R25. Except as allowed per G23, BUMPERS must be located entirely within the BUMPER ZONE, which
is the volume contained between the floor and a virtual horizontal plane 7½ in. (~19 cm) above the
floor in reference to the ROBOT standing normally on a flat floor. BUMPERS do not have to be
parallel to the floor.
So yes, the top of the bumper has to be 7.5" off the floor or less.
Just going off that picture, I would be concerned with a few other rules as well.
R24. ROBOTS are required to use BUMPERS to protect all outside corners of the FRAME PERIMETER.
For adequate protection, at least 6 in. (~16 cm) of BUMPER must be placed on each side of each
outside corner (see Figure 8 2) and must extend to within ¼ in. (~6 mm) of the FRAME
If those front forks are intended to rotate forward in order to pick up the front of the robot, you’ll definitely run into an issue - you need to have bumpers in front of them! Moving the forks towards the center line of the robot would help you get around this - you could have 6" from each outside corner and a gap in the middle that allows the forks to rotate through.
R33. BUMPERS must be supported by the structure/frame of the ROBOT (see Figure 10-8). To be
considered supported, a minimum of ½ in. (~13 mm) at each end of each BUMPER wood segment
must be backed by the FRAME PERIMETER (≤¼ in. gap). “Ends” exclude hard BUMPER parts
which extend past the FRAME PERIMETER permitted by R31-B. Additionally, any gap between the
backing material and the frame:
A. must not be greater than ¼ in. (~6 mm) deep, or
B. not more than 8 in. (~20 cm) wide
While certainly doable, building in supports for your bumper could be difficult with that design. You need support material going across the front/back of the tread and extending into the corner of the robot. You would also need supports extending out inside the tread.
Needing that support across the front/back is also required for R1:
R1. The ROBOT (excluding BUMPERS) must have a FRAME PERIMETER, contained within the
BUMPER ZONE, that is comprised of fixed, non-articulated structural elements of the ROBOT.
So it’s doable, but I would suggest a thorough reading of the rules and planning on how to meet them before you make any purchases or decisions!