I use a single set of wheels with a Campy Record chain and cassette. However, I recently got a set of aero wheels that I would like to use once in a while. The problem I find is that with the record cassette being the same age as the chain on the bike now, if I was to use the set of aero wheels with their own new chorus cassette I am guessing I would have difficulties shifting flawlessly due to the cassette and chain wearing at the same rate vs the new unused cassette. Eventually, when this record cassette has gone past its life, I will stick with chorus cassettes, which will last longer.

My questions are:

1. Should I just be putting my record cassette in the aero wheels when I use them or can I use the brand new chorus cassette on the aero wheels without problems? Which way do most people do this with mulriple wheel sets?

2. If I use a 11-23 cassette in my current set up and replace it with a 13-26 or even 13-29, would the same chain I have there now work properly? Would I have to replace the chain for a longer one?

I have a bunch of different cassettes, on different wheels, and for different terrain.

It's not a problem swapping them out, as long as you replace your chain at appropriate intervals.

It only becomes a problem if you allow the chain to stretch, and wear down your cassette. In that circumstance, the old chain and old cassette may run ok, but a new cassette won't with the old chain.

But if your chain is stretched that much, you need to get rid of the chain, or you'll just be destroying your new cassette.

As for the chain length, size it to fit the largest cog. The RD should have enough chain wrapping capacity to deal with the smaller cassette.

Well, how often should the chain be changed then? I swapped frames about 2 months ago. The new record cassette and chain that was in the previous bike had 2500 miles or so. When they attempted to put the new chain with the old cassette, it would skip on the 2-3 gears I used most often, which happened to be some of the Ti cogs. The ran flawlessly on the other bike though. At how many miles should I be changing chains then? I rather change a $40 chain too often than have to replace the $200 cassette too soon!

Depends on how you ride, the conditions you ride in, and how well you clean and lube it. When the chain has "stretched" 1/16" in 12 links, it's time for a new chain.

I would check it after 1,000 miles.

https://www.sheldonbrown.com/chains.html

I replace my chains when the shifting gets noticeably worse. It's usually on one or two cogs. This is long before the chain starts skipping... that's really worn. On a Park chain checker, that's between .75 and 1.0 (on Shimano chains). I get 2000-2500 miles from a 10sp shimano chain. 9sp ones lasted a bit longer. Thats pretty often but my shifting is always good and the cassettes and chainrings last a long time.