I have a 2002/3 Specialized Expedition Sport that came with Shimano Alivio gears front and rear. It has 8 gears on the rear and 3 on the front. I have hardly ever used the front set at all (only really to go down steep hills at speed), so I only really use only the middle sprocket and it is in pretty good condition. I understand that there is little to choose between basic front dérailleur units so I don't think I have to change it.
The rear is a different story. While the rear dérailleur unit looks straight and seems undamaged, the gears themselves are hooked, worn and some of the tips have broken although it all still works ok. So I'm looking to replace the gear cluster (cassette?), the chain and maybe the rear dérailleur unit too. The shifters are thumb push type but I can't work out which ones they are. Specialized seem to use a few different ones on the same model bikes!
Anyway, I understand that the Alivio is a low end product and it might be best to go up the range to maybe "Deore" or "Deore XT" (?), but then I hear things like long cage and short cage and the huge list of different models and gear ratios available.
So 1). What is a good replacement for the Alivio?
2). What do I need to buy (jargon time lol)?
I use the bike for general commuting, getting about town and sometimes some "green" miles along country lanes and fields and I am on a lower budget rather than a big one!