Bumper Rules

If you keep the minimum 6 inches of bumper on each side, are you allowed to leave parts of your frame exposed, even if you do not have an opening in your robot frame?

yes

Keep in mind that the 6" is measured from the corner of the frame, not the corner of the bumper. So the bumper will really be a minimum of about 9" long from the corner, depending on your bumper construction.

Check out the diagram on page 69 of the Robot Construction Rules book and note that R24 explains that bumpers are required to protect the corners of the frame perimeter. If I understand your question correctly, then the answer is “yes”, you are allowed to leave parts of your frame exposed. But I suggest you read the entire bumper section in detail as there are a number of rules related to the design and construction of bumpers.

Jason