As mentioned in
this thread (and plenty of other places), the new frame perimeter rules helped encourage the use of non-rectangular frames. Sure, we've seen a handful of them before [insert obligatory nonagon comment here], but never in the quantity we saw in 2013 (or some of the irregular shapes). From circles (3574), to hexagons (2851), to v-shaped septagons (1425), to adding irregular pentagons (4334), there was a lot more creativity in frame design this year.
This thread is to discuss the obstacles and advantages presented by these unusal frames. Why did they come to this design? How did teams use them to their advantage? What challenges did they face along the way? How did they solve those challenges? How to did they build their bumpers? Where did they place their wheels, and why? How did it change their approach to maintenance? How did they perform structurally? Etc.