Originally Posted by fietsbob

Die drawn cables wires in cable have been flattened on the outside ,
QBP has those, in stainless steel.
smooth = less friction
You can also get a Teflon coated stainless cables.
less friction too.
same distributor, via your LBS.


It may be picking up Iron oxide from the steel frame,

as it passes under the BB ..

so maybe a Teflon tube thru that guide will help.