I have two wheelsets. One with a 11-28T and the second with 11-34T cassette. I am currently using the 11-28T and was wondering if I need to shorten the chain when using this cassette. It works fine but was wondering if it would shift better or if there is something detrimental that I should be aware of by using the longer chain?

Probably not, the RD cage wrap up should cope with it ..

But, buy a 2nd chain, and make that as you think you need, and see..
probably should anyhow , keep it with the cassette / wheel you wore it in with..
rather than shorten a used chain, to use with a different cassette..






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It's easy enough to mount both wheels and try it out. You said "it works fine" so it sounds like you may have already tried. If so, don't waste time worrying about it any further.

I have that situation, & works fine but the chain is a bit slack in the small/small which I never use anyway.

That combination is the same for both cassettes so if it works for one, it will work for the other.

If you swap cassettes/wheels back & forth, leave the chain sized for the largest cog just for the convenience.
You didn't mention what RDER you have. IF a mountain type, you should have plenty of chain wrap capacity.

The 11-34 cassette probably includes a 28-tooth cog, right? What you are doing seems perfectly fine to me. I used to be all about running my chains as short as possible, but these days I sometimes leave in extra links in case I want to increase chainring size.

Absolutely no need to shorten the chain. That's what the longer cage RD is for. Shifting won't improve and you'll have a chain too short for the 11-34.

Never Fix A Running Piece

Okay, seems there is no harm running the longer chain all the time. I do have a medium cage derailler to pick up the slack so no worries there. Cool...

Are Campagnolo currently recommending their chains be installed on the longer side for smoother shifting?