It's very important to stay well-hydrated during a long activity. When you are climbing up the hill in the full sun you must have something to refresh your throat. You can have either a water bottle or a bladder to quench your thirst. After our long-distance journeys we decided that the bladder is more comfortable option. Why ? I will try to explain it below in a few points:
- You can drink in every moment of ride, even if you can't let the handlebars go eg. on bumpy road
- You take small sips, not big ones and run of water quickly
- The bite valve of bladder is less liable to get mud from the road so you do not have chew some sand and you also aviod infections<
- A good bladder can be filled with even 2L of water so it last longer and you don't have to stop every now and then for refilling
- A bladder often goes with a backpack which has many useful pockets<
- In the summer cool water feels nice on your back and in the winter your back warms water up
- Packs often have reflector stripes so you are more visible on the road
- If take the bladder out of the pack you have a small pack for wandering around a city
- Put the bladder upside down and you have a shower ;)
A water bottle has some advantages too and I use it during short distance rides. It's easier to fill and I do not have an extra load on my back. However for dawn to dusk trips I recommend taking a bladder.