I replaced the BB on this crankset recently.
I have a spreadsheet here with all Shimano 9/10/11 speed cranksets & BBs
The M523 is the only crankset with these chainrings and bottom bracket. However, the M522 is almost identical with 42/32/24 chainrings & no need to replace BB, and should work with your FD (44t or larger may not work well)
If you change the BB, then there are HT2 options:
MT500-3, M612, M622 are much the same thing, and then M6000 & M7000-10-3 have hollow crank arms ( a bit lighter, but who cares really) are much the same thing but a bit higher spec. M782 is a few grams lighter again, but it's irrelevant really.
Any of these are good, but do check if they come with the BB.
In terms of the chainrings, you have an 'AN' series. The things to note here are:
- The two larger rings are 96mm BCD. This is unique to 40/30/22 chainsets as compared to earlier/trekking designs, which use larger outer rings and are therefore 104mm BCD
- The chainrings are ramped and pinned and the big rings work with specific smaller rings, although I think that as a 96/64mm BCD you might not have any other options here. You won't want to replace 22 with 24, for example.
- I think different AN chainrings should work here (e.g. Deore, SLX, XT), but I'm not promising 100%, you might like to remove yours and inspect them carefully against images online
- It might be more expensive to replace all three chainrings than buy a new chainset.
To replace the crankset you'll need:
- Crank extractor (not necessary if you just want to remove chainrings). Octalink is almost the same as square taper, but it goes in a bit more, so if you have a square taper crank extractor, it won't work and you'll destroy the thread on the crank arms, UNLESS you buy a crank extractor that comes with an extra octalink extension (little metal plug). Cost is about £3 for a cheap Chinese model.
To replace the BB:
- Octalink BB tool, which looks something like a cassette tool but it's not. Again around £3.
- HT2 BB tool, which comes in three sizes, best I can tell this for the weight weenies, but essentially the more money you spend you save 10 grams or something, but anyway, there's a HT2 for everything up to Deore, and then two progressively smaller ones, so if you buy a slightly more expensive BB (which might or might not be better sealed), then you'll need both the Hollowtech II BB tool (which is in the form of a spanner) and an adaptor (TL-FC25). More expensive tools can be purchased.
I had a look on Ebay and both M522 and M523 are around £50 but maybe availability is poor. This likely INCLUDES a BB, depending on where you purchase.
M6000 is certainly more expensive, and you'll need to add a new BB and the tools for that as well. The other HT2 cranksets might be a bit cheaper.
I suggest you inspect the current BB for play and if it's not bad, considering the chainring wear, there doesn't seem to be much benefit in replacing the crankset with a HT2, if it's your chainrings that have worn, not your BB.