When riding for sport or recreation, I've noticed that the amount of stuff I feel that I "need" to bring along is not only subjective, but dictated by my bike's setup. When my bicycle is set up with a handlebar or saddlebag, that bag inevitably ends up filled with things I am convinced I need. What if it rains? Let me just stuff a jacket in there. And a sweater in case I misjudge the temperature. What if I get hungry? Pack some food just in case. Why not stop to take pictures? In goes the DSLR camera. And maybe a book in case I stop for coffee. By the time I am done, the bag is bulging with all the things I "need" for the ride.
And yet when riding a roadbike without any kind of bag attached, I somehow manage to make do with my jersey pockets: Keys, phone, money. Done. Leave. Ride. Even when the morning starts out cold and I end up removing layers of clothing toward the end, I can usually just stuff them in one of the pockets (that's a wool long sleeve tee sticking out of the left one and a pair of gloves in the center). I can keep surprisingly large food items in there as well - riding with a banana or an apple in a jersey pocket has not been a problem.
There is a point of view among cyclists that a bulky saddlebag or handlebar bag on anything shorter than a daylong ride is an affectation and an unnecessary handicap. There is also the opposite point of view - that riding without a fully packed bag is akin to being unprepared and irresponsible. I can sort of relate to both ways of looking at it, depending on the mood I am in. A year ago, I felt "safer" with a bag even if I did not need it, but now I prefer to carry as little as possible. If I want to focus on the cycling, I take only what fits in my jersey pockets. If I am using my bike to explore photographic locations then a bag is a must, but I try my best not to overpack it.
How much do you carry with you on a ride and has this changed with your riding style?