an 11-23 and I bought a cheap Miche 12-27 cassette off of Jenson or Pricepoint last year to make a mutt cassette for hills and fast descents. I built an 11-27 between the two and it worked great. I see individual Campy cogs on ebay all the time. In fact, lots of the online big-box stores sell cogs seperately.

My 11-27 has 5,000 miles on it and still running great. I broke the teeth of a couple this spring, but I had spares of the same sizes from my leftover cogs.

DaveSSS 

What has been suggested will not work with a Record cassette, having two pairs of cogs that are riveted to carriers.

It is just not practical to make the change that you want. Campy individual cogs are expensive and the are radially timed to work best in the factory produced combinations. You will also need a new 12-13T lockring, if all you have is the 11T version.

With Record 10 cassettes no longer made, you would have to look for new old stock Record or Chorus or buy 2009 Centaur. I would not waste the money on a Record cassette since the Ti cogs will last about half as long as steel, in addition to costing a lot more.

The new Centaur 10 cassettes can be had for about $50 from Ribble.

gregf83 

Here is a table showing the cogs on standard record cassettes. As you can see to go from 11-23 to 12-25 you would need to buy one single cog, 12A-1, and three dual cog pairs. Simpler just to buy a new cassette and sell the old one.