Our team has run into a problem with the bumper height using the frame that comes with the kit. Using six inch wheels, the frame is only 2.25 in off the ground. this leaves very little room to for us to mount the bumpers on the frame. Is there a common work around for this?
If you mount the bracket on the center of the bumper, doesn’t that leave a pretty snug fit?
I can understand if you want to have some ground clearance though - in that case, why don’t you just mount the bumper-frame brackets slightly below center? (thus displacing the bumper higher from the ground)
The concern is that according to the rules, the bumpers appear to need to be at least 2" off the ground (http://frc-manual.usfirst.org/viewItem/181#4.1) (r25). That said, our robot is only about 2.75" off the ground as the wheels are 6" in diameter, which puts the fasteners at the bottom most edge of the wood. Is that rule hard set or can we put it just 1" or .5" off the ground? Obviously ground clearance is ideal, but we want to make sure the bumpers dont break off.
Ah, sorry, I missed that (we didn’t start our bumpers yet).
I don’t see the rule changing, so you should start accommodating it.
The best I can think of is to make some kind of metal C-Channel or bar slightly elevated from your C-Channel perimeter that you can mount to the center of the bumper to meet the ground clearance rule.
If your bumpers are 1 inch or half-inch above the ground you will fail inspection.
Put your attachement near the bottom of the bumper so you can satisfy the 2" requirement. Have some vertical supports behind the bumpers that keep it from rotating. These would be permanently mounted to your frame, so you could make them very stable.
Attaching and supporting bumpers can really be thought of as two separate things!
After re-reading the OP’s two posts, I’m confused as to what the question is… 
The bumper rule is unchanged from last year regarding the heights. The short form is that the bumpers must be 5" tall and have a minimum ground clearance ***to the bumpers ***of 2" and a maximum of 5". Since the OP apparently has some part of their frame (a pic or drawing would help) 2.75" off the ground, there is a mounting location for the bumpers within the permitted zone.
Of course, this may alter how the OP wants to attach the bumpers, but everything is about adaptation to opportunities, not dealing with problems :eek: