Looking through my clipped magazine articles, I found another that is fun and interesting.
I'm not sure that is really "weird" tech, but it is certainly a bit excessive and dangerous!





The biggest I've seen was a quad or a quint (5 person) tandem by Santana... IIRC. I saw it on RAGBRAI, and it was towing a trailer behind the trail-a-bike attached at the back. Crazy.
edit: I found a photo of it! This was in the year 2000. No trailer or trail-a-bike. Still, I can't imagine the logistics of getting this on the road.




The biggest that I have a (good) photo of is an old quad tandem at the Billy Goat bike shop in the St. Louis, MO area. This is the former A-1 bike shop run by Ray Florian Sr. I think he may have built the quad tandem too.



Steve in Peoria