Bicycle Mechanics - Folding rear derailleur?

I have a Specialized sport rock mtb, that whenever I shift onto the small front derailleur and high gear on the cog the rear derailleur folds up onto itself. I replaced the old chain, it was toast. I am thinking that I may not have taken out enough links and that it may be too long. would this allow the the rear derailleur to malfunction in this manner? Also I cant get the front derailleur to shift onto the small chainring. Sometimes I just get lucky and it will go. The adjusting screws have been turned all of the way out and it still stops before allowing the chain onto the small chainring. the cables from the shifters are missing the litttle caps that are usually on the ends and they are frayed. I tried to adjust them from the grip shifter but I am thinking that maybe they are already pulled too tight. But they are also too short to loosen up.o I know that I have to replace the cables for sure, but I would appreciate it if anyone can tell me if or and how I am not adjusting these correctly. Thanx in advance.

King Ajo

Hi King, for starters you should avoid using the small chainring and the high gear on the cog at the same time. It makes the chain run crosswise. It's kind of like shifting a 4x4 truck into Low range and then driving around in 5th gear... they work at cross purposes.

Here are some good instructions on making the chain the proper length: http://www.sheldonbrown.com/derailer-adjustment.html#chain If you end up with a stiff link after doing the shortening, look here for more: http://www.sheldonbrown.com/derailer-adjustment.html#stifflink

Yeah I know not to shift the bike so as to cross the chain, but try explaining that to a friend that doesn't ride much. But anyway thanx for the info.

King Ajo

Is it possible the derailleur pivots and cables are just very dirty or cables old and rusty? If so, clean the ders well and lube the pivot points with light oil. Replace the cables and housings. Everything has to be able to move freely.