Can you have a U shaped chassis? Rule R101 seems to imply that U-shaped is allowed, but rule R406 seems to indicate you can’t due to bumper restrictions. Nothing explicitly says you can’t.
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Yeah I dont think you can becuase of that bumper rule I think thier just using the same image for every year
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Do you think it would be possible to make bumpers that overlapped and did fully cover the corners? Something like what is shown in the “overlapped padding in corner” picture of R406
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Yes, my team actually does this I can ask my bumper person for some tips if your team would like
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According to R401, “ROBOTS are required to use BUMPERS to protect the entire ROBOT PERIMETER”.
According to R101, “To determine the ROBOT PERIMETER, wrap a piece of string around the outer
most parts of the ROBOT (excluding BUMPERS) at the BUMPER ZONE described
in R405 and pull it taut. The string outlines the ROBOT PERIMETER.
Example: A ROBOT’S chassis is shaped like the letter ‘U’, with a large gap
between chassis elements on the front of the ROBOT. When wrapping a taut
string around this chassis, the string extends across the gap and the resulting
ROBOT PERIMETER is a rectangle with 4 sides.”
Based on this, would the interior part of the U need a bumper, considering it is not part of the (described in R101), ROBOT PERIMETER?
A BUMPER cannot, by definition, be installed inside the U and still be a BUMPER.
Therefore, the Robot Perimeter is not protected. Follow the string for where the Bumper needs to go.
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My reading of the rule R401 sees a <1.25" gap allowed, so if the gap in the frame rail is only 1.25" then you should be fine.
(interestingly there is a typo with the less than or less than or equal to in the figure)
The pipe on the cages is 1 3/8 OD… so it won’t fit anyway
max 1.25in
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Team update 00 addresses this inaccuracy. There are still no bumper cut outs.
You can have frame cut but no bumper cuts other then if it is a multi piece bumper
Note that in previous years there was a rule stating that bumpers must be backed by the frame. See the rule in last year’s manual, for instance:
There is no equivalent rule in the 2025 Game Manual, so it looks like you can just use bumpers to bridge the gap in a U-shaped frame. If you’re worried about whether the bumpers are strong enough, you might be able to reinforce them with material permitted as part of the fastening system rules. There is no bumper weight limit this year, as long as total robot weight including bumpers does not exceed 135 lbs.
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The frame perimeter is always convex regardless of the shape of the robots structure. A U shaped robot would have a rectangular frame perimeter and the bumpers follow the perimeter. If you want a 1” gap in your bumpers and frame I see no reason you can’t.
Yep, the bumper task wanted to eliminate as many prescriptive rules as possible while still ensuring bumpers hit other bumpers etc. This means teams have the ability to make much more or less durable and protective bumpers and robot frames. You could make an X shaped robot frame with a swerve module on each leg, and put corner bumpers with a 1/4” MDF backing on it. This robot would be legal, have a square perimeter, and last about 3 seconds under defense.
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If you made your bumpers with two 1¼" gaps ~6" on center, a CAGE wouldn’t fit completely inside, but plenty enough to reduce lateral motion if you can get it engaged and keep it close to the robot. An obvious issue is that the bottom of a deep CAGE is 3½" from the carpet, and the BUMPER ZONE starts at 2½", so you’d need to pull up on the CAGE a bit over an inch at minimum to make that engagement.
Not this year. The fastening system is one quarter of one rule. (R402D), and is concerned with rigidity of fasteners, designed for vigorous game play, and allowing removable fasteners to be part of either the bumpers or the robot.
The applicable rule this year is two bullets up, emphasis mine:
- B. Backing – A backer at least 4 ½ in. (~115 mm) tall which supports the padding (i.e. padding is not cantilevered other than in corners) and facilitates installation and removal of the BUMPER from the ROBOT (as noted in R410). Additional elements may be added to strengthen the backing, fill space between the BUMPER and ROBOT frame, or serve as part of the attachment system.
So YES, you can reinforce them, but it’s a backing rule, not a fastening rule.
I was referring to the part where it says “reinforce the backing”.
As a member of the bumper working group, I would recommend forgetting previous years’ bumper rules including the idea that there is a standard bumper and you need to find a rule allowing for any deviation from that standard. (I still recommend 3/4” plywood backer though)
You must include all the required parts and follow the overall and hard parts size limits but you can basically build anything in those limits and not worry about whether it’s a fastening system, or if the primary purpose or a piece of metal is clamping fabric or joining a corner.
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