My current set up on my Stanton is 29'er rear wheel with a 30t chainring and 51t cassette
I've just ordered a set of mullet wheels to try, so will be going 27.5 rear (same make of tyre - 2.4 Hutchinson Griffus). I have a spare 46t XTR cassette that I ordered by mistake when I did the build.
So - 29'er 51t vs 27.5 46t. Am I going to have a similar low gear effectively, or at least feel like it?
Same tyre width and same chainring you’re going to have a marginally harder gear on the 27.5 46t cassette vs 29 51t (18” vs 17”)
Search for a gear inch calculator if you’d like to check for yourself
you'll be fine i reckon... not worth any stress over
I would just try it and see how you go. When I went mullet I went up a chainring size but I used the same cassette