First, mount the bumper on your Basic Robot. A modified version is required to attach it:
The bumper can now be attached to the front of your Basic Robot as shown:
To test the force required for each type of bumper assembly, write a program which slowly increases the forward motor power, 5 or 10% per second, until the switch is triggered, then stops and prints the final value. Apply this program to the trial bumpers in turn and record the power values for each.