In reply to remtherockclimber:
Our club had an 'endurance test' back in '65/66 -- coast to coast & back.
Tynemouth to the Solway & back. It was supposed to be 150 miles with a planned riding time of 10 hours. Due to a calculation / map reading error, the planned turnround point at Burgh by Sands was nowhere in sight of the sea, so we rode an extra 5 miles just so that we could say we'd been to both coasts.
Due to a strengthening westerly wind (thankfully behind us on the way back) we ended up doing 160 lumpy miles in 9 hours riding time (about 11 hours including stops.
A group of around 10 set off, and we only shed one rider on the way out to Carlisle at Greenhead. He happily climbed off and got into our one support vehicle.
To put it in context, we were all active club riders doing anything up to 300 miles per week - a mix of time triallists who competed in races of up to 100 miles, and 3rd cat / junior riders who were regularly picking up places in regional events.
So yes -- 180m in 12 hours riding time for a reasonably fit club rider is achievable, but not easy.