2-speed front derailleur - three possible positions?
That's the high &quot;trim&quot; position.
Most Shimano front road derailleurs have four positions: low, low trim, high, and high trim.
If your derailleur is properly adjusted, after you shift the front derailleur to the low-gear position, it will have a position somewhat outboard that can be reached by pushing the brake lever somewhere between 1/4 and 1/2 the way to full shift.
And as you've discovered, there's a &quot;high trim&quot; position that can be reached by applying light pressure to the small shift lever to move the derailleur slightly inboard from its &quot;high&quot; big-gear position.
Those two &quot;trim&quot; positions allow cross-chaining capability without the chain rubbing on the front derailleur cage.