I happened to see this dude called Dan cycle 150 miles in a day (in the video below).
Inspired by that, I set out to do something similarly crazy myself. I wanted to be well prepared gearwise. I had brand new handmade Continental Competition Black Chili tubular tires on my Hed wheels, and a new chain and cassette on my trusty old Cervelo P3. Everything was already ready to go, with the possible exception of me of course. I've done some training indoors on my Tacx Bushido, but not too much on real roads.
The first day I managed to ride 136 km (84.5 miles) before stopping in another town for a night's rest at my relatives' home. The weather was ideal, sunny 21 C (70 F) with a nice cool breeze from the sea. I drank mainly Nuun Kona Cola, and a small bottle of Coca Cola and a can of Red Bull. I wore Orca triathlon shorts, which felt great with just the right amount of compression. No issues whatsoever you know where.
I continued next morning, feeling good. It turned out to be a hotter day around 27C (80 F). My Suplest triathlon cycling shoes as well as my Giro helmet provided excellent ventilation for hot weather.
Nevertheless I perhaps overdosed caffeine (strong coffee for breakfast, 3 bottles of Kona Cola, and caffeinated gels). I started to feel dizzy after 90K. I took Salt Stick caps, but it had no effect on me - too late. I called it a day after 97 km (60.3 miles). Maybe I should have taken more fruit and water like Dan, instead of SiS Go gels and Clif Shot Bloks.
I know 233 km (145 miles) in two days is not that much, but it's by far my longest bike training this year. Overall it was a very pleasant and rewarding experience, except those big trucks zooming by occasionally inches from my body. I installed a red blinking Petzl led light on the back of my saddle. It probably didn't make that much difference, but it helped me feel a little safer.
Anyway I saw lots of cyclists out there, and everyone seemed to be having fun. Maybe not the best day ever, but certainly a couple of great days.