Rear chain skipping regularly

Question
QUESTION: I recently started doing bike trips back and forth from the beach. I am riding a 21 speed Fuji road bike. The back cassette is skipping on the the gear (lowest/smallest) is skipping to the point where I don't even want to use the gear. Whether I am going up a hill or just going straight on a flat surface. This happens on all of the front gears 1, 2, & 3.  My question is it the cassette, chain, or the derailleurs? If is it the cassette the guy at the shop told me to buy all new components and recommended the Shamino 105 set. Don't really know what to do and don't have the money for that either.

ANSWER: Hey sorry it took awhile was away on vacation if I were you I would try changing the chain if it's not that then definitely the rear cog.

IF its still that, try getting a hyperglide chain (the narrower chain)

Let me know if this worked.

George

---------- FOLLOW-UP ----------

QUESTION: Thank you the guys at the bike store were giving me the run around. Bought a new chain and it is still doing it even after they returned the back derailluer. Now the next question I have is, do I have to change out all the components or can I just get a new 8 speed cassette?

Answer
Hey bud,

Ok so the chain is new and its still skipping? The I can almost guarantee 99% that its the rear cog. I had this years ago and its a pain in the a$$ !!

Good news is when you change it your drive train will be spankin new and you will never have to worry about it again....well for a few years anyways.

I'm betting the one you have is old? Oh question? Do you ever stand like out of the seat to peddle hard? Could be that your stretching your chain, in turn grinding the rear cog.

A buddy told me about this and its never happened again since.

Let me know, but I am possitive its that. It CANT be anything else.

George