I have been looking at craigslist for a decent roadbike for my 6 mile commute to school and my friend recommended this Nishiki one to me. Everything looks fine except for rust on the frame that im worried has weakened. Can rust weaken a frame?
https://sacramento.craigslist.org/bik/4068940906.html

Yes rust can and will weaken a steel frame, but there's a fair degree of forgiveness. The key is the depth of the rust, so if you're seriously considering this frame you need to check it out in person. Use the auto mechanics trick of bringing an ice pick to scratch at the rust to find bottom, and/or pushing it through, which is only possible if the rust is nearly through.

One thing to consider on this bike is that the fork doesn't seem to be original to the frame. (not sure, but in that era most forks were painted to match, and replacement forks were full chrome). A replacement fork usually means a crash, so check carefully under the front ends of the down and top tubes cor any sign of buckling, and on top for stress cracks in the paint from stretching.

If your friend is knowledgeable, and advising you already, bring him along (you pick up lunch, or a few beers when you get home) to examine the bike and advise how much more it might need to be brought up to snuff.

Rust never rests.

Neil Young asked me to fix that for you..........

=) OK, it's gravity that never rests?

Thanks for the replies guys. I was hoping I could just sand it down and spray it. Would rather get a bike thats not going to be a project will this one need much fixing?https://sacramento.craigslist.org/bik/4069231449.html

Difficult to say what it might need, because the photos are too small and none are up-close. It looks clean, the frame and fork appears straight, but beyond that, who knows?

That is indeed a replacement fork, and the rusted area (caused by blistered paint) at and behind the top tube lug tells me the bike was in a head on collision. I was going to say the frame was not much affected, but I decided to check. The pic below has a black line next to the head tube that is parallel to the seat tube.

These bikes were generally built with parallel tubes or close to it, so you can see that the head tube is canted more vertical than it probably was originally. That will change the handling somewhat and also reduce the clearance between your toes and the front wheel. I would say you need to ride it and see if it pulls to one side and if the handling and toe clearance is acceptable. Otherwise it's a decent bike, but one other thing can up the cost quickly, and that is the chain. You need to take a ruler and check for wear, then factor in the cost of a chain and freewheel if too worn. Measuring Chain Wear

The Bridgestone is overpriced, as I think that is their low end model. Unfortunately it's getting to be the wrong time of year, but garage sales usually yield better deals than CL.

It can be a problem.