Originally Posted by
FBinNY
If I'm reading you right, there's never a minimum size cassette, beyond what's needed to not duplicate sizes. By example a 12s cassette starting at 11t would need to top out at 22t.
Other than that, using cassettes smaller than the max size isn't different than not using the larger sprockets on any cassette, which is obviously OK.
Of course, going with a smaller cassette may create other options, like shortening the chain, or using a different RD, but those are only options, not requirements
That is what I thought, but the shimano spec says the min sprocket size is 42t. I see others seem to post that it will only work with a 42t or anomalies will occur.
https://bike.shimano.com/en-EU/produ...M5120-SGS.html