Need new cassette for commuter: clueless

[BikerKitty v2.0]

:) I think it's time - lots o' chain suck, slipping all over the place when shifting and going up hills, had it tuned up last fall and was told the cassette is worn and probably wouldn't make it much longer, so here we are.

I have a Bianchi Sparta commuter (an '05), which apparently may have come with a really crappy stock Sunrace 8-speed cassette. Let's upgrade, shall we?

Enter the dumb questions:

1) What's the diff between a road cassette and a mtb cassette? To me, it looks like the mtb ones are more squished together, but I know nothing about these. Enlighten me.

2) How's the Shimano XT M737? I'm looking at REI.com 'cause I still haven't spent my dividend check, and this is the only way I can justify buying new bike parts right now.

3) Aside from the chain, what else do I need to replace when I switch this out? Crankset? I wonder if that's worn, too. I'm not sure how to tell. :(

4) Anyone want to "help" while downing a 6-pack in my garage? :)

I guess basically I want something durable but still fairly light.

Thanks, and sorry if I sound ditzy...I'm not (shut up, Dvo1), this stuff is just NOT my forte.

[gordanfreeman]

generally you only need to replace the chain and cassette, the larger chainrings on your cranks wear slower and need to replaced less often. if the front rings are starting to look worn, new rings definitely won't hurt.

[jeffgude]

Looks like you would be wanting 11 -32 8 speed, correct? Unless you are looking for a higher or lower gear range. The M737 might be a little bit more than you need for that bike.

You would probably be just fine with this SRAM cassette for 1/3 the price.

http://www.rei.com/product/698250?vcat=REI_SSHP_CYCLING_TOC

depending on wear, you probaly want to replace the middle ring. I don't see any of those at REI's site, but you could go with something like this, they should have the correct bolt pattern:
http://www.speedgoat.com/product.asp?part=71945&cat=30&brand=199

[bike>>rider]

1) A mtb cassette spans a larger range of gears, typically 11-34 or 11-32, whereas a road cassette will generally be 12-23 or 12-25, or thereabouts. A mtb cassette, thus, looks "larger" as a cluster of gears, while a road cassette in comparison looks tiny -- easy to tell the difference at a quick glance. I'd suggest replacing your current cassette, road or mtb, with the same style. Make sure you get a cassette with the proper # of cogs (e.g., 8 speed or 9 speed -- the number of different cogs on the cassette) based on what you presently have.

The "crankset" may never need to be replace, but eventually the "chainrings" (the gears on the front) will. Look at the teeth to see if they are beginning to look like a shark's fin (angling toward the rear of the bike). If so, you should consider replacing them, but they tend to wear slower than cassette cogs, and frequently can be replaced half as often as a cassette.

In contrast, a chain stretches faster and wears out quicker than either the cassette or chainrings - so definitely replace it, and do so again after about 2000-3000 miles, as a ballpark figure.

[dbruning]

replace with another 8 spd sram. Order online through rei (to support MORC use link in gear) and ship it to the store...or just get one at the store (but commute?!?). I'd say get a 8spd sram chain too!