Not banging on all cylinders

Not banging on all gears yet with maintenance.

Thought I figured out the problem on the blue bike. Chain seemed to just slide around the middle chain ring when pedal pressure was applied. The teeth on the ring looked very rounded and had a wide valley between them.

Replaced it with an old 42 tooth ring. Not SIS but excellent teeth. Rode in the yard without slipage. Went out on the road and things were fine. After a while, 5 miles, the back began to skip.

Stopped and started a few times to make rear derailleur adjustments for the skip. Help some but the longer I rode the more gears the rear skip developed across.

Went back to the house to see if the problem can be fixed w/o getting new rear gears.

BTW, new front derailleur works well. Need to see if it still works after being raised a mm or 3. When it's on outer ring the inner plate rubs on top of the middle ring's teeth.

Don't want to ignore the rub because I think the teeth are softer than the inner plate. Raising derailleur would eliminate the rub. Then need to find out if shifting is still accurate.

Height is propper clearance for outer plate to outer ring teeth gap. Raising it will raise it out of "gage" height. Need to see if it still shifts as sweet as it does now after being raised. If it still is 'on' will definitely keep it.