What are leadership roles?

Guide rollers: Small rollers that are located in the chain tensioner of the rear derailleur. These guide the chain from the chainrings of the crank cleanly through the rear derailleur back towards the sprocket set.

Leadership roles:
 Small rollers that are located in the chain tensioner of the rear derailleur. These guide the chain from the chainrings of the crank cleanly through the rear derailleur back towards the sprocket set.

Relevant articles:
Adjusting bicycle gears , cleaning bicycle chain