We’re building bumpers to fit the AM14U. Since it has no mounting points on the cross brace, we made our bumpers like so: http://i.imgur.com/PPX7voA.png
The latches between each bumper slide into one another to support the bumpers in the middle, where there’s no support. The exposed wood at the end of each bumpers would be covered with fabric, but wouldn’t have a pool noodle backing: http://i.imgur.com/ixQKyuE.jpg
Does R21 mandate pool noodle everywhere? Is our current bumper setup legal?
I agree. Not legal. The only thing that can be outside your frame perimeter is bumpers. Bumpers have the cross section in the figure, so what you have there is not a bumper at that point. Effectively you have a ‘hard’ part, that is not recessed a bumper’s width from the adjacent bumpers, which means you use that to your advantage.
For me the first challenge here is hard parts > 1" from frame perimeter (R21B) looking at the combined depth of your wood and latches, although I can’t tell from this whether you’re definitely over.
I’m not seeing anything explicit in the rules on excess wood tangent to and supported by the frame perimeter on non-corner ends within the R21B depth, as the rules focus a lot on the corners, but the cross section problem is probably enough to mean you need a new plan.
Now, if you moved 'em inside and then covered the outside with pool noodles and fabric, you’d have a pretty decent shot at passing–assuming those latches are strong enough to keep the bumpers mounted when paired with the rest of the system.