I had that kind of frame for a mountain bike back in 1997. Almost the same design with Ritchey stamp name at the drop outs and hub mounts. Except the cable mounts are located at the side of the top tube.
I bought mine with only a thin primer paint and had it custom painted in white.
The bike store where I bought it told me that it was a Ritchey frame and I ...
Open end of a combination wrench should work on the square nut. An adjustable wrench should also work but you'd have to be careful to not round off the nut.
You cannot properly grease the bearings with the pedal assembled. You will not be able to spray grease or lubrication into the bearings.
We know it worked once, but we don't know what was changed, so it's time to go back to basics.
The rear derailleur has a spring that wants to move the chain to the smallest cog.
The shift lever should have enough friction to keep the derailleur spring from going where it wants but not be so tight that it won't move.
The first thing to check is ...
Sounds like the cable is pulling through the binder bolt on the derailleur, so that the shifter cannot pull the derailleur inboard onto the largest sprocket.
The shifter cable needs replacing. Check that the housing is properly located in all the frame stops. It would be good to put a ferrule on the end of the shift cable also.
It's possible that the ...
I'd call it an 80s step-through frame, intended for a woman (denoted by the skirt guard on the rear wheel)
Three black cables show there are two brakes, and probably a 3 speed internal gear hub in the rear wheel.
Observation - there's a lot of seatpost and an awful lot of stem out of the bike - guessing this is a small frame and the current rider is quite ...
It's a Shimano Positron shift cable.
The outer housing is also special.
Picture from WorthPoint.com
I found a few for sale on ebay - not an endorsement.
There were two Positron systems. The first one was very complicated. The since there was no return spring the rear derailleur had two cables to pull back and forth. The later version had one solid wire ...