PriO

I dont think its suppose to be sharp like that.
Is this a sign that it should be replaced? I should probably change my rusty chain too

Retro Grouch 

I can't tell by looking if a cassette needs to be replaced or not. If a new chain doesn't skip on it, I'd keep it.

The shark fin shaped teeth that you have circled are shifting aids. They are designed to help the chain move from cog to cog when it hits that part of the cassette. If that shark fin shape was caused by wear, all of the teeth would be shaped like that.

frozin

how many miles do you have on that drive train?

looks pretty old, but should be fine unless you replace the chain- then you'll definitely need a new cassette too.

supcom

Notice how the odd shaped teeth are all in a line. And the adjacent teeth on the same cogs are shaped normally. If the oddball teeth were worn, the other teeth on the cogs would show similar wear.

Those teeth are obviously designed that way.

sch

Hard to focus those digitals on what you want isn't it? What I can see looks like standard tooth
shaping to facilitate chain pickup when changing gears. Some wizard engineer 15+ yrs ago
figured out that altering the profile on the teeth and with chainwheels adding pins and ramps
makes the bike shift with greater facility. It is now standard on all bikes, at least LBS type
bikes (except fixies of course). This is not wear. It doesn't mean the cassette/chain isn't worn
but the pix doesn't help there. Steve

PriO

Thanks guys.
This is a 1993 bike and im pretty sure the original owner didnt change it since. I just acquired it in July. Im probably going to change the chain first as Retro Grouch stated.

And it actually does skip sometimes, I have to adjust the screw every week or so.
Also, most of the new cassette im seeing doesnt have the shark fin, instead they have holes in them. Are those better if so, should I go with SRAM or Shimano?

Thanks in advance!

seely

Skipping isn't a problem associated with a limit screw really... thats more to do with cable tension. Once you have the limit screws set properly, only once in a million years do you really need to fuss with them again!

F1_Fan

There's a good chance if it's had regular chain replacements that the cogs are OK. I see 8 of 'em so for 1993 that means it's likely either Dura-Ace or Ultegra (wait... was there 8-sp 105 in 1993?). Both quite durable. I'm still running the same Dura-Ace 13-23 cluster on my 1991 Specialized (well I do swap out to a 12-21 for a few months in the summer) and it doesn't skip with new chains.

PriO

Im pretty sure its all 105. The front hub is DuraAce though.