This one is a Mustang from Trelleborg. It has
a "Gel" saddle from Bianchi and the
Shimano 5SP Positron shifter with a single
chainring. Perhaps somewhat surprisingly it
has a kickstand and a rack. The tires are
32-630 or 27x1-1/4.

Today I got the shifting to work!

The only challenge was that the adjustment
screw was behind a plate with a hole in it,
only this hole is too small for all my bits
drivers to enter, so an ordinary, thin PH2 made
it happen.

Altho I measured the old chain pin length to
around 8mm, maybe 8.1, I put on a
KMC Z8RB chain which is 1/2x3/32" with
a 7.1mm (9/32") pin length. I suppose it is
intended for 8S casettes but it worked fine for
the Positron FHEM 5S - at least all sprockets
are reachable when the bike is in the stand.

--
underground experts united
http://user.it.uu.se/~embe8573