Originally Posted by
berner
So far most responders have indicated where on the bike they have carried a tent. In another look at the issue, imagine it has begun to rain, maybe heavily, toward the end of the day's ride. When you reach the intended campsite you would like to set up the tent as quickly as possible so that you and your stuff remain as dry as possible during the setup. A key to a quick tent setup is to prepare the tent in advance from the previous days setup. If the tent is folded up to an appropriate size for where it is to be carried, then rolled up from front to back with rain fly still in place but with poles removed, then for the current setup, the tent can first be staked at the back end so it can't be carried away by strong winds. At This point the poles are inserted and staking out completed. If you have tried to set up a tent in a downpour, then this procedure will keep everything dry over multiple days of rain.
the vast majority, 95%, of tents sold in North America, have a separate inner body with water proof floor and non water proof upper with mesh, the top section called a "fly" is waterproof. The poles go into the main body and the fly generally lays on top, attached at corners to main body. Great for ventilation in hot muggy weather, but not great for setting up in rain-- hence some folks setting up a light tarp first.
if I've ever set up in pouring rain in 30 yrs bike touring, I don't recall. Generally wait out summer storms, same for take down, as with set up.