I'm looking to replace the cassette, chain and chainset (just need the chain rings?) on my old mountain bike... all existing products are Shimano IG components which I've found I will struggle to replace.
Therefore I'm looking to use the Shimano HG range (open to other reasonable options) please could someone advise if all HG products i.e. HG30 and HG70 are compatible with each other?
My current cassette is 7 speed 11-28 and my chainset is 24-34-48, should I therefore also stay with this configuration?
you can mix and match shimano and sram all the way up and down their lines.
here's what to what for as far as compatibility:
google "freehub vs freewheel" and find out whick one you have.
ditto "chainring bcd" and find out which ones you have. you just need the chainrings.
chains come in different widths. you can use "8 speed" chains as they are the same width as 7.
the chainrings you shop for may be described as "9 speed" but that is okay they will work fine.
this is your chance to ubgrade to 8 or 9 speed if you so choose. the only extra piece you will need is a rear shifter (not a derailler, they are universal) to go with an 8 speed cogset. or 9speed cogset and chain.
you will need special tools to remove the cogset and crankarm. they are available at any bikeshop.
i highly reccommend getting any bike maintenance book. the smaller the better becasue honestly there's not much to it. there's alot of little tricks tho and having a book that you can pick up and quickly refer to is invaluable.
I think i'd "upgrade" to a 9speed, not because it's actually better, but because you'll more easily find quality replacement items in 9speed than in 7speed. Of course, this is assuming you have a freehub set-up, not a freewheel.
Also, if your shifters are ancient enough, and they run on friction, they'll almost certainly have enough pull to run across a 9speed cassette. If they're indexed, then you'll need a new rear shifter, as dude with the Ryu avatar had mentioned. Shifters are expensive.