I have a roadbike with an older Shimano 105 set of brifters. The left hand / front shifter has always had problems getting the chain to the big ring, to the point I often have to dismount to reset the chain.
Recently someone pointed out that my shifter outer was "weird-looking" and I had no idea, because this was all hidden by my stem while riding normally.
The outer lies normally when untensioned but twists like this when I change to the big ring only. Shifting to the middle ring from the grannie works fine.
What has caused this? It used to work acceptably but has never shifted well.