I am working on my son's 90's Trek 930. He asked me to adjust the derailleurs but I think there are deeper problems. There are 3 or 4 "ripped" looking places on the middle gear of his crankset as pictured above. His chain is also showing excessive wear. I ordered a chain but then read a decal stating to use "IG chain only".
1) I assume he will need to get a new crankset. It is labeled Shimano MC34 and is 175mm. I am striking out searching by this number. What would be a budget to midline equivalent for this?
2) Do the "IG" chains read any differently on a regular chain stretch gauge?
3) What causes these "ripped" looking places on the gear? It seems like it would take an amount of violence to tear the metal like this.
4) If I replace the crankset and chain, I assume I should go ahead and replace the rear cassette, What would be a good budget to midline choice here?
5) Do I really need the Shimano IG chain, and if I replace the cassette and crankset both, will I end up with a different incompatibly with the chain
As always, Thank!