Chain length?

2 full links, Shirley? Or is this a trick question?

It depends, as so many of these things do. Given that the chain is a half inch pitch and inner and outer pairs will measure a inch. If you remove two teeth from a chain ring, you've only removed a single link worth of wrap around as the chain typically covers half the chain ring. So for any given length of chain, there are two chain rung sizes that fit. However, what you don't know is if your existing set up was the high, or low end of those two sizes.

Best bet is to resize the chain from scratch rather than trying to calculate. For Shimano 11 speed, that's big/big, full compression and add a pair.

Thanks just checking.  And don't call me Shirley 🙂

Great thanks I'll try that as it seems like a more scientific approach than just removing links.