Buying used bike with quite a bit of rust, mostly the bolts. Some rust  on the  frame. Is there any way to remove this rust from the bike short of buying new bolts? Thanks.

Rust is cancer.  You need to remove every bit.  For bolts, it's likely easiest just to get new ones.  For the frame, sand every trace of rust off.  It's a good excuse to powdercoat it or paint it with weatherproof paint afterwards...

Rust-converting primers and the like will work for a while, but for the long-term, it's gotta go.

H3PO4
Phosphoric acid

Quote from: AlphaFire X5H3PO4
Phosphoric acid

Also known as the compound in Coke that provides the "Ahhhhh" sensation.  Aluminum foil dipped in Coke works kinda well, however its only on the surface.  When it comes down to getting rid of rust for real, you need to get down and dirty and get out the sand paper and paint.

Quote from: cueball220

Quote from: AlphaFire X5H3PO4
Phosphoric acid

Also known as the compound in Coke that provides the "Ahhhhh" sensation.  Aluminum foil dipped in Coke works kinda well, however its only on the surface.  When it comes down to getting rid of rust for real, you need to get down and dirty and get out the sand paper and paint.

That's why you get the hardcore pure stuff and dip your stuff in there. It also doubles as making a good surface for priming. I think it's called "phosphorizing".