Hi guys

I have a 5 year old 29" MTB I use for commuting, and the time has come to replace some consumables - chain/chainset/cassette. I've been trying to sort through & figure out what will be a decent replacement/upgrade, but I can't figure out what is compatible with what.

e.g. can I just swap in any chainset ? A friend has a used Shimano M622 Chainset that he has offered me, but we both haven't done this before - so can't figure out if it will fit !
Never having done this before... I want to replace/upgrade for minimal cost. This is a bike I use for a commuter, so I don't mind if a bit heavier etc, nothing too fancy needed.

I'm just at a loss as to what combination of features needs replacing when you replace another part... e.g. I want to avoid replacing shifters / derailleurs etc if I don't have to... the main thing is to replace the chainset / chain & cassette, all of which are pretty worn down.

Do I need everything to 'match' or what kind of combination should I look for ?

Will e.g. that Shimano M622 Chainset just fit in, or would I need to replace the lot?

Very lost !

OK,
easy stuff first.

You need a Sram, Shimano, or Shimano compatible 8s cassette of the same size (unless you want to change gearing while you're at it)
Any 8s chain, with KMC being popular and reasonably priced.

The crankset is trickier, because it has to be compatible with the bottom bracket, and if you replace that too, with the frame. OTOH, you can simply replace the chainrings as long as the bolt pattern matches.

BUT

Before spending money that you may net need to, find out what NEEDS replacement, if anything. As a general rule, badly worn chains usually call for the cassette to be replaced at the same time, but it's rare that crankset also need replacing.

Thanks, appreciate this super quick reply & this has already helped my understanding a lot.

Re: Cassette/chain - that's great, will look for those. Happy with gearing & I assume not changing it will be cheaper!

Re: Crankset - unfortunately it has to be replaced (the middle chainring, in particular, is very worn down). The SRAM S-200 crankset is a cheap one that is welded together, so I can't replace just a chainring, have to replace the entire crankset... so this is where I have been struggling to find something compatible as I just can't put all the components together and figure out what will/won't fit properly.

What symptom are you trying to cure?

Unpleasant noises initially, but now chain is slipping off a couple of times in each ride. The limit screws are all setup properly, but I think the chain is loose and it is slipping from the worn cassette and chairing.

I normally don't mind, but it has become a safety issue for me commuting & have had to change riding style. (I usually gun it on the bigger rings, but I have to shift down earlier when coming to a potential stop otherwise risk chain coming off if I put too much force through).

Sorry if I have the terminology wrong, I normally just ride and don't really think about it... first time I have to !

the m622 crankset with not fit a square taper BB you'll need hollowtech 2 (if i remember correctly) for that crankset

Yes I think that's correct those BB's are cheap (a lot cheaper than a new crank) and simple to install if you go that route you will probably have to reposition the fd depending the big rings gear count but still your cheapest option (assuming your mates not charging you for said crank)

Ahh yes, replacing a BB is well beyond my expertise !! The M622 is offered for free, but no point taking him up on it if it will be a hassle / costly for me (sounds as if I will need to get a new BB to fit it + get it installed + may have issues with the 10 speed?).

In the meantime, I've been trying to find cranksets with a square taper BB and designed for 8 speed, but there doesn't seem to be many options.

The closest seems to be the SRAM S600 (which looks to be an update of the S200, which I was happy with). If I can pick this up on the cheap, it may be cheaper & easier to swap this out...

There looks to be some older Shimano cranksets too, but I'm not sure if I have to swap out anything else if I go with a different brand. Assuming I can match the gearing/speed ratios, would I need to change anything else - shifters, derailleurs, etc?

There will be be little if any difference in chain ring spacing and if you can pull a crank off replacing a BB is just as easy providing you have the tool and it hasn't welded it self in. A different tool is required for hollow tec install (maybe your friend has one)