Recently dragged a 1975 Schwinn Continental out of the shed. Tore it down. Re-cabled, regreased, etc. Rides really quiet and smooth now;
On the small sprocket, chain is "skipping" (kachunk noise) when I put any force into my downstroke pedaling. If I pedal very very lightly, it doesn't happen. Problem doesn't show itself when on the bike stand with no load.
I have searched the forums and sheldonbrown, etc. etc, and thought I found the solution 3 times now, haha. Each time to be disappointed on the following test ride. How deflating. I am out of ideas. I am new to bike repair but not a total idiot (well maybe)
Attempt 1 - Since only smallest sprocket acts up (all others work smooth and quiet), I inspected the teeth of the smallest sprocket. All teeth appear to be in good shape, no rounded corners or chips or saw teeth or bent teeth. Maybe there is some other factor I should look for??? I read sheldon on this topic.
Attempt 2 - Checked the horizontal travel, let the H screw all the way out, even released the rear cable pinch bolt completely just to see. no help. Doesn't seem to be trying to shift back to the next sprocket.
Attempt 3 - Replaced old stretched out chain. Measured it and YES, it was a little more than 1/16" longer that 12". Matched new chain to old (and also verified desired length with the equation)
SIMPLE EQUATION: L = 2 (C) + (F/4 + R/4 + 1)
2(17.625) + (52/4 + 28/4 + 1) = ~56"
Maybe the derailleur is bent. Yes it appears to be bent inward toward the wheel. Luckily, I have another old Schwinn in the shed with a GT-500 Schwinn Approved Derailleur similar to the other one. It looks to be in good shape. I clean and lube it. Works well. Install on my bike, test ride, andů..
Also checked the frame by running a string from dropout around headset to other dropout and measuring from left and right side, string to seat post tube. dead center.
The chain does seem a little saggy when on little chain ring and smallest sprocket. I have the wheel pulled into the dropout on the drive side as far as it can go until it hits the hanger which i also checked to make sure it was as far back as it could go. This may have helped a tiny bit.
Maybe I am missing something very BASIC, that will tighten up this problem.
Sorry for the longwinded post, but I wanted to show that I had tried most of the things I have found suggested in forums etc.
Any ideas? A totally different derailleur that will pull up the chain slack, maybe???