The center portion of the lane collects oil. That part of the lane:

Oil drippings from cars collect in a strip in the center of each lane. Unless it is raining, this area still usually offers good enough traction for safe riding.

• Should always be avoided.
• Should be avoided if it is raining.
• Offers the best traction in the lane.
• Will allow you to ride faster than other parts of the lane will.