I’ve got a long history of finding slightly obscure technical hitches with bikes……………

so saturday i fitted a new chain and cassette to my road bike – switched from 12 – 27 to 11 – 28 cassette. Chain jumping all over the place on small ring……

Tried every adjustment in the book to no avail.

Whisked down to lbs who quickly diagnosed – needed a different lock ring as 11 tooth was smaller so chain hitting was the original one

now I’d never have thought of that! expect there will be loads on here who had the same thing though

Did the new cassette not come with a new lockring? That strikes me as odd.

It’s a shimano cassette but campag free hub, so the supplied lockring Doesn’t work unfortunately…..

good ole campag…

I ran into that when I was building my 11-36 9-speed cassette, ended up turning down the lockring a bit til it cleared but it was pretty annoying!